ABSTRACT
Antioxidant activity and total phenolic content of tamarind seed coat extracts (TSCEs) were compared between the two extracts using boiling-water (TSCE-W) and 70% ethanol (TSCE-E) for extraction. TSCE-W, consisting of the highest phenolic content, possessed 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and anti-lipid peroxidation activities much higher than TSCE-E and Trolox. Additionally, both TSCEs also exhibited superoxide anion and hydrogen peroxide scavenging activities higher than Trolox and BHA. Anti-lipid peroxidation and cytotoxicity of TSCE-W were also studied in human foreskin fibroblast CCD-1064Sk cells. Cytotoxic effect was not observed when exposed to TSCE-W up to 1 mg/mL for 12-48 h. However, TSCE-W significantly attenuated lipid peroxidation in H2O2-damaged cells. HPLC analysis showed the presence of (+)-catechin, (-)-epicatechin, and procyanidin B2 in TSCE-W, which could be responsible for antioxidant and anti-lipid peroxidation activities. The results suggest that an inexpensive and simple boiling-water extraction of TSCE-W may provide a valuable natural antioxidant source having anti-lipid peroxidation for health food additives, nutraceuticals as well as cosmeceuticals.