Effect of chondrillasterol on P. aeruginosa biofilm formation. P. aeruginosa (1.6 × 106 cfu/mL) was incubated with different concentrations of the pure compound for 72 h. at 37 °C and the resulting biofilm mass was stained using crystal violet staining. The dye was extracted using ethanol and quantified spectrophotometrically at 590 nm. The absorbance values of crystal violet are directly proportional to the amount of biofilm that had formed. The error bars indicate the standard deviation from mean (n = 4). Dunnet multiple comparison test was used to compare columns using GraphPad Prism (GraphPad Software Inc., San Diego, California, USA) version 5.03. The asterisks (*) indicate statistically significant differences with the positive control (0.0) which represented cells only without extract * < 0.05 *** < 0.0001. TSB is tryptic soy broth.