Enzyme inhibiting, antibacterial and antioxidant activities of peel, pulp and seed extracts from dau Ha Chau (Baccaurea ramiflora Lour.) fruit of Vietnam

Abstract

Dau Ha Chau (DHC) was produced by selecting and growing native kinds of Baccaurea ramiflora Lour. in Vietnam, where the fruit is utilized for fresh eating not only due to its distinctive sour-sweet flavor, but also because of its vitamins and minerals for the body. With the aim to enhance the value of this fruit, the peel, pulp, and seed extracts were determined antioxidant, antibacterial and antidiabetic activities. The filtrates from ethanol extract of peel and seed powders and fruit juice from squeezing pulp were evaporated at 58°C to create the extracts. The six methods of TAC, DPPH, ABTS•+, RP, FRAP, and NO• (antioxidant activities), four bacterial strains and two enzymes (associated with type 2 diabetes mellitus) were evaluated. The results showed that the extract of DHC peel exhibited the highest antioxidant activity (EC50 value from the six methods), antibacterial activity (MIC value), enzyme inhibiting activity (IC50 value), total phenolics content and total flavonoids content, at 643.81 µg/mL, 787.42 µg/mL, 651.10 µg/mL, 718.22 µg/mL, 270.38 µg/mL, 662.44 µg/mL, 16 < MIC ≤ 32 mg/mL (against Propionibacterium acnes, Escherichia coli and Bacillus cereus), 32 < MIC ≤ 64 mg/mL (against Staphylococcus aureus), 2780.91 µg/mL (against α-amylase), 541.24 µg/mL (against α-glucosidase), 119.43 mg GAE/g and 207.17 mg QE/g, respectively, whereas the opposite was true for extract of DHC seed. DHC pulp extract came second in all analytical methods. Pearson correlation coefficients with r value (0.63-0.99) showed a reasonably strong relationship between total phenolics and flavonoids contents, and antioxidant and enzyme inhibiting activities. This is the first report on the antioxidant, antibacterial and antidiabetic activities of DHC Ha Chau fruit extracts, which could be developed for medicinal, pharmaceutical, food preservative purposes, or industrial foods in the future.