Immunomodulatory activity of kaempferol 5-O-β-D-glucopyranoside from Indigofera aspalathoides Vahl ex DC. (Papilionaceae)

The objective of this study was to isolate a new compound from methanol extracts of Indigofera aspalathoides Vahl ex DC. aerial parts and to determine the immunomodulatory activity of the isolated compound. The methanolic extract yielded compounds 1 (0.65 mg), 2 (0.52 mg), and 3 (1.80 g) on chromatography, which was characterized using spectral techniques, namely Fourier transform infrared, H-1 nuclear magnetic resonance, C-13 nuclear magnetic resonance, and mass spectroscopy. Owing to the paucity of compounds 1 and 2, kaempferol 5-O-beta-d-glucopyranoside (compound 3) was evaluated for immunomodulatory activity. Compound 3 was assessed in a neutrophil adhesion and a delayed-type hypersensitivity test, and humoral antibody titers were measured in albino rats. Administration of compound 3 at oral doses of 10, 20, 50, and 100 mg/kg of body weight resulted in a significant (p < 0.05) increase in percent neutrophil adhesion to nylon fibers, a dose-dependent increase in antibody titers, and potentiation of the delayed-type hypersensitivity reaction induced using sheep red blood cells. We concluded that compound 3, methanol extracted from aerial parts of I. aspalathoides Vahl ex DC. possessed significant immunomodulatory activity and therefore has promising therapeutic potential for the prevention of autoimmune diseases.