Green extraction of polysaccharides from Camellia oleifera fruit shell using tailor-made deep eutectic solvents

Camellia oleifera fruit shells are often discarded as byproducts in the C. oleifera industry. There is a general interest in isolating high-value natural products to valorize those fruit shells with green, rapid, and effective extraction methods. This study employed 43 combinations of deep eutectic solvents (DESs) to extract polysaccharides from C. oleifera fruit shells. Two choline chloride-based DESs and a ternary DES with propionic acid and 1,3-butanediol as hydrogen bond donors exhibited relatively high extraction efficiency. The polysaccharide yield reached 15.03 ± 0.35 % under optimized extraction time (55 min), extraction temperature (70 °C), and DES water content (33.33 %). The physicochemical composition and preliminary structure of obtained polysaccharides were characterized. Additionally, DESs-extracted polysaccharides exhibited higher in vitro antioxidant activities and hypoglycemic effects compared to water-extracted polysaccharides. These findings suggested that the optimized DES-assisted extraction method could be a potential approach for polysaccharides extraction from C. oleifera.