Ultrasound-assisted polyol extraction of anthocyanins from Leumpua purple sticky rice: Cytotoxicity, antioxidant properties, anti-melanogenic and anti-tyrosinase activities, and stability evaluation

Anthocyanins are bioactive compounds with recognized antioxidant and skin-whitening potential, yet their extraction using polyol-based green solvents remains underexplored. This study develops an ultrasound-assisted extraction (UAE) approach for anthocyanins from Leumpua purple sticky rice and links extraction efficiency with biological activity, safety, and stability to support practical applications. The effects of solvent type and concentration, solid-to-liquid ratio, and extraction time were systematically evaluated and compared with conventional maceration. Under selected conditions (40 % w/v propylene glycol, 1:10 ratio, 5 min), the highest total anthocyanin content (4.41 ± 0.18 mg/g) was obtained, while extraction time was markedly reduced without compromising antioxidant activity. LC–QQQ analysis identified cyanidin-3-O-glucoside and peonidin-3-O-glucoside as the major compounds. The extracts showed low cytotoxicity and significant anti-melanogenic and anti-tyrosinase activities in B16F10 cells, comparable to kojic acid. However, anthocyanins exhibited temperature-dependent degradation, highlighting the need for stabilization strategies. Overall, UAE with polyol solvents offers a rapid and effective extraction approach with promising applicability in cosmetic formulations.