Fig. 2

Effects of crude leaf extracts and purified fractions of V. trifolia on TNF-α and IL-1β production by human U937 macrophages. Fold change of TNF-α (a, c, e, g) and IL-1β (b, d, f, h) production relative to control in the supernatant of human U937 macrophages measured by ELISA. Cells were pre-incubated for 6 h with the appropriate extracts or fractions (10 μg/mL in (e, f); 2 μg/mL in (g, h)), followed by LPS stimulation. Fractions in (e, f) were purified from maceration ethanol crude extract, while A1 fraction was purified from the dichloromethane fraction in (e, f). Cytokine production by cells not treated with any extract or fraction (ie. none) was taken as 1. Dexamethasone (Dex) at 64.4 ng/mL was used as a positive control. The data are presented as mean fold change ± SD of three independent experiments performed in duplicates. *p < 0.05