Comparative Studies on in Vitro Free Radical Scavenging Activity of Aqueous, Ethanol, Ethylacetate and N-Hexane Extracts of Leaves of Datura stramonium and Ocimum gratissimum

Abstract

The in vitro Free Radical Scavenging Activity of aqueous, ethanol, ethylacetate and n-hexane extracts of leaves of Datura stramonium and Ocimum gratissimum were investigated. Due to the fact that Free radicals are implicated in many diseases including diabetes mellitus, arthritis, cancer, ageing. etc. In the treatment of these diseases, antioxidant therapy has gained utmost importance. The phytochemical analysis was carried out by standard methods and the antioxidant activity of the various extracts were measured on the basis of the free radical scavenging activity of the extract on stable 1, 1-diphenyl 2-picrylhyorazyl (DPPH) at varying concentrations of the plant extracts (20, 40, 60, 80 and 100 µg/ml) and absorbance was measured at 517nm using UV-Vis spectrophotometer. The results indicated that alkaloids, flavonoids, terpenoids, steroids and tannins were present in D. stramonium ethanol leaf extract while alkaloids, flavonoids, terpenoids and steroids were present in O. gratissimum n-Hexane leaf extract. The percentage inhibition of the solvent extracts at 100 μg/ml - aqueous (30.77 %), ethanol (74.90 %), ethylacetate (49.94 %) and n-hexane (69.90 %) for D. stramonium while for O. gratissimum - aqueous (45.84 %), ethanol (49.47 %), ethylacetate (63.94 %) and n-hexane (91.14 %). Of all the extracts, n-hexane leave extract of O. gratissimum exhibited the highest free radical scavenging activity with IC50 0.21 μg/ml compared to ethanol leave extracts of D. stramonium with IC50 0.29 μg/ml. This study revealed that n-hexane leaf extract of Ocimum gratissimum had a more potent antioxidant activity compared to the ethanol leaf extract of D. stramonium which had moderate antioxidant activity. Both plants extracts had no significant difference when compared with ascorbic acid standard (0.19 µg/ml) at (P≤.05). The phytochemical profile of the plants might be responsible for their high antioxidant activity, thus justifying wide use of O. gratissimum in diet which could provide a source of high dietary antioxidants and D. stramonium in ethno-botanical applications.