Composition and content of total phenolics and flavonoids, and antioxidant activity of Trigonella isthmocarpa

The aqueous methanolic extracts obtained from aerial parts and seeds of T. isthmocarpa Boiss. & Bal. from Turkey were analyzed by reversed-phase HPLC for their phenolic acid and flavonoid composition. Total phenolic content was determined using the Folin-Ciocalteu assay, while total flavonoid content was measured spectrometrically with AlCl3 assay. Primary antioxidant activity in terms of free radical scavenging activities of both extracts was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The highest total flavonoid and total phenolic content was determined in the extract of aerial parts (830.8 mg/100 g and 877.9 mg gallic acid equivalent/100 g, respectively). The extracts of aerial parts and seeds had the high antioxidant activity (87.2 % and 78.2%, respectively). Gallic acid, caffeic acid, luteolin, apigenin and kaempferol were detected as phenolic compounds in both extracts by HPLC methods. In addition, an isoflavone, formononetin was determined in the extract from aerial parts of the plant. The present results suggest that T. isthmocarpa have shown potential a source of natural antioxidants.