Ultrasonic-assisted extraction (UAE) of Javanese turmeric rhizomes using natural deep eutectic solvents (NADES): Screening, optimization, and in vitro cytotoxicity evaluation

Javanese turmeric (Curcuma xanthorrhiza Roxb.) is known for its diverse pharmacological activities due to its rich phytoconstituents, including curcuminoids and xanthorrhizol. Typically, these compounds are extracted using organic solvents, which pose health and environmental risks. Therefore, safer and more environmentally friendly green extraction methods are being developed. This study investigated the effect of ultrasound-assisted extraction (UAE) combined with natural deep eutectic solvents (NADES) based on choline chloride and organic acids (lactic, malic, and citric acid) to find the best combination for extracting curcuminoids and xanthorrhizol from Javanese turmeric. Results showed that UAE using choline chloride and malic acid (1:1) (ChCl-MA) yielded the best results. The Box-Behnken Design optimized water addition, solvent-to-powder ratio, and extraction time, with optimal conditions being 25 % water addition, a 20 mL/g ratio, and a 15-minute extraction time. This method yielded 4.58 mg/g of curcuminoids and 12.93 mg/g of xanthorrhizol. Furthermore, the ChCl-MA NADES with UAE extraction showed more cytoselective activity towards the HeLa cancer cell line compared to the non-cancer HaCaT cell line. In contrast, traditional ethanol extraction was non-selective, as indicated by similar cell viability reductions in both HeLa and HaCaT cells at 6.25 ppm. Collectively, this study is the first to report the optimal NADES combination with UAE, based on salts and organic acids, for the extraction of Javanese turmeric rhizomes with selective cytotoxic effects against cancer cells. These findings may contribute to the development of novel, naturally derived anticancer agents using green extraction techniques.