Effects of solvent conditions on the antioxidant activities of biologically active compounds extracted from tamarind (Tamarindus indica L.) seed
Nguyen Van Toan, Phan Thanh Nguyet Que
This study researched on the effect of different extraction solvents on the antioxidant activities of biologically active compounds which were extracted from tamarind seeds. Ethanol, methanol solvents with three solvent-to-water proportions of 30%, 40%, 50%; and water were used for extracting at three temperature conditions (300C, 400C and 500C). The Folin-Ciocalteu’s method, DPPH radical scavenging method were used for determination antioxidant activity, when ferric reducing antioxidant power assay were used for assessment of reducing ability. The highest TPC value was obtained by using methanol 40% at 400C (3.62 ± 0.12 mg GAE/ g TSE powder). The percentages of antioxidant activity inhibition of TSE powder extracts in DPPH radical scavenging method were also highest when using methanol 40% at the temperature of 300C (60.71 ± 0.05%). In FRAP assay, reducing ability of different solvents were increased when increasing solvent concentrations (from 30% to 50%) and thermal conditions (from room temperature to 400C), in which ethanol 50% showed the highest value (2.09 ± 0.02 mM TE/ g TSE powder). As a result, methanol 40% was suitable for the extraction of biologically active compounds from tamarind seeds. However, methanol needed to be considered for food safety.