Immunomodulating effects of Hypoxis hemerocallidea, Sutherlandia frutescens and standard compounds found in these plants were determined. Neither of the extracts, nor the standard compounds were cytotoxic to THP-1 and U937 macrophages. Antioxidant activity of H. hemerocallidea was equivalent to 0.2 mg/mL Trolox. Canavanine showed antioxidant activity comparable to that of curcumin (positive control). Curcumin (9.2 μg/mL) and beta-sitosterol (12.5 μg/mL) reduced IL-1β and IL-8 production significantly (p < 0.05) and decreased the production of TNF-α. Beta-sitosterol (25 μg/mL) and pinitol (50 μg/mL) significantly (p<0.01) decreased extracellular PGE2 levels in U937 macrophages by 12 % and 14 %, respectively. From the current results it would appear that the standard compounds present in the plants are far more effective in modulating the immune system than the extracts.Colegio de Farmacéuticos de la Provincia de Buenos Aire
