Analgesic, antiinflammatory and hypoglycemic effects of Sutherlandia frutescens R. BR. (variety Incana E. MEY.) [Fabaceae] shoot aqueous extract.

Previous studies on the pharmacology of South African medicinal plants in our laboratories and elsewhere have shown that some plants possess therapeutic attributes. One such ethnomedically useful plant is Sutherlandia frutescens R. BR. (family: Fabaceae). S. frutescens is widely used in South African traditional medicine for the management and/or control of a plethora of human ailments. In order to scientifically appraise some of the ethnomedical uses of S. frutescens, the present study was undertaken to investigate the analgesic, antiinflammatory and antidiabetic properties of the plant's shoot aqueous extract in experimental animal models. The analgesic effect of the herb's shoot extract was evaluated using the hot-plate and acetic acid test models of pain in mice, while the antiinflammatory and hypoglycemic effects of the plant's shoot aqueous extract were investigated in rats, using fresh egg albumin-induced pedal (paw) edema, and streptozotocin (STZ)-induced diabetes mellitus. Diclofenac (100 mg/kg) and chlorpropamide (250 mg/kg) were used, respectively, as reference drugs for comparison. S. frutescens shoot aqueous extract (50-800 mg/kg i.p.) produced significant (p < 0.05-0.001) analgesic effects against thermally- and chemically-induced nociceptive pain stimuli in mice. The plant extract (50-800 mg/kg p.o. or i.p.) also significantly (p < 0.05-0.001) inhibited fresh egg albumin-induced acute inflammation and caused significant (p < 0.05-0.001) hypoglycemia in rats. The various chemical constituents and secondary metabolites of the herb are speculated to account for the observed analgesic, antiinflammatory and hypoglycemic effects of the plant. The results of this experimental animal study suggest that S. frutescens shoot aqueous extract possesses analgesic, antiinflammatory, and hypoglycemic properties, and thus lend pharmacological credence to the suggested folkloric uses of the herb in the management and/or control of painful, arthritic and other inflammatory conditions, as well as for adult-onset, type-2 diabetes mellitus in some communities of South Africa.