Extraction of flavonoids from black mulberry wine residues and their antioxidant and anticancer activity in vitro
Jian Ma, Peng Li, Yanhong Ma, Liya Liang, Feihong Jia, Yu Wang, Lijun Yu, Wuyang Huang
Abstract
Enhancing the valorization of fruit processing by-products is pivotal for advancing the industry. Black mulberry wine residues, a by-product, contains some bioactive compounds, yet its antioxidant and anticancer potentials remain unverified. In this study, ultrasound-assisted enzymatic extraction was optimized by response surface methodology to obtain the flavonoids extracts from black mulberry wine residues, whose antioxidant capacity and anti-cancer activity in vitro was investigated. The results showed that under the optimal extraction conditions (enzyme ratio at pectinase:cellulose = 2:1, mixed enzyme concentration 0.31 mg/mL, enzymatic hydrolysis temperature 55.35 °C, enzymatic hydrolysis time 79.03 min, and ultrasonic time 22.71 min), the extracts from black mulberry wine residues (BMWR-E) reached 5.672 mg/g. At a concentration of 1.2 mg/mL, BMWR-E exhibited strong DPPH and hydroxyl radical scavenging activities. At a concentration of 2.5 mg/mL, BMWR-E showed a strong superoxide anion radical scavenging capacity, with no significant distinction compared to the positive control group (Vitamin C) ( p > 0.05). Cell viability assay results showed that BMWR-E was non-toxic to normal BRL-3A cells when applied at concentrations of 0.1 to 0.3 mg/mL for an incubation period of 24 hours, but BMWR-E exhibited the ability to inhibit the proliferation of HepG2 cells. At concentrations of 0.2 mg/mL and above, BMWR-E could induce late apoptosis of HepG2 cells by increasing the protein expression levels of Bax, caspase-3, and caspase-12, reducing the protein expression levels of Bcl-2, inducing cell cycle arrest at G0/G1 phase, thereby inhibiting the proliferation of HepG2 cells. The bioactive properties make BMWR-E possess potential in developing new antioxidants and anti-cancer agents, which would significantly enhance the economic worth of agricultural by-products in product processing. This research can improve the utilization rate of agricultural product processing by-products and protect the environment.