Abstract

IN-VITRO ANTIOXIDANT AND FREE RADICAL SCAVENGING ACTIVITIES OF OCIMUM GRATISSIMUM

Abstract

The present study was carried out to evaluate the antioxidant and free radical scavenging activity of aqueous, ethyl acetate and ethanolic (1:1:1) extract of Ocimum gratissimum (AEEOG) in various systems. DPPH radical, nitric oxide radical, iron chelating ability, ferric reducing antioxidant ability and hydroxyl radical scavenging assays were carried out to evaluate the antioxidant potential of the extract. The antioxidant activity of aqueous, ethyl acetate and ethanolic extract increased in a dose dependent manner. The effect of AEEOG on reducing power increases in a dose dependent manner, indicating some compounds in Ocimum gratissimum is both electron donors and could react with free radicals to convert them into more stable products and to terminate radical chain reactions. The ethyl acetate extract had significantly (P 0.05) higher chelating effect than ethanolic and aqueous extracts. IC50 values for chelating effect of ethanolic, ethyl acetate and aqueous extracts of O. gratissimum were 6.81, 5.51 and 6.34 mg/ml, respectively. In DPPH radical scavenging assay the IC50 value for DPPH scavenging by the ethanolic, ethyl acetate and aqueous extracts of O. gratissimum were 2.47, 1.58 and 5.29 mg/ml, respectively. AEEOG was found to inhibit the nitric oxide radicals generated from sodium nitroprusside, the IC50 values for nitric oxide scavenging ability of ethanolic, ethyl acetate and aqueous extracts of O. gratissimum were 7.51, 13.17 and 21.73 mg/ml, respectively. AEEOG was also found to inhibit the hydroxyl radical generated by the deoxyribose method, the IC50 values for hydroxyl radical effect of ethanolic, ethyl acetate and aqueous extracts of O. gratissimum were 3.98, 6.48 and 8.83 mg/ml, respectively. The total phenolic contents of Ocimum gratissimum were also determined in this study and is found to be 4.00±0.00 mg GAE/g, 10.34±0.47 mg GAE/g and 1.56±0.06 mg GAE/g for aqueous, ethyl acetate and ethanolic respectively. The results obtained in this study indicate that the AEEOG can be a potential source of natural antioxidant.

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