Antioxidant and platelet aggregation inhibitor activities of black tea (Camellia sinensis L.) extract and fractions

The dried leaves of Camellia sinensis L., is a popular beverage consumed worldwide and contains bioactive compounds. The research was carried out to evaluate antioxidant and antiaggregation activities of black tea extract and fractions namely hexane, ethyl acetate, butanol and water fraction. Antioxidant activity of extract and four fractions of black tea were evaluated by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging method and total phenolic compound were determined. Platelet aggregation was determined using whole blood of hyperaggregation individual and analyzed by aggregometer after induction by epinephrine (EPN). The results showed that black tea extract, exhibited highest DPPH free radical scavenging acitivity with IC₅₀ = 5.405 μg/mL among black tea fractions, but still lower comparing to (−)-epigallocatechin-3-gallate (EGCG) with IC₅₀ = 0.505 μg/mL. The highest total phenolic compounds was ethyl acetate fraction (499.07 EGCG μg/mg) and the lowest was water fraction (149.77 EGCG μg/mg). Extract and fractions of black tea were capable in lowering platelet aggregation both at high and low concentrations of EPN (300 and 75 μM) inducer compared to untreated blood. Ethyl acetate, water fractions and extract of black tea showed similar platelet antiaggregation compared with aspirin as positive control.