Abstract
The antioxidant activity and total phenolic content of Morinda tinctoria leaves was evaluated. The successively extracted leaves of Morinda tinctoria using various solvents was analyzed for their total phenolic content. The extracts were subjected to column chromatography for the isolation of bioactive molecules. In vitro antioxidant activity was evaluated by employing different assays, including 2,2-diphenyl-1-picrylhydrazyl, nitric oxide scavenging assay and phosphomolybdenum reducing power assay. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging efficacy of hexane extract is significant at higher concentration (500 μg/ml-91.2±0.05%) and the efficacy at lower concentration is more significant for ethyl acetate extract (100 μg/ml - 65.1±0.05%). The total phenolic content was highest in methanol extract (5.30±0.011 μg/mg). Cynarin, a hydroxy cinnamic acid was isolated from chloroform extract; oleuropein, a polyphenolic iridoid was isolated from methanol extract. The results obtained suggeted that Morinda tinctoria leaf extracts possessed antioxidant properties and might offer protection from free radicals. Two compounds, cynarin and oleuropein were reported for the first time from Morinda tinctoria leaves.