Preliminary study of the antioxidant properties of flowers and roots of Pyrostegia venusta (Ker Gawl) Miers

BACKGROUND Free radical stress leads to tissue injury and can eventually to arthritis, atherosclerosis, diabetes mellitus, neurodegenerative diseases and carcinogenesis. Several studies are ongoing worldwide to find natural antioxidants of plant origin. We assessed the in-vitro antioxidant activities and screened the phytochemical constituents of methanolic extracts of Pyrostegia venusta (Ker Gawl) Miers. METHODS We evaluated the antioxidant potential and phytochemical constituents of P. venusta using 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2, 2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays. Gas chromatography-mass spectroscopy (GC-MS) studies were also undertaken to assess the phytochemical composition of the flower extracts. RESULTS Phytochemical analyses revealed the presence of terpenoids, alkaloids, tannins, steroids, and saponins. The reducing ability of both extracts was in the range (in μm Fe(II)/g) of 112.49-3046.98 compared with butylated hydroxytoluene (BHT; 63.56 ± 2.62), catechin (972.02 ± 0.72 μm) and quercetin 3208.27 ± 31.29. A significant inhibitory effect of extracts of flowers (IC50 = 0.018 ± 0.69 mg/ml) and roots (IC50 = 0.026 ± 0.94 mg/ml) on ABTS free radicals was detected. The antioxidant activity of the extracts of flowers (95%) and roots (94%) on DPPH radicals was comparable with that of ascorbic acid (98.9%) and BHT (97.6%). GC-MS study revealed the presence of myoinositol, hexadecanoic acid, linoleic acid, palmitic acid and oleic acid in the flower extracts. CONCLUSION These data suggest that P. venusta is a natural source of antioxidants. The extracts of flowers and roots of P. venusta contain significant amounts of phytochemicals with antioxidative properties and could serve as inhibitors or scavengers of free radicals. P. venusta could be exploited as a potential source for plant-based pharmaceutical products. These results could form a sound basis for further investigation in the potential discovery of new natural bioactive compounds.