Antioxidant Activity of Caryota urens L. (Kithul) Sap

In Sri Lanka young inflorescence of Caryota urens L (Family: Arecaceae) is tapped for sweet sap that is then used for preparation of fermented beverage and sweeteners. In folkloric, these products are claimed to have health benefits. However, as yet biological activities of C. urens sap have not been scientifically investigated. Recent scientific investigations reported the nutritional value of C. urens sap and its potential as a healthy natural beverage. In this study, antioxidant properties of C. urens sap were studied as a major biological function that may contribute to the claimed health benefits. Antioxidant activity of C. urens sap collected from three major tapping locations of the country (Kotmale, Gampola and Matara) was estimated using1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS + ), Ferric Reducing Antioxidant Power (FRAP) and metal ion chelating assays. From each location 15 samples were used. Radical scavenging activity and FRAP value were calculated as Trolox Equivalent Antioxidant Concentration (TEAC) per 100 g of sap and expressed as mmol Trolox Equivalent (TE). DPPH radical scavenging activities were 0.74±0.05, 0.58±0.07 and 1.15±0.05 mmol TE/100 g and ABTS + radical scavenging activities were 1.44±0.10, 1.22±0.14 and 1.64±0.11 mmol TE/100 g for Kotmale, Gampola and Matara, respectively. FRAP values were 2.54±0.25, 2.22±0.34 and 2.92±0.28 mmol TE/100 g and metal ion chelating activity as Inhibitory Concentration 50% (IC50) was 6.02±0.31, 3.37±0.40 and 3.73±0.33 mg/ml for Kotmale, Gampola and Matara, respectively. This study shows, for the first time, antioxidant activity of C. urens sap, as determined by free radical scavenging activity, electron donating reducing power and metal ion chelating capacity. The results provide some scientific information for traditionally claimed health benefits of C. urens.