ANTIOXIDANT ACTIVITY OF METHANOLIC EXTRACT OFDUNALIELLA BARDWIL

摘要

An ideal antioxidant should be readily absorbed and quench free radicals, and chelate redox metals at physiologically relevant levels. The present study is focussed on the antioxidant and free radical scavenging properties of Dunaliella bardawil. Theobjective of the present study is to evaluate the antioxidant activity of D. bardawil using seven methods viz., DPPH radical quenching method, H202 scavenging assay, No radical scavenging assay, reducing capacity assay and FTC method, TBA method and Total phenolic content. Ascorbic acid, oc-Tocopherol and vitamin C were used as standards. The methanolic extract of D.bardawil showed strong DPPH radical scavenging activity of 86.72±0.33% value with IC50 value of 2.25±0.11 ug/mL and in H202 scavenging activity of 94.24+1.33% with IC^ value of 3.88±0.67 ug/mL, No radical scavenging activity with 63.55±0.52% with IC^ value of 3.22±0.28 ug/mL. The Dunaliella extract with concentrations higher than 4 mg/mL showed a higher reducing power than alpha-tocopherol and BHA. A volume of 800 uL of 2.5% linoleic acid in 99.8% ethanol in a total volume of 20mL, was found to produce the highest absorbance readings and both showing a slightly reduced absorbance after the 8th day. Maximum generation of lipid hydroperoxides was achieved by incubation at 37°C (body temperature). In Green phase the contents of phenolic compounds (mg/g) in aqueous extracts of D. bardawil was found 482.18±12.30 mg GAE/g dry wt and in red phase 525±30.19 mg GAE/g dry wt. Dunaliella showed relatively fair antioxidant potential according to FTC and TBA method but comparatively low DPPH radical scavenging activity. From all these observations it can be concluded that, the algal extracts with high level of polyphenolic compounds and P carotene in Dunaliella show excellent antioxidant activity in vitro systems.