Antioxidant activity of Caryota urens L. (Kithul palm) treacle

Abstract

In Sri Lanka, traditionally, treacle made from Caryota urens L. (Family: Arecaceae) sap is used as a natural sweetener and in Sri Lankan ethanomedicine it is claimed to posses antiageing and antidiabetic potentials. These claims suggest that C. urens treacle may have antioxidant activity. However, this has not been scientifically tested and this study evaluate antixoidant potential of C. urens treacle (n=12) in vitro [using 1,1-diphenyl-2- picryl-hydrazyl (DPPH. ), 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS+ ), ferric reducing antioxidant power (FRAP) and ferrous ion chelating assays with five different treacle concentrations (ranged from 0.2-18.0 mg/l)] and in vivo using rats. Two groups of rats (8/group) were selected and one group was fed daily with standard diet contaning 56% sucrose and the other with standard diet containing 56% treacle for 28 days. Blood was collected from tail, serum seperated on day 1 (post tretment) and antioxidant activity was determined by ABTS+ assay using five serum concentrations (0.06, 1.25, 2.50, 5.00 and 10.0 µl/ml). The in vitro results showed DPPH. radical scavenging activity (0.15 ± 0.01 mmoles Trolox equvilant antioxidant activity (TE)/100 g of treacle), ABTS+ radical scavenging activity (0.57 ± 0.07 mmoles TE/100 g of treacle), ferric reducing antioxidant activity (2.65 ± 0.22 mmoles TE /100 g of treacle) and ferrous ion chelating activity (IC50; 19.6 ± 3.9 mg/ml). In vivo results showed significant increase in serum antioxidant capacity of treacle fed group compared to control (IC50; control vs treatment: 5.74 ± 0.13 vs 4.63 ± 0.18 µl/ml and Trolox equivalant antioxidant concentration; control vs treatment: 2.96 ± 0.06 vs 3.70± 0.13 mM TE). This is the first report of both in vitro and in vivo antioxidant capacity of any treacle and it is concluded that Sri Lankan C. urens treacle has moderate antioxidant activity both in vitro and in vivo and has the potential to be used as health promoting natural sweetener