In Vitro Antioxidant Activity of Bark Extracts of Rhizophora mucronata

The present study was conducted to evaluate the antioxidant activity of medicinal plant Rhizophora mucronata (R. mucronata). Shade dried stem bark of R. mucronata was powdered and extracted with 95% ethanol and water by cold extraction method. The total phenolic and flavonoid contents of water and ethanol extract of air dried stem bark was estimated by using spectrometric method. Antioxidant activity of R. mucronata was determined by using different methods namely DPPH radical scavenging assay, ferric reducing assay, nitric oxide radical scavenging assay, superoxide radical scavenging assay and ABTS radical scavenging assay, and its IC^sub 50^ values were found to be 110.85 μg/ml, 193.47 μg/ml, 109.06 μg/ml, 88.69 μg/ml and 12.56 μg/ml for aqueous extract and 59.63 μ, 242.71 μ, 103.21 μ, 84.95 μ and 4.21 μ, respectively. The extracts exhibited marked dose dependent in vitro antioxidant activity. Secondary metabolite isolation and characterization and in vivo evaluation of aqueous and ethanolic extracts were under progress.