Extraction of flavonoids from durian (Durio zibethinus) fruit rinds and evaluation of their antioxidant, antidiabetic and anticancer properties

Durian (Durio zibethinus) fruit rinds are a promising source of bioactive phytochemicals, but they are currently wasted. This study optimised extraction conditions for flavonoids from durian fruit rinds and evaluated the biological activities of the flavonoid-rich extracts. The highest flavonoid content of 82.17 mg QE g(-1) extract was achieved when performing the extraction at 60 degrees C using 75% ethanol and maceration time of 24 h. The crude ethanolic extract was then fractionated using liquid-liquid extraction to obtain three fractions (CHF, EAF and AQF). Among them, CHF demonstrated the highest amount of flavonoids (271.11 mg QE g(-1) extract) and quercetin (1006.19 mu g g(-1) extract). This fraction also exhibited the highest ferric reducing power (IC50 of 307.88 mu g vitamin C g(-1)), DPPH radical scavenging activity (IC50 of 38.72 mu g mL(-1)), alpha-amylase and alpha-glucosidase inhibitory activity (IC50 of 685.76 mu g mL(-1) and 441.10 mu g mL(-1), respectively) and cytotoxicity against HepG-2 and MCF-7 cells with IC50 values of 490.30 mu g mL(-1) and 343.38 mu g mL(-1) respectively. The current work suggested that durian fruit rinds are a potential source of flavonoids and the CHF could be further used for pharmaceutical applications.