Fig. 1

Effects of V. trifolia crude leaf extracts on TNF-α and IL-1β production by human U937 macrophages. a, b Absolute production of TNF-α (a) and (b) IL-1β by human U937 cells in the presence or absence of PMA, LPS and dexamethasone. c-f Fold change of (c, e) TNF-α and (d, f) IL-1β production relative to control in the supernatant of human U937 macrophages. Cells were pre-incubated for 6 h with 100 μg/mL (c, d) or 2 μg/mL (e, f) of the appropriate crude leaf extract, followed by LPS stimulation. Sox, Soxhlet; Ult, ultrasonication; Mac, maceration; W, water; E, ethanol; M, methanol; D, dichloromethane; H, hexane. Cytokine production by cells not treated with any extract (ie. none) was taken as 1. Dexamethasone (Dex) at 64.4 ng/mL was used as positive control. The data are presented as mean fold change ± SD of three independent experiments performed in duplicates. *p < 0.05