Phenolic compounds and in vitro biological activities of nonanthocyanin fractions from mulberry fruits harvested at different maturity stages

Mulberry fruits contain substances involved in physiological activities beneficial to human health. To explore potential utilization of mulberry fruits as functional foods, functional compounds and in vitro biological activities of their extracts were determined at different maturity stages. As maturity progressed, nonanthocyanin fraction (NAF) decreased, while anthocyanin fraction (AF) increased. Main phenolic acid contained in the NAF was chlorogenic acid, which decreased during ripening. Main flavonols present in the NAF were rutin, isoquercetin, and morin, which also decreased during ripening. The NAF and AF exhibited anti-inflammatory properties by lowering nitric oxide production in Raw264.7 cells. The NAF of immature mulberry fruits promoted hexokinase activity in HepG2 cells and inhibited alpha-glucosidase, indicating its possible hypoglycemic effect. It is suggested that immature mulberry fruits that are rich in non-anthocyanin phenolics might be a potential functional food source.