Skip to main content

Medicinal plant Miconia albicans synergizes with ampicillin and ciprofloxacin against multi-drug resistant Acinetobacter baumannii and Staphylococcus aureus



Given the rising occurrence of antibiotic resistance due to the existence and ongoing development of resistant bacteria and phenotypes, the identification of new treatments and sources of antimicrobial agents is of utmost urgency. An important strategy for tackling bacterial resistance involves the utilization of drug combinations, and natural products derived from plants hold significant potential as a rich source of bioactive compounds that can act as effective adjuvants. This study, therefore, aimed to assess the antibacterial potential and the chemical composition of Miconia albicans, a Brazilian medicinal plant used to treat various diseases.


Ethanolic extracts from leaves and stems of M. albicans were obtained and subsequently partitioned to give the corresponding hexane, chloroform, ethyl acetate, and hydromethanolic phases. All extracts and phases had their chemical constitution investigated by HPLC–DAD-MS/MS and GC–MS and were assessed for their antibiofilm and antimicrobial efficacy against Staphylococcus aureus. Furthermore, their individual effects and synergistic potential in combination with antibiotics were examined against clinical strains of both S. aureus and Acinetobacter baumannii. In addition, 10 isolated compounds were obtained from the leaves phases and used for confirmation of the chemical profiles and for antibacterial assays.


Based on the chemical profile analysis, 32 compounds were successfully or tentatively identified, including gallic and ellagic acid derivatives, flavonol glycosides, triterpenes and pheophorbides. Extracts and phases obtained from the medicinal plant M. albicans demonstrated synergistic effects when combined with the commercial antibiotics ampicillin and ciprofloxacin, against multi-drug resistant bacteria S. aureus and A. baumannii, restoring their antibacterial efficacy. Extracts and phases also exhibited antibiofilm property against S. aureus. Three key compounds commonly found in the samples, namely gallic acid, quercitrin, and corosolic acid, did not exhibit significant antibacterial activity when assessed individually or in combination with antibiotics against clinical bacterial strains.


Our findings reveal that M. albicans exhibits remarkable adjuvant potential for enhancing the effectiveness of antimicrobial drugs against resistant bacteria.

Peer Review reports


Antimicrobial resistance represents a major global public health concern, characterized by the emergence of new traits that lead to the loss of effectiveness of a drug, whether they arise naturally or are acquired [1]. Pathogens previously susceptible to several drugs have increasingly shown resistance profiles, due to the extensive use of antibiotics. As a result, these microorganisms have developed several defense mechanisms against the effectiveness of drugs [2], causing c. 5 million deaths annually, which are directly associated to untreatable resistant infections [1, 3]. Therefore, new treatments are urgently needed to deal with multi-drug resistant bacteria (MDR), and, in this scenario, plants can provide a valuable source of bioactive molecules.

Phytochemicals, or plant natural products, are compounds produced by plants that perform several functions, including protection and adaptation of the species to the environment. These molecules have a wide structural diversity and are produced aiming at biological targets, being, therefore, excellent candidates in the search for bioactive compounds, including new antimicrobial agents [4]. Natural products have demonstrated different mechanisms of antimicrobial action, such as promoting cell wall rupture and lysis, inhibiting biofilm formation, preventing cell wall construction, interrupting microbial DNA replication, and inhibiting the synthesis of bacterial toxins to the host, among others [5, 6]. Furthermore, the remarkable activity of phytochemicals against bacterial virulence factors reinforces the potential of plant natural products in the development of complementary treatments for infectious diseases [7]. The combination of natural products with antibiotics has been recognized as an important strategy to enhance the therapeutic effects of drugs and to limit microbial resistance, mainly by re-sensitizing MDR bacteria to antibiotics, besides preventing the spread of antibiotic resistance [8, 9].

Due to the coexistence of plants and microorganisms, most of these phytochemicals exhibits weak antibiotic activity when evaluated individually, and their potency is several orders of magnitude lower than that of common antibiotics produced by bacteria and fungi. However, plants produce a wide variety of compounds and show successful defense mechanisms, generally employing synergism between two or more molecules as a mechanism to combat pathogens and infections [10].

A synergistic effect occurs when two or more chemical compounds are combined to treat a pathology and, as a result, the combined biological activity of these compounds is greater than the sum of their individual biological activities [11, 12]. The use of natural products in synergistic combinations usually occurs through multi-target actions, mostly by inhibiting or suppressing antibiotic resistance, which frequently leads to the utilization of concentrations below the minimum inhibitory concentration (MIC) [13, 14].

Miconia albicans (Sw.) Steud. (Melastomataceae), a shrub distributed in the Brazilian Cerrado and popularly known as 'canela-de-velho', is widely used in folk medicine for treatment of intestinal diseases, infections, arthritis, arthrosis and various inflammations [15]. Antioxidant [16, 17], anxiolytic- and anticonvulsant-like effects [18], antidiabetic [19], antimutagenic [20], anti-hyperalgesic and anti-inflammatory [15] activities have also been reported for this species [21]. Despite possessing several notable biological properties, which justifies its popular use, M. albicans has been poorly investigated for its antimicrobial potential.

In this work, the extracts and phases obtained from the leaves and stems of the Brazilian medicinal plant M. albicans were evaluated for their antimicrobial potential targeting two strains of the most significant and currently encountered clinical MDR bacteria, namely, Acinetobacter baumannii and MRSA, including their individual effects as well as their combined efficacy with antibiotics. Additionally, they were assessed for their ability to inhibit biofilm formation by S. aureus. Chemical profiles of the bioactive extracts and phases, analyzed by GC-MS and LC–MS, were also investigated.

Materials and methods

General experimental procedures

1H and 13C NMR spectra were obtained in CDCl3 or CD3OD (Cambridge Isotope Laboratories) on a Bruker DPX-300 spectrometer (Bruker) operating at 300.13 MHz (1H)/75.47 MHz (13C). Column chromatography procedures were performed on silica gel 60 (70 − 230 mesh, Merck, Germany) and Sephadex LH-20 (Sigma-Aldrich, USA). Gallic acid was purchased from Sigma Aldrich (Sigma-Aldrich, USA). HPLC with diode-array detection and tandem mass spectrometry (HPLC–DAD-MS/MS) was performed using an LC-DAD-HRESIMS system equipped with a SIL-20A autosampler, a DGU-20A3r vacuum degasser, a thermostated CTO-20A column compartment, and an LC-20AD pump, coupled to an SPD-M20A DAD (all Shimadzu, Japan) and a micrOTOF Q-III high-resolution time-of-flight mass spectrometer (Bruker Daltonics, USA) with an electrospray ionization (ESI) ion source, operating in positive and negative ion modes (120 − 1200 Da and collision energy 45 − 65 V). GC–MS analysis was performed using a Shimadzu GC–MS QP-2010 PLUS Gas Chromatograph (Shimadzu Corporation, Japan) coupled to a mass spectrometer operating at 70 eV, equipped with an autosampler AOC-20i (Shimadzu).

Plant material

Leaves and stems of Miconia albicans (Sw.) Steud were collected from Cerrado region, (Município de Rochedo, MS, Brasil; coordinates: 19°52′32.9" S e 54°48′31.7"W), in February 2019. License for research on Brazil’s biodiversity #A5B7329, issued by National System for the Management of Genetic Heritage and Associated Traditional Knowledge (SISGEN/Brazil). The plant was identified by Professor Dr. Geraldo Alves Damasceno Junior (Institute of Biosciences, Universidade Federal de Mato Grosso do Sul), and a voucher specimen (no CGMS 74186) was deposited at the CGMS Herbarium of the Universidade Federal de Mato Grosso do Sul.

Extraction and isolation

Air-dried and powdered leaves (1.6 kg) and stems (1.1 kg) of M. albicans were extracted at room temperature with EtOH, yielding 82 g of leaves ethanol extract (LEE) and 19 g of stems ethanol extract (SEE). After concentration in vacuo, the residues obtained from the EtOH extracts were partitioned between MeOH–H2O 9:1 and hexane, and between MeOH–H2O 1:1 and CHCl3, followed by ethyl acetate, to give the corresponding leaves (L) and stem (S) phases: hexane (LHxP 8.3 g and SHxP 3.1 g), chloroform (LCP 4.9 g and SCP 0.7 g), ethyl acetate (LEP 12.9 g and SEP 9.1 g), and hydromethanolic (LHP 20.3 g and SHP 1.8 g) phases.

Additional chromatographic separations were performed on LCP and LEP to provide reference compounds for the chemical profile analysis. An aliquot of LCP phase (2.6 g) was chromatographed on a silica gel 70–230 mesh column, using step gradient elution with hexane, hexane–EtOAc (1:1), and EtOAc to give 5 fractions (A → E). Fraction C (hexane–EtOAc 1:1, 16.0 mg) yielded compounds 29 and 31 as a mixture. The LEP phase was chromatographed on a silica gel 70–230 mesh column, using hexane, hexane–EtOAc (3:1, 1:1, 1:3), EtOAc, and EtOAc–MeOH (9:1, 3:1, 1:1) as eluents, to furnish 13 fractions (A → M). Fraction A and B (hexane 100%) yield a mixture of 23 and 25, and compound 28, respectively, the latter was also obtained as a white solid precipitate from SHxP. Fraction E (hexane–EtOAc 8:2) gave 18 (63.0 mg), fraction G (hexane–EtOAc 1:3) yielded 19 (3.0 mg), while fractions I and J afforded 20 (30.0 mg) and 21 (40.0 mg), respectively. Fraction H was chromatographed on a Sephadex LH-20 column in MeOH to furnish 9 subfractions (I-IX). Subfraction V gave 10 (10.0 mg).

Chemical profiles of extracts and phases of Miconia albicans

HPLC–MS/MS analysis

Aliquots of the extracts and phases of M. albicans (10 mg each) were separately dissolved in 10 mL of MeOH − H2O (1:1) and filtered through 0.22 μm PVDF membranes (Allcrom, Brazil). Subsequently, 10 μL aliquots of each solution were separately injected into a Luna RP-18 column [5.0 µm; 150 × 2.0 mm; Phenomenex™ Luna PFP (2), USA] coupled to a sub-2 Security Guard Ultra Cartridge for C18 HPLC and a core − shell column (2.1 mm, Phenomenex, USA). Column temperature was maintained at 50 °C, and the mobile phase, at a flow of 0.2 mL/min, consisted of a linear gradient of water (solvent A) and methanol (solvent B), both containing 0.1% (v/v) of formic acid, as follows: 3% B (0 − 2 min), 3 − 25% B (2 − 25 min), 25 − 80% B (25 − 40 min), 80% B (40 − 43 min), followed by washing and reconditioning of the column (80% B → 3% B, 8 min). The DAD acquisitions were performed in the range of 240 − 800 nm. The data obtained were subsequently processed and analyzed using the DataAnalysis® software version 4.2 (Bruker).

GC–MS analysis

Hexane phases (leaves and stems) and the isolated compounds (23, 25, 27–29 and 31) were dissolved in dichloromethane (1 mg/mL), and injected in a Rtx™-5MS Restek fused silica capillary column (5%-diphenyl–95%- dimethylpolysiloxane, Restek, USA) of 30 m × 0.25 mm i.d., 0.25 µm film thickness. An injection volume of 1 μL was employed, with a split ratio of 1:50. Injector temperature was 250 °C, with the carrier gas (Helium 99.999% purity) at a flow rate of 1 mL/min, and pressure of 87.1 kPa. The oven temperature was programmed from 50 °C (isothermal for 1.5 min), with an increase of 3 °C/min, to 260 °C, ending with a 5 min isothermal at 260 °C. The data were processed in a GCMS Postrun Analysis Software (Shimadzu Corporation, Kyoto, Japan). Triterpenes and sterols were identified by comparing the relative retention (RR) of the samples with the RR of the standard compounds.

Antimicrobial susceptibility assays

All reagents and media for the antibacterial assays were purchased from Sigma Aldrich™. The reference bacterial strains Staphylococcus aureus (ATCC 25904) and Escherichia coli (NEWP0022) were purchased from Newman™ and NEWPROV™ Companies, respectively. Clinical S. aureus (from human intra-abdominal fluid, β-lactamase producer, mecA mediated methicillin resistance), and clinical Acinetobacter baumannii (from blood culture, resistant to amikacin, cefepime, ceftazidime, ceftriaxone, ciprofloxacin, imipenem, levofloxacin, meropenem, piperacillin-tazobactam and trimethoprim-sulfamethoxazole) were provided by the Center of Clinical Analysis of the University Hospital, Universidade Federal de Mato Grosso do Sul (Campo Grande-MS, Brazil). The antimicrobial activity was determined by broth microdilution method, as described by Manda et al. (2018) [22]. Initially, samples were solubilized in dimethyl sulfoxide (DMSO). Two-fold dilutions were performed in 96-well plates prepared with Mueller–Hinton broth to reach a final concentration of 4000 μg/mL to 31.3 μg/mL, with a 100 μL final volume in each well for plant extracts and phases. The isolated compounds (3, 10 and 18) were evaluated at concentrations ranging from 2000 to 15.6 μg/mL. For ampicillin the concentration ranged from 2000 to 15.6 μg/mL, and for ciprofloxacin from 100 to 0.78 μg/mL. Gentamicin was used as a positive control (60.0 to 0.5 μg/mL). The inoculums were overnight cultures of each bacterial species in Mueller–Hinton agar diluted in sterile saline solution (0.9%) to a cell density of approximately 108 CFU/mL (0.5 in McFarland scale), measured in a MS Tecnopon MCF-500 McFarland turbidimeter. This solution was diluted 1/10 in saline solution (0.9%) and 5 μL were added to each well containing the test samples. All experiments were performed in triplicate and the microdilution trays were incubated at 36ºC for 18 h. Then, 20 μL of an aqueous solution (0.5%) of triphenyltetrazolium chloride (TTC) were added to each well and the trays were again incubated at 36ºC for 2 h. In those wells where bacterial growth did occur, TTC changed from colorless to red. MIC was defined as the lowest concentration of each substance at which no color change occurred and was expressed in μg/mL. The culture medium was used as a negative control, and DMSO was used as a blank.

Synergistic interactions were evaluated using the checkerboard microtiter test, following the method described by Solarte et al. (2017) [23]. Serial two-fold dilutions of the extracts and phases were made vertically in 96-well plates prepared with Mueller–Hinton broth, to reach a concentration of 4000 μg/mL to 31.3 μg/mL, with a 50 μL final volume in each well. For the isolated compounds, the concentrations ranged from 2000 to 15.6 μg/mL. Aliquots (50 μL) of antibiotics solutions in Mueller–Hinton broth were added in each well, so the final concentrations varied horizontally from 100 to 0.05 μg/mL. For the assays with isolated compounds, the concentration of ampicillin ranged from 2000 to 0.98 μg/mL. Bacterial inoculums were prepared as mentioned above, and 5 μL were added to each well containing the test samples, then the plates were incubated at 36ºC for 18 h. After addition of TTC, MICs of the combinations were accessed, and fractional inhibitory concentration (FIC) and fractional inhibitory concentration index (FICI) were calculated by the formulae:


The FICI value was interpreted as: synergism (FICI ≤ 0.5), additive (0.5 < FICI ≤ 1), indifferent (1 < FICI ≤ 4), and antagonist (FICI > 4) [24,25,26].

Antibiofilm assay

Staphylococcus aureus ATCC 25904 (Newman) was grown on Muller-Hinton agar at 37ºC overnight. Bacterial suspensions with an optical density corresponding to 0.150 (approximately 3 × 108 CFU/mL) at 600 nm (OD 600) were prepared in sterile 0.9% NaCl solution and used in the assays.

Extracts and fractions of M. albicans were solubilized in DMSO at 6.25 and 25 mg/mL, providing a final tested concentration of 125 and 500 μg/mL, respectively. S. aureus biofilm formation was evaluated using crystal violet technique and planktonic bacterial growth was assessed by the difference between the OD 600 absorbance measured at the end and the beginning of incubation time. All assays were developed in 96-well microtiter plates of polystyrene, as described by Trentin et al. (2011) [27]. As negative control, the samples were replaced by 2% DMSO, and this condition was considered as 100% biofilm formation and bacterial growth, being used to compare the activity of samples. As positive control, samples were replaced by vancomycin (8 μg/mL).

All antibiofilm assays were performed at least in triplicate. The data were analyzed by Student's t-test in relation to the negative control (untreated samples) and a p-value ≤ 0.05 was considered to be significant.


Leaves (L) and stems (S) of M. albicans were macerated with ethanol to obtain the respective ethanol extracts of leaves (LEE) and stems (SEE). The EtOH extracts were subsequently partitioned between different solvents to give the corresponding hexane (LHxP and SHxP), CHCl3 (LCP and SCP), ethyl acetate (LEP and SEP) and hydromethanol (LHP and SHP) phases.

To investigate the antibacterial properties of M. albicans, the foregoing extracts, phases, and three isolated compounds present in most of these samples [gallic acid (3), quercitrin (10) and corosolic acid (18)] were assessed against reference strains of Staphylococcus aureus and Escherichia coli, and against clinical isolates of methicillin-resistant S. aureus (MRSA) and MDR Acinetobacter baumannii, both individually and in combination with antibiotics. Furthermore, the antibiofilm potential of extracts and their respective phases were evaluated against S. aureus. Antibiofilm properties of 3, 10 and 18 were not evaluated due to their limited amount.

Antimicrobial evaluations

As depicted in Table 1, SEE extract demonstrated moderate activity against the reference strain of S. aureus and MDR A. baumannii, with MIC values of 500 μg/mL, while LEE proved inactive against both strains (MIC = 1000 μg/mL). Both extracts were also inactive against E. coli and MRSA. Most of the phases resulting from the liquid–liquid partition of the bioactive extracts proved ineffective against E. coli and S. aureus, except for LEP, LHP, and SHP, which were moderately active against the Gram-positive reference bacterium. Regarding MRSA and MDR A. baumannii, the best results were observed for the SEP phase against both strains and LEP phase against A. baumannii strain (MIC values of 500 μg/mL).

Table 1 MIC values of M. albicans extracts, phases, and isolated compounds against bacterial strains

For reference strain E. coli, the isolated compounds 3, 10 and 18 were ineffective (MIC values ≥ 250) [6], while for S. aureus, only compounds 3 and 18 showed moderate activity (MIC values of 31.3 and 62.5 µg/ml, respectively). When evaluated against clinical bacteria, isolated compounds showed moderate to weak activity profiles, with MIC values ranging from ≥ 250 to 62.5 µg/ml against A. baumannii and from ≥ 500 to 250 µg/ml against MRSA.

Antibiofilm activity

Both Gram-positive and Gram-negative bacteria have the ability to adhere and develop biofilms, but staphylococcal species are most commonly associated with biofilm-related infections, accounting for approximately two-thirds of cases involving indwelling medical devices [28]. Taking this under consideration, and based on the previously observed antimicrobial activity (Table 1), we selected S. aureus, a well-known biofilm-forming strain [7, 29], to assess the potential of extracts and phases obtained from M. albicans in preventing biofilm formation (Fig. 1). The evaluated extracts LEE and SEE did not exhibit any significant activity against biofilm formation. However, upon fractionation, the stems fractions revealed the highest antibiofilm activity against S. aureus. Among these fractions, SCP, SHP and SEP particularly stood out for their effectiveness.

Fig. 1
figure 1

Biofilm formation by S. aureus ATCC 25904 treated with extracts and phases of Miconia albicans. A 125 µg/mL and B 500 µg/mL. Significant differences in comparison to negative control (2% DMSO) with p value ≤ 0.05 are represented by ** for biofilm formation and * for bacterial growth

At the highest concentration evaluated (500 μg/mL), except for LHxP, all samples inhibited biofilm formation. In this condition, the most active phases, for which S. aureus biofilm formation was suppressed, were SHP, SCP and LEP (allowing only 7.6 ± 1.4%, 9 ± 5.3%, and 41 ± 20% of biofilm formation, respectively) (Fig. 1).

At a concentration of 125 µg/mL, both SHP and SCP exhibited sustained activity, with SCP showing a particularly high rate of biofilm inhibition, by allowing only 13 ± 10% of biofilm formation to occur. It is worth noting that SEP maintained the inhibition rate of c. 50% at both tested concentrations. It is important to highlight that the most active phases, at the tested concentrations, did not exhibit any interference with bacterial growth (Fig. 1).

Synergistic effect

Extracts and phases were further assessed against clinical MRSA and MDR A. baumannii strains in combination with antibiotics currently used in therapy, ampicillin and ciprofloxacin, to which these bacteria have already shown to be resistant.

As depicted in Table 2, combinations of M. albicans extracts and phases with ampicillin revealed a synergistic effect against MRSA, except for LCP, LHxP and LEP, which showed an additive effect. Promising results were observed for the LEE extract, with a Fractional Inhibitory Concentration Index (FICI) value of 0.04, and a reduction of 32-fold in the LEE MIC value. Significant results were also observed for all extracts and phases from stems, particularly emphasizing the effectiveness of the SCP and SHP phases, both with FICI of 0.08, followed by the SEP phase and the SEE extract, with FICIs values of 0.13 and 0.14, respectively.

Table 2 Fractional inhibitory concentration (FIC) and FIC indices (FICI) of antibiotic-extracts/ phases pairs, against MRSA

When evaluated in combination with antibiotics against MDR A. baumannii, the extracts and phases demonstrated a notable enhancement in the activity of both ampicillin and ciprofloxacin (Table 3). All tested combinations showed synergism or additive effects, except for the combination of SEE and ampicillin, resulting in FICI = 2, indicating indifference.

Table 3 Fractional inhibitory concentration (FIC) and FIC indices (FICI) of antibiotic-extracts/ phases pairs, against A. baumannii

For the combination with ampicillin, the best activity profiles were observed for extracts and phases from leaves, especially for the non-polar phases LCP and LHxP, with FICI 0.28.

The most promising results against A. baumannii were observed for the combination of extracts and phases with the antibiotic ciprofloxacin. Except for the additive effect observed for the SEE extract, all other combinations showed a synergistic effect, with FICI values ranging from 0.13 to 0.5 (Table 3).

The isolated compounds 3, 10 and 18 did not show additive or synergistic effects (Tables 2 and 3).

Chemical profile

The chemical profiles of M. albicans extracts (LEE and SEE) and their respective phases were determined by HPLC–UV-MS (Fig. 2, Table 4), in which 21 metabolites were tentatively identified, based on retention time, online UV, and HRESIMS data, including mass spectrometric fragmentation patterns (MS and MS2). These data were compared with those of authentic standards, literature data, or both (Table 4).

Fig. 2
figure 2

HPLC–DAD-MS/MS (negative mode) profiles of ethanol extracts and phases of M. albicans. Peak numbers refer to compounds listed in Table 4. LEE = Leaves-ethanol extract. LCP = Leaves-chloroform phase. LEP = Leaves-ethyl acetate phase. LHP = Leaves-hydromethanolic phase. SEE = Stems-ethanol extract. SCP = Stems-chloroform phase. SEP = Stems-ethyl acetate phase. SHP = Stems-hydromethanolic phase

Table 4 HPLC–UV-MS data of annotated compounds from extracts and phases of M. albicans leaves and stems. + : presence; -: absence

The retention time and mass spectrum data, along with the peak assignments for compounds annotated and/or identified (using negative ionization mode for compounds 119 and positive ionization mode for 20 and 21, non-ionizable in negative mode) are described in Table 4. The identified metabolites consist of gallic and ellagic acid derivatives, flavonol glycosides, triterpenes and pheophorbides.

Compound 1 was annotated as a tetramer of hexose based on literature data [30], while 2 showed MS/MS compatible to a quinic acid pattern [31]. Compound 3 was assigned to gallic acid, based on its [M–H] ion at m/z 169.0147 and its MS/MS was in accordance with a typical gallic acid pattern [31]. Additionally, results revealed the presence of three gallic acid derivatives, with 5 assigned to ethyl gallate [31], while 4 and 6 were annotated as unknown gallic acid derivatives [32].

Five compounds (7–11) were characterized as flavonols, based on the mass spectra of their deprotonated glycosides and the presence of ions corresponding to their deprotonated aglycones at m/z 300/301 (for quercetin) and 315 (for isorhamnetin), generated by the loss of the sugar units. Furthermore, fragment ions at m/z 271 [Y0-H2CO] and 255 [Y0–CO-H2O] from fragmentation of quercetin, and m/z 315 [Y0-CH2O] and 299 [Y0–CO-H2O] from fragmentation of isorhamnetin were detected [33,34,35,36]. Peak 7 (m/z 615.1000, C28H24O16) showed fragment ions at m/z 301/300 and 169, compatible with a quercetin hexoside derivative. The fragment ion at 169 Da indicated the presence of a galloyl group, allowing the annotation of 7 as a quercetin-galloyl-hexoside derivative [15].

Compounds 12, 13, 16 and 17 were assigned to ellagic acid derivatives. The [M-H]- ions of 13 and 17 exceeded that of ellagic acid by 28 and 42 Da, corresponding to the extra two and three methyl groups, respectively. Their fragmentation patterns were characterized by a loss of 15 Da [M-CH3-H], attributed to the loss of the methyl radical. These compounds were thus tentatively identified as dimethylellagic and trimethylellagic acids, respectively. Compounds 12 and 16 were annotated as di-O-methyl-O-pentosyl ellagic acid and methyl ellagic acid bearing a methylenedioxy substituent, respectively [31, 37].

Compounds 18 and 19 showed peaks of deprotonated ions at m/z 471.3615 and 455.3656, compatible with molecular formulae C30H48O4 and C30H48O3, respectively. These compounds were identified as the triterpenes corosolic acid (18) and betulinic acid (19), based on the analysis of their MS data and comparison with reference compounds. Compounds 14 and 15 also presented deprotonated ions at m/z 503.3398 and 487.3452, in accordance with molecular formulae of compounds containing 30 carbons, therefore annotated as triterpenes.

Compounds 20 and 21 were observed exclusively in positive ionization mode, with protonated ions at m/z 593.2780 and m/z 621.3160, compatible with the molecular formulae C35H36N4O5 and C37H40N4O5, respectively. These compounds were identified as pheophorbide B and pheophorbide A ethyl ester, respectively, based on the analysis of their MS data and retention time, as well as by comparison with data of authentic samples isolated and identified from the same extract, together with literature report [38].

The chemical composition of both hexane phases was investigated using gas chromatography coupled to mass spectrometry (GC–MS) (Fig. 3). The identification of the constituents was performed by comparing the mass spectra obtained with those of the equipment database (Wiley 7 lib and Nist 08 lib), literature data [39], and by using authentic standards.

Fig. 3
figure 3

GC–MS profiles of hexane phases of M. albicans. Peak numbers refer to compounds listed in Table 5. A LHxP: Leaves-hexane phase; B SHxP: Stems-hexane phase

Eleven major compounds were identified in the hexane phases (LHxP and SHxP) as belonging to the classes of triterpenes, steroids, fatty alcohol, and tocopherol (Table 5, Fig. 3). The identification of these compounds was carried out by analyzing mass data, retention time, fragmentation pattern, and comparison with data obtained from isolated compounds and published literature [39].

Table 5 Main metabolites identified by CG-MS in the hexane phases of M. albicans. LHxP: Leaves-hexane phase; SHxP: Stems-hexane phase. + : presence; -: absence

Compounds 10, 18–21, 23, 25, 28, 29 and 31 were isolated as described on item “Extraction and isolation” (Materials and methods) and identified by analysis of 1H and 13C NMR data, provided in the Supplementary material.


The extract and phases of M. albicans obtained from stems showed the best activity profile against Gram-positive bacteria, when tested against the reference strain of S. aureus, in the inhibition of biofilm formation, and in synergism with antibiotics against MRSA.

In the evaluation of the antimicrobial action, the SEE extract displayed the most potent activity, with a MIC of 500 µg/mL against the reference strain of S. aureus. Identical MIC values were also observed for LEP, LHP, and SHP phases. When tested against clinical bacteria, the SEP phase showed the best activity against both resistant clinical strains MRSA and A. baumannii (MIC of 500 µg/mL) [6, 40].

The chemical profile of the SEP phase analyzed by HPLC–MS revealed the presence of flavonoids quercitrin (10) and isorhamnetin-O-deoxyhexoside (11), as well as gallic acid derivatives (3–5) as major constituents. In addition to their widely known antioxidant properties, flavonoids and aromatic compounds have shown promising antimicrobial activities [41,42,43], including their ability to inhibit biofilm formation by Streptococcus mutans, such as the antibiofilm activity exerted by quercitrin (10) against this microorganism [44]. Antimicrobial activities were previously reported for gallic acid (3) against Escherichia coli ATCC25922, Enterococcus faecalis OS4 and Salmonella Typhi MD17 [45], with MIC values of c. 200 µg/mL, while ethyl gallate (5) inhibited Shigella dysenteriae CMCC 51105, Escherichia coli ATCC 25922, Salmonella typhimurium CMCC 50115, S. aureus, and S. albus with MIC of 240 µg/mL [46], besides acting in synergy with tetracycline against MRSA [47].

Previous studies on Miconia species have reported weak antimicrobial activity of leaf extracts from M. cabucu, M. stenostachya e M. rubuginosa against S. aureus, S. epidermidis, Candida albicans, Micrococcus luteus, Bacillus subtilis, and B. cereus, with MIC values ranging from 1,500 to 7,500 µg/mL [48]. A similar activity profile was observed for M. latecrenata, which inhibited the growth of S. aureus and P. aeruginosa with MIC values of 300 µg/mL and 2,500 µg/mL, respectively [49].

One of the mechanisms by which commensal bacteria, like S. aureus, can establish persistent and challenging infections that are difficult to eradicate is through the formation of bacterial biofilms. The ability of S. aureus to form biofilms has led to cases of persistent chronic infections, particularly in host tissues where implanted materials such as valves or catheters are present, resulting in serious conditions like osteomyelitis, endocarditis, and infections in prosthetic joints, pacemakers, and other implanted devices. Bacterial cells enclosed in polymer-based matrix promote an increase in resistance to antibiotics and even immune defense mechanisms, making these infections particularly challenging to treat and eliminate [50].

The antibiofilm potential of M. albicans extracts and phases was evaluated against S. aureus, in which the stem phases SCP and SHP demonstrated promising antibiofilm inhibitory activity, allowing only 9 ± 5.3% and 7.6 ± 14% of biofilm formation at 500 µg/mL. The SCP phase also stands out for its remarkable antibiofilm activity, particularly for being the only sample to maintain strong efficacy even at the lowest concentration tested (125 µg/mL), allowing the development of only c.13% of biofilm formation. Analysis of the chemical composition of SCP revealed a diverse chemical profile, with the presence of ellagic acid (12, 13, 16, and 17) and flavonoid (10 and 11) derivatives as major constituents, in addition to triterpenes (14, 15 and 18). Literature reports antibiofilm properties of some compounds that have been detected in SCP, such as ellagic acid derivatives (glycosides) against S. aureus [51]. Previously isolated from Amphiblemma monticola (Melastomataceae) and similar to compound 13, 3,4′-di-O-methylellagic acid showed the best anti-staphylococcal activity against MRSA and methicillin-sensitive S. aureus (MSSA), with MIC values ranging from 16 to 32 μg/mL [52]. Corosolic acid (18) has been reported to exhibit activity against the formation of P. aeruginosa biofilm, and showed synergistic effects with ciprofloxacin, enhancing the susceptibility of bacterial biofilm to this antibiotic [53]. In addition, corosolic acid has demonstrated the ability to increase the susceptibility of resistant Klebsiella pneumoniae to carbapenem antibiotics [54]. In terms of chemical composition, the SHP phase exhibited the least complex profile among the analyzed samples, and shares compounds 1, 3, 10, 11 and 18 with the SCP phase.

Although several studies have proved the antimicrobial properties of isolated compounds from natural sources, promising results have been obtained for plant extracts in combination to antibiotics as a synergistic approach in combating MDR bacteria [55].

Indeed, antibacterial combination therapies have become an important treatment choice for patients with multidrug resistant bacterial infections in clinical settings. Furthermore, when current antibiotics with a single target are employed, the large dosages needed for effectiveness frequently result in bioavailability issues, undesirable side effects, and the emergence of resistance. High doses of a single product may not be necessary if multiple targets could be achieved using antibacterial adjuvants [6]. Adjuvants provide a complementary and alternative approach to the discovery of novel antibiotics by providing a way to both prevent the development of resistance and restore the effectiveness of already prescribed medications. The criteria for the development of novel antimicrobials are strict and involve the thorough evaluation of efficacy and safety indexes, including the comparison of these indexes with those of the initial successful natural product drugs, primarily derived from microorganisms. In addition, treatment of bacterial infections usually requires doses on the gram scale—much higher than other drugs. Therefore, toxicity and efficacy parameters are tough to match for new molecules, which reinforces the importance of initiatives aiming at preserving the currently existing drugs as much as possible [56].

Biologically active plant-derived products have the ability to combat antibiotic resistance and act in synergism with existing antibiotics. One such example is the essential oil obtained from Pectis substriata (Asteraceae), which has demonstrated a synergistic effect when combined with antibiotics against clinical drug-resistant Staphylococcus warneri. Additionally, it has shown additive effects against pathogens, such as S. aureus and S. intermedius [57]. Another example is the antibacterial activity of the dichloromethane extract obtained from the leaves of the shea butter tree (Vitellaria paradoxa C.F. Gaertn.—Sapotaceae). This extract combined with ampicillin, oxacillin, and nafcillin exhibited synergism against MRSA, by specifically targeting beta-lactamase enzymes [58]. Ilanko et al. (2019) [59] have studied the antimicrobial properties of Moringa oleifera (Moringaceae) extracts (leaf, pulp and seeds extracts) against a panel of bacterial triggers of autoimmune inflammatory diseases, alone and in combination with various antibiotics, achieving good results of synergistic or additive effects. Hence, once natural products with limited antimicrobial activity can act as potential allies in the search for novel antimicrobials through synergistic interactions with commercial antibiotics, the extracts and fractions of M. albicans were also assessed in this context.

Methicillin resistant S. aureus (MRSA) has become a major nosocomial pathogen [60], ranking among the main etiologic agents of hospital-associated bloodstream infections and nosocomial pneumonia, and representing c. 60% of S. aureus isolated from hospitalized patients [61]. Clinical cases of persistent infections have increased worldwide, making this microorganism an important target for the search for therapeutic alternatives, particularly crucial for hospitalized patients or those receiving intensive care.

All extracts and phases of M. albicans showed synergistic or additive effect with the antibiotic ampicillin against clinical MRSA, with FICI values ranging from 1 to 0.04. In addition to restoring the ampicillin activity, it is noteworthy that the combinations also resulted in a significant reduction in the MIC of this antibiotic, which ranged from approximately 80 to 160-fold. Plants of the same genus also showed synergistic activity against reference strains of S. aureus (ATCC29213) by a combination of the organic extract (DCM/MeOH) obtained from the leaves of M. latecrenata with ampicillin, with FICI 0.4, and combination of the ethyl acetate phase with tetracycline against P. aeruginosa (ATCC 27853), with FICI 0.3 [49]. In general, the combination of SEE and its phases with ampicillin demonstrated greater efficacy against MRSA. However, the best activity was observed for LEE with FICI 0.04, reducing the MIC of this antibiotic by 160-fold, and that of the LEE extract individually by 32-fold. It is noteworthy that LEE presented the most complex chemical profile among the analyzed samples, which revealed the presence of a diverse array of compounds, such as glycosylated flavonoids (7–10) as major constituents, in addition to quinic acid (2), gallic acid (3), ellagic acid derivatives (13,16- 17), triterpenes (18–19), and pheophorbides (20–21).

Antimicrobial activities have already been reported for some of the aforementioned compounds, such as quinic acid (2), with a prominent bacteriostatic and bactericidal action against Escherichia coli (IFO 3301), with the highest activity against this bacterium achieved by the combination of quinic acid with caffeic acid [62]. Flavonoid glucosides, like compounds 7–11 [63], and their respective aglycones, such as quercetin, are also often reported as membrane-disrupting agents against bacterial cells [42]. A previous review regarding the physicochemical parameters and antibacterial activities of 66 flavonoids against S. aureus pointed out that flavonoids primary sites of action on Gram-positive bacteria were in the cell membrane, which probably involved phospholipid bilayer degradation, suppression of the respiratory chain or ATP generation, among other mechanisms [41]. Flavonoids bearing galloyl moieties, such as 7, were isolated from Woodfordia uniflora (Lythraceae) and showed significant antibacterial properties against MRSA, by inhibiting biofilm formation, and also by acting synergistically with methicillin [13]. The antibacterial activity of triterpenes, like 14, 15, 18, 19, 23 and 29–31, against Gram-positive bacteria has been frequently described. A systematic review on activity of pentacyclic triterpenoids against S. aureus reported that their remarkable antistaphylococcal properties are related to modifications on membrane permeability through hydrophobic interaction and accumulation of these compounds in the bacterial membrane [64].

Also deserves attention the adjuvant properties showed by SCP and SHP phases against MRSA, as they present FICI 0.08, indicating a significant reduction of the MIC of ampicillin by 80-fold and of the phases by 16-fold. In addition, these phases showed remarkable antibiofilm activity profiles.

MDR A. baumannii, at the top of the WHO list of priorities for the development of novel antimicrobials, is considered a critical microorganism because it is often associated with nosocomial infection outbreaks, with a high incidence in intensive care units [65]. This particular bacterium which has been isolated from hospitals worldwide, including Brazil, is associated with an approximate 30% increase in mortality risk among hospitalized patients infected with A. baumannii [66].

In the present study, all combinations of M. albicans extracts and phases with ampicillin and ciprofloxacin proved to be active against clinical MDR A. baumanii. Contrary to the observations with MRSA, the most promising results in combination with ampicillin were obtained with the phases originating from the leaves of M. albicans, namely LHxP and LCP, with FICI values of 0.28, while LEE, LHP and LEP showed additivity in combination with this antibiotic. However, the most effective combination was observed with ciprofloxacin, wherein all samples, except for SEE, acted in synergism, restoring the activity of this drug. Regarding the stem samples in combination with this antibiotic, SEP, SCP and SHxP proved the most active, with FICI values of 0.25, 0.25 and 0.27, respectively. For the combination of leaves samples with ciprofloxacin, FICI values ranged from 0.13 to 0.38, and the best result was achieved for LHxP. It is important to highlight that for carpabenem-resistant A. baumannii, such as the clinical strain evaluated in this work, treatment options are limited and also face important pharmacokinetic drawbacks [67].

The chemical profile of LHxP revealed squalene (23) as its major constituent (Fig. 3), which was only detected in this phase. This compound, which is regarded as a precursor of triterpenes, has been reported to exhibit antimicrobial activity against Mycobacterium tuberculosis H37Ra with MIC of 100 µg/mL [68]. Regarding the triterpene α-Amyrin (31), the second most abundant compound in LHxP (Fig. 3), literature describes its antibacterial activity against MSSA and MRSA, with MIC of 64 µg/mL [69].

Analysis of the chemical profile of the LCP phase by HPLC–MS revealed the presence of O-methyl-methylenedioxi ellagic acid (16) and tri-O-methyl ellagic acid (17). The di-O-methyl-O-pentosyl ellagic acid derivative has shown antibacterial activities against E. coli (ATCC25922), Salmonella typhi MD17, Enterococcus faecalis OS4, S. aureus, and P. mirabilis (ATCC 7002), with MICs ranging from 19.53 to 312.50 µg/mL [70]. Ellagic acid previously isolated from Miconia myriantha [71] also showed moderate anti-A. baumannii activity, inhibiting 67% of bacterial growth at 250 µg/mL [72].

As a complementary investigation, three key compounds found in the chemical profile of the majority of samples (Table 4), representing the main classes of secondary metabolites present in M. albicans extracts and phases –namely gallic acid (3), quercitrin (10), and corosolic acid (18)–, were selected and evaluated individually and in combination with ampicillin and ciprofloxacin against the bacterial strains (Table 1). For plant extracts and phases, the antibacterial activity is considered significant if MIC values are below 100 µg/mL, moderate if 100 ≤ MICs ≤ 625 µg/mL, and weak if MICs > 625 µg/mL [6, 40]. On the other hand, the antimicrobial activity of an isolated phytochemical has been defined as significant when MIC is below 10 µg/mL, moderate when 10 µg/mL < MIC < 100 µg/mL, and weak when MIC > 100 µg/mL [6, 73]. For S. aureus reference strain, compounds 3 and 18 showed moderate activity (MIC values of 31.3 and 62.5 µg/ml, respectively), while all the tested compounds proved ineffective against E. coli. Similarly, none of the compounds showed significant activities against clinical bacteria, with MIC values ranging from ≥ 500 to 250 µg/ml against MRSA and from ≥ 250 to 62.5 µg/ml against A. baumannii. When combined with antibiotics, these isolated compounds did not demonstrate any additive or synergistic effects (Tables 2 and 3). The scientific literature reports studies with analogous findings, where extracts and/or phases have shown superior activity compared to isolated compounds. Plant extracts and phases usually consist in complex mixtures of secondary metabolites, that can primarily act through multiple targets, exerting significant synergistic effects [6, 55, 74].


Fighting microbial resistance requires a multifaceted approach that encompasses accurate diagnosis, appropriated prescription and adherence to treatment, proper disposal of antimicrobials, and significant investment in the development of new treatments. In this context, the search for new resistance-modifying agents finds in the vast biodiversity of plants an important source to be explored, in order to contribute to the development of new combinations that can act as adjuvants in the fight against resistant infections.

The extracts and phases obtained from M. albicans showed notable antibacterial properties, with specific emphasis on the activities of LEE extract and various phases, namely SCP, SHP, LEP e LHxP. Among these, SCP demonstrated the most effective antibiofilm activity and exerted synergistic effects when combined with ampicillin (AMP) against MRSA, and with ciprofloxacin (CIP) against A. baumannii. A synergic action against MRSA was also revealed by a combination of SHP with AMP, while synergistic interactions against the former microorganism were also observed for combinations of LEP with CIP and of LHxP with either AMP or CIP. In terms of the extracts, LEE showed the best activity profile against MRSA when combined with AMP. It is also worth to mention that extracts and phases from M. albicans showed higher antibacterial properties when compared to the isolated compounds gallic acid, quercitrin and corosolic acid, present in most of the samples.

The present findings provide evidence of the remarkable antimicrobial properties exhibited by M. albicans, particularly in its role as an adjuvant for antibiotic drugs, with potentialities for the development of novel efficacious agents aimed at treating and preventing the dissemination of antibiotic-resistant bacterial infections. Further comprehensive toxicological studies are required for safety purposes.

Availability of data and materials

All data generated or analysed during this study are included in this published article [and its supplementary information files].



Leaves-ethanol extract


Leaves-hexane phase


Leaves-ethyl acetate phase


Leaves-chloroform phase


Leaves-hydromethanolic phase


Stems-ethanol extract


Stems-hexane phase


Stems-ethyl acetate phase


Stems-chloroform phase


Stems-hydromethanolic phase


High-Performance Liquid Chromatography coupled with Diode Array Detector and tandem Mass Spectrometry


Electrospray ionization


Gas Chromatography Coupled to Mass Spectrometry


Nuclear Magnetic Resonance


Multi-drug resistant


Methicillin-resistant Staphylococcus aureus

CDCl3 :

Deuterated chloroform


Deuterated methanol


Ethyl acetate




Relative retention


Colony-forming unit


Triphenyltetrazolium chloride


Minimum inhibitory concentration


Fractional Inhibitory Concentration


Fractional Inhibitory Concentration index


Dimethyl sulfoxide






High Resolution Electrospray Ionization Mass Spectrometry


Tandem Mass Spectrometry


Methicillin-Sensitive S. aureus




  1. Murray CJ, Ikuta KS, Sharara F, Swetschinski L, Robles Aguilar G, Gray A, et al. Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. Lancet. 2022;399:629–55.

    CAS  Google Scholar 

  2. Saleem M, Nazir M, Ali MS, Hussain H, Lee YS, Riaz N, et al. Antimicrobial natural products: an update on future antibiotic drug candidates. Nat Prod Rep. 2010;27:238–54.

    CAS  PubMed  Google Scholar 

  3. United Nations. Reduce pollution to combat ‘superbugs’ and other anti-microbial resistance | UN News. 2023. Acessed 4 May 2023. Available from:

  4. Chassagne F, Samarakoon T, Porras G, Lyles JT, Dettweiler M, Marquez L, et al. A systematic review of plants with antibacterial activities: a taxonomic and phylogenetic perspective. Front Pharmacol. 2021;11: 586548.

    PubMed  PubMed Central  Google Scholar 

  5. Mickymaray S. Efficacy and mechanism of traditional medicinal plants and bioactive compounds against clinically important pathogens. Antibiot. 2019;8:257.

    CAS  Google Scholar 

  6. Simões M, Bennett RN, Rosa EAS. Understanding antimicrobial activities of phytochemicals against multidrug resistant bacteria and biofilms. Nat Prod Rep. 2009;26:746–57.

    PubMed  Google Scholar 

  7. Silva LN, Zimmer KR, Macedo AJ, Trentin DS. Plant natural products targeting bacterial virulence factors. Chem Rev. 2016;116:9162–236.

    CAS  PubMed  Google Scholar 

  8. Alam M, Bano N, Ahmad T, Sharangi AB, Upadhyay TK, Alraey Y, et al. Synergistic role of plant extracts and essential oils against multidrug resistance and Gram-negative bacterial strains producing extended-spectrum beta-lactamases. Antibiot. 2022;11:855.

    CAS  Google Scholar 

  9. Buenz EJ, Bauer BA, Schnepple DJ, Wahner-Roedler DL, Vandell AG, Howe CL. A randomized Phase I study of Atuna racemosa: A potential new anti-MRSA natural product extract. J Ethnopharmacol. 2007;114:371–6.

    PubMed  Google Scholar 

  10. Hemaiswarya S, Kruthiventi AK, Doble M. Synergism between natural products and antibiotics against infectious diseases. Phytomedicine. 2008;15:639–52.

    CAS  PubMed  Google Scholar 

  11. Tyers M, Wright GD. Drug combinations: a strategy to extend the life of antibiotics in the 21st century. Nat Rev Microbiol. 2019;17:141–55.

    CAS  PubMed  Google Scholar 

  12. Efferth T, Koch E. Complex interactions between phytochemicals. The multi-target therapeutic concept of phytotherapy. Curr Drug Targets. 2010;12:122–32.

    Google Scholar 

  13. Yu Z, Tang J, Khare T, Kumar V. The alarming antimicrobial resistance in ESKAPEE pathogens: Can essential oils come to the rescue? Fitoterapia. 2020;140: 104433.

    CAS  PubMed  Google Scholar 

  14. Valdivieso-Ugarte M, Gomez-Llorente C, Plaza-Díaz J, Gil Á. Antimicrobial, antioxidant, and immunomodulatory properties of essential oils: a systematic review. Nutrients. 2019;11:2786.

    CAS  PubMed  PubMed Central  Google Scholar 

  15. Quintans-Júnior LJ, Gandhi SR, Passos FRS, Heimfarth L, Pereira EWM, Monteiro BS, et al. Dereplication and quantification of the ethanol extract of Miconia albicans (Melastomaceae) by HPLC-DAD-ESI-/MS/MS, and assessment of its anti-hyperalgesic and anti-inflammatory profiles in a mice arthritis-like model: Evidence for involvement of TNF-α. I J Ethnopharmacol. 2020;258:112938.

  16. Lima TC, Matos SS, Carvalho TF, Silveira-Filho AJ, Couto LPSM, Quintans-Júnior LJ, et al. Evidence for the involvement of IL-1β and TNF-α in anti-inflammatory effect and antioxidative stress profile of the standardized dried extract from Miconia albicans Sw. (Triana) Leaves (Melastomataceae). J Ethnopharmacol. 2020;259:112908.

    CAS  PubMed  Google Scholar 

  17. Pieroni LG, De Rezende FM, Ximenes VF, Dokkedal AL. Antioxidant activity and total phenols from the methanolic extract of Miconia albicans (Sw.) Triana Leaves. Molecules. 2011;16:9439.

  18. Alexandre A, de Castro F, Alves Batista F, Rodrigues Santos SA, Mendes F da S, Gonçalves G, et al. Chemical profile and anxiolytic- and anticonvulsant-like effects of Miconia albicans (Sw.) Triana (Melastomataceae) leaves in adult zebrafish. Pharmacogn Mag. 2021;17:146.

  19. de Cássia Lemos Lima R, Kongstad KT, Kato L, José das Silva M, Franzyk H, Staerk D. High-resolution PTP1B inhibition profiling combined with HPLC-HRMS-SPE-NMR for identification of PTP1B inhibitors from Miconia albicans. Molecules. 2018;23:1755.

  20. Serpeloni JM, Mazzaron Barcelos GR, Prates Mori M, Yanagui K, Vilegas W, Aparecida Varanda E, et al. Cytotoxic and mutagenic evaluation of extracts from plant species of the Miconia genus and their influence on doxorubicin-induced mutagenicity: an in vitro analysis. Exp Toxicol Pathol. 2011;63:499–504.

    CAS  Google Scholar 

  21. de Souza EPBSS, Gomes MVLD, dos Santos Lima B, Silva LAS, Shanmugan S, Cavalcanti MD, et al. Nerolidol-beta-cyclodextrin inclusion complex enhances anti-inflammatory activity in arthritis model and improves gastric protection. Life Sci. 2021;265:118742.

  22. Manda BR, Prasad AN, Thatikonda NR, Lacerda V, Barbosa LR, Santos H, et al. Synthesis, antibacterial and antitubercular evaluation of cardanol and glycerol-based β-amino alcohol derivatives. J Braz Chem Soc. 2018;29:639–48.

    CAS  Google Scholar 

  23. Solarte AL, Astorga RJ, Aguiar F, Galán-Relaño Á, Maldonado A, Huerta B. Combination of antimicrobials and essential oils as an alternative for the control of Salmonella enterica multiresistant strains related to foodborne disease. Foodborne Pathog Dis. 2017;14:558–63.

    CAS  PubMed  Google Scholar 

  24. Silva DM, da Costa PA, Ribon AOB, Purgato GA, Diaz-Muñoz G, Diaz MAN. Plant extracts display synergism with different classes of antibiotics. An Acad Bras Cienc. 2019;91: e20180117.

    PubMed  Google Scholar 

  25. Ahumada-Santos YP, Soto-Sotomayor ME, Báez-Flores ME, Díaz-Camacho SP, López-Angulo G, Eslava-Campos CA, et al. Antibacterial synergism of Echeveria subrigida (B. L. Rob & Seaton) and commercial antibiotics against multidrug resistant Escherichia coli and Staphylococcus aureus. Eur J Integr Med. 2016;8:638–44.

  26. Lim A, Subhan N, Jazayeri JA, John G, Vanniasinkam T, Obied HK. Plant Phenols as Antibiotic Boosters: In Vitro interaction of olive leaf phenols with ampicillin. Phyther Res. 2016;30:503–9.

  27. Trentin DDS, Giordani RB, Zimmer KR, Da Silva AG, Da Silva MV, Correia MTDS, et al. Potential of medicinal plants from the Brazilian semi-arid region (Caatinga) against Staphylococcus epidermidis planktonic and biofilm lifestyles. J Ethnopharmacol. 2011;137:327–35.

    PubMed  Google Scholar 

  28. Khatoon Z, McTiernan CD, Suuronen EJ, Mah TF, Alarcon EI. Bacterial biofilm formation on implantable devices and approaches to its treatment and prevention. Heliyon. 2018;4: e01067.

    PubMed  PubMed Central  Google Scholar 

  29. Dauros-Singorenko P, Wiles S, Swift S. Staphylococcus aureus biofilms and their response to a relevant in vivo iron source. Front Microbiol. 2020;11: 509525.

    PubMed  PubMed Central  Google Scholar 

  30. Demenciano SC, Lima e Silva MCB, Farias Alexandrino CA, Kato WH, de Oliveira Figueiredo P, Garcez WS, et al. Antiproliferative activity and antioxidant potential of extracts of Garcinia gardneriana. Molecules. 2020;25:3201.

  31. Chang Z, Jian P, Zhang Q, Liang W, Zhou K, Hu Q, et al. Tannins in: Terminalia bellirica inhibit hepatocellular carcinoma growth by regulating EGFR-signaling and tumor immunity. Food Funct. 2021;12:3720–39.

  32. Singh A, Bajpai V, Kumar S, Sharma KR, Kumar B. Profiling of gallic and ellagic acid derivatives in different plant parts of Terminalia arjuna by HPLC-ESI-QTOF-MS/MS. Nat Prod Commun. 2016;11:239–44.

    PubMed  Google Scholar 

  33. Wang J, Jia Z, Zhang Z, Wang Y, Liu X, Wang L, et al. Analysis of chemical constituents of Melastoma dodecandrum lour. By UPLC-ESI-Q-Exactive Focus-MS/MS Molecules. 2017;22:476.

    PubMed  Google Scholar 

  34. Li ZH, Guo H, Xu W Bin, Ge J, Li X, Alimu M, et al. Rapid identification of flavonoid constituents directly from PTP1B inhibitive extract of raspberry (I L.) leaves by HPLC-ESI-QTOF-MS-MS. J Chromatogr Sci. 2016;54:805–10.

  35. Tiberti LA, Yariwake JH, Ndjoko K, Hostettmann K. On-line LC/UV/MS analysis of flavonols in the three apple varieties most widely cultivated in Brazil. J Braz Chem Soc. 2007;18:100–5.

    CAS  Google Scholar 

  36. Fabre N, Rustan I, De Hoffmann E, Quetin-Leclercq J. Determination of flavone, flavonol, and flavanone aglycones by negative ion liquid chromatography electrospray ion trap mass spectrometry. J Am Soc Mass Spectrom. 2001;12:707–15.

    CAS  PubMed  Google Scholar 

  37. Khallouki F, Haubner R, Hull WE, Erben G, Spiegelhalder B, Bartsch H, et al. Isolation, purification and identification of ellagic acid derivatives, catechins, and procyanidins from the root bark of Anisophyllea dichostyla R. Br Food Chem Toxicol. 2007;45:472–85.

    CAS  PubMed  Google Scholar 

  38. Vencl FV, Gómez NE, Ploss K, Boland W. The chlorophyll catabolite, pheophorbide A, confers predation resistance in a larval tortoise beetle shield defense. J Chem Ecol. 2009;35:281.

    CAS  PubMed  PubMed Central  Google Scholar 

  39. Crevelin EJ, Turatti ICC, Crotti AEM, Veneziani CS, Lopes JLC, Lopes NP, et al. Identification of biologically active triterpenes and sterols present in hexane extracts from Miconia species using high-resolution gas chromatography. Biomed Chromatogr. 2006;20:827–30.

    CAS  PubMed  Google Scholar 

  40. Wamba BEN, Nayim P, Mbaveng AT, Voukeng IK, Dzotam JK, Ngalani OJT, et al. Syzygium jambos displayed antibacterial and antibiotic-modulating activities against resistant phenotypes. Evidence-based Complement Altern Med. 2018;2018:5124735.

    Google Scholar 

  41. Yuan G, Guan Y, Yi H, Lai S, Sun Y, Cao S. Antibacterial activity and mechanism of plant flavonoids to gram-positive bacteria predicted from their lipophilicities. Sci Reports. 2021;11:1–15.

    Google Scholar 

  42. Rafał IG, Króliczewski BJ, Górniak I, Bartoszewski R, Króliczewski ÁJ. Comprehensive review of antimicrobial activities of plant flavonoids. Phytochem Rev. 2018;18:241–72.

    Google Scholar 

  43. Bylka W, Matlawska I, Pilewski NA. Natural Flavonoids as Antimicrobial Agents JANA. 2004;7:24–31.

    Google Scholar 

  44. Hasan S, Singh K, Danisuddin M, Verma PK, Khan AU. Inhibition of major virulence pathways of Streptococcus mutans by quercitrin and deoxynojirimycin: a synergistic approach of infection control. PLoS One. 2014;9:91736.

    Google Scholar 

  45. El-Hawary SS, Mohammed R, AbouZid S, Ali ZY, El-Gendy AO, Elwekeel A. In-vitro cyclooxygenase inhibitory, antioxidant and antimicrobial activities of phytochemicals isolated from Crassula arborescens (Mill.) Willd. Int J Appl Res Nat Prod. 2016;9:8–14.

  46. Zhong L, Peng L, Fu J, Zou L, Zhao G, Zhao J. Phytochemical, antibacterial and antioxidant activity evaluation of Rhodiola crenulata. Molecules. 2020;25:3664.

    CAS  PubMed  PubMed Central  Google Scholar 

  47. Mar Soe W, Lin Myint N, Chu Sing L, K. Sakharkar M, Hock Tang T, R. Sakharkar K. Ethyl gallate as a combination drug can overcome resistance in MRSA. Lett Drug Des Discov. 2010;8:65–8.

  48. Rodrigues J, Michelin DC, Rinaldo D, Zocolo GJ, Dos Santos LC, Vilegas W, et al. Antimicrobial activity of Miconia species (Melastomataceae). J Med Food. 2008;11:120–6.

    CAS  PubMed  Google Scholar 

  49. Rodrigues LA, Almeida A das C, Gontijo DC, Salustiano IV, Almeida AA, Brandão GC, et al. Antibacterial screening of plants from the Brazilian Atlantic Forest led to the identification of active compounds in Miconia latecrenata (DC.) Naudin. Nat Prod Res. 2021;35:5904–8.

  50. Lister JL, Horswill AR. Staphylococcus aureus biofilms: Recent developments in biofilm dispersal. Front Cell Infect Microbiol. 2014;4:178.

    PubMed  PubMed Central  Google Scholar 

  51. Fontaine BM, Nelson K, Lyles JT, Jariwala PB, García-Rodriguez JM, Quave CL, et al. Identification of ellagic acid rhamnoside as a bioactive component of a complex botanical extract with anti-biofilm activity. Front Microbiol. 2017;8:496.

    PubMed  PubMed Central  Google Scholar 

  52. Nzogong RT, Ndjateu FST, Ekom SE, Fosso JAM, Awouafack MD, Tene M, et al. Antimicrobial and antioxidant activities of triterpenoid and phenolic derivatives from two Cameroonian Melastomataceae plants: Dissotis senegambiensis and Amphiblemma monticola. BMC Complement Altern Med. 2018;18:1–11.

    Google Scholar 

  53. Garo E, Eldridge GR, Goering MG, Pulcini EDL, Hamilton MA, Costerton JW, et al. Asiatic acid and corosolic acid enhance the susceptibility of Pseudomonas aeruginosa biofilms to tobramycin. Antimicrob Agents Chemother. 2007;51:1813–7.

    CAS  PubMed  PubMed Central  Google Scholar 

  54. Zhou Y, Lv X, Chen M, Guo Y, Ding R, Liu B, et al. Characterization of corosolic acid as a KPC-2 inhibitor that increases the susceptibility of KPC-2-Positive bacteria to carbapenems. Front Pharmacol. 2020;11:1047.

    CAS  PubMed  PubMed Central  Google Scholar 

  55. Wagner H, Ulrich-Merzenich G. Synergy research: Approaching a new generation of phytopharmaceuticals. Phytomedicine. 2009;16:97–110.

    CAS  PubMed  Google Scholar 

  56. World Health Organization. Strategic priorities on antimicrobial resistance. 2022. Accessed 4 May 2023.

  57. De Jesus GS, Micheletti AC, Takahashi KM, Matayoshi T, Pott A, Yoshida NC. Antimicrobial potential of Pectis substriata essential oil (Asteraceae) against drug-resistant Staphylococcus strains. An Acad Bras Cienc. 2020;92:1–10.

    Google Scholar 

  58. Catteau L, Reichmann NT, Olson J, Pinho MG, Nizet V, Van Bambeke F, et al. Synergy between ursolic and oleanolic acids from Vitellaria paradoxa leaf extract and β-lactams against methicillin-resistant Staphylococcus aureus: In vitro and in vivo activity and underlying mechanisms. Molecules. 2017;22:2245.

  59. Ilanko P, McDonnell PA, van Vuuren S, Cock IE. Interactive antibacterial profile of Moringa oleifera Lam. extracts and conventional antibiotics against bacterial triggers of some autoimmune inflammatory diseases. South African J Bot. 2019;124:420–35.

    CAS  Google Scholar 

  60. Campana S, Taccetti G, Ravenni N, Masi I, Audino S, Sisi B, et al. Molecular epidemiology of Pseudomonas aeruginosa, Burkholderia cepacia complex and methicillin-resistant Staphylococcus aureus in a cystic fibrosis center. J Cyst Fibros. 2004;3:159–63.

    CAS  PubMed  Google Scholar 

  61. Figueiredo AMS, Ferreira FA. The multifaceted resources and microevolution of the successful human and animal pathogen methicillin-resistant Staphylococcus aureus. Mem Inst Oswaldo Cruz. 2014;109:265–78.

  62. Kabir F, Katayama S, Tanji N, Nakamura S. Antimicrobial effects of chlorogenic acid and related compounds. J Korean Soc Appl Biol Chem. 2014;57:359–65.

    CAS  Google Scholar 

  63. Lin RD, Chin YP, Lee MH. Antimicrobial activity of antibiotics in combination with natural flavonoids against clinical extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae. Phytother Res. 2005;19:612–7.

    CAS  PubMed  Google Scholar 

  64. Catteau L, Zhu L, Van Bambeke F, Quetin-Leclercq J. Natural and hemi-synthetic pentacyclic triterpenes as antimicrobials and resistance modifying agents against Staphylococcus aureus: a review. Phytochem Rev. 2018;17:1129–63.

    CAS  Google Scholar 

  65. Vieira P, Picoli S. Acinetobacter baumannii Multirresistente: Aspectos Clínicos e Epidemiológicos. Rev Bras Ciências da Saúde. 2015;19:151–6.

    Google Scholar 

  66. Tiwari V, Roy R, Tiwari M. Antimicrobial active herbal compounds against Acinetobacter baumannii and other pathogens. Front Microbiol. 2015;6:618.

    PubMed  PubMed Central  Google Scholar 

  67. Isler B, Doi Y, Bonomo RA, Paterson DL. New treatment options against carbapenem-resistant Acinetobacter baumannii infections. Antimicrob Agents Chemother. 2019;63:e01110-18.

    CAS  PubMed  Google Scholar 

  68. Yenjai C, Pitchayawasin S, Bunsupa S, Sangkul S. Phytochemical study of Hymenocardia wallichii Tul. Acta Hort. 2005;677:127–9.

    CAS  Google Scholar 

  69. Chung PY, Chung LY, Navaratnam P. Potential targets by pentacyclic triterpenoids from Callicarpa farinosa against methicillin-resistant and sensitive Staphylococcus aureus. Fitoterapia. 2014;94:48–54.

    CAS  PubMed  Google Scholar 

  70. Kuete V, Wabo GF, Ngameni B, Mbaveng AT, Metuno R, Etoa FX, et al. Antimicrobial activity of the methanolic extract, fractions and compounds from the stem bark of Irvingia gabonensis (Ixonanthaceae). J Ethnopharmacol. 2007;114:54–60.

    CAS  PubMed  Google Scholar 

  71. Li XC, Jacob MR, Pasco DS, ElSohly HN, Nimrod AC, Walker LA, et al. Phenolic compounds from Miconia myriantha inhibiting Candida aspartic proteases. J Nat Prod. 2001;64:1282–5.

    CAS  PubMed  Google Scholar 

  72. Miyasaki Y, Rabenstein JD, Rhea J, Crouch ML, Mocek UM, Kittell PE, et al. Isolation and characterization of antimicrobial compounds in plant extracts against multidrug-resistant Acinetobacter baumannii. PLoS One. 2013;8: e61594.

    CAS  PubMed  PubMed Central  Google Scholar 

  73. Mbaveng AT, Sandjo LP, Tankeo SB, Nidfor AR, Pantaleon A, Nagdjui BT, Kuete V. Antibacterial activity of nineteen selected natural products against multi-drug resistant Gram-negative phenotypes. Springerplus. 2015;4:823.

    PubMed  PubMed Central  Google Scholar 

  74. Augostine CR, Avery SV. Discovery of natural products with antifungal potential through combinatorial synergy. Front Microbiol. 2022;13: 866840.

    PubMed  PubMed Central  Google Scholar 

Download references


The authors are grateful to FUNDECT-MS, CAPES (grant number 308617/2021–5, for D.S.T fellowship), Fundação de Amparo à Pesquisa do Estado do Maranhão (FAPEMA, for T.F.B fellowship), and CPq-PROPP-UFMS for their financial support. Thank is also due to Dr. Joaquim Corsino for the assistance in sampling the plant material, and to Dr. Massuo J. Kato and Dr. Lydia F. Yamaguchi (University of São Paulo, Brazil) for the HPLC-MS analysis. Dr. Geraldo Alves Damasceno Júnior (CGMS Herbarium, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, Brazil) is acknowledged for his assistance in the identification of the plant material.


This study was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES) – grant number 001, and Fundação de Apoio ao Desenvolvimento do Ensino, Ciência e Tecnologia do Estado de Mato Grosso do Sul—FUNDECT-MS – grant number 308/2022.

Author information

Authors and Affiliations



Conceptualization, NCY and ACM; Formal analysis, GSJ, DST, ACM and NCY; Funding acquisition, FRG, ACM and NCY; Investigation, GSJ, AMTF, TFB, BCB, POF, ELS, ACM, NCY; Methodology, DST, AMTF, ACM and NCY; Project administration, ACM and NCY; Resources, DST, AMTF, ACM and NCY; Supervision, NCY and ACM; Validation, GSJ, DST, AMTF, ELS, ACM and NCY; Visualization, FRG, POF, ACM, and NCY; Writing–original draft, ACM and NCY; Writing–review & editing, FRG, POF, ACM and NCY. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Ana Camila Micheletti or Nidia Cristiane Yoshida.

Ethics declarations

Ethics approval and consent to participate

Study on plants comply with relevant institutional, national, and international guidelines and legislation. This work was performed according to the license for research on Brazil’s biodiversity #A5B7329, issued by National System for the Management of Genetic Heritage and Associated Traditional Knowledge (SISGEN/Brazil).

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Additional file 1:

General experimental procedures. Figure 1S.Figure 38S.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

de Jesus, G.S., Silva Trentin, D., Barros, T.F. et al. Medicinal plant Miconia albicans synergizes with ampicillin and ciprofloxacin against multi-drug resistant Acinetobacter baumannii and Staphylococcus aureus. BMC Complement Med Ther 23, 374 (2023).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: