Improving bioactivities of Momordica charantia broth through fermentation using mixed cultures of Lactobacillus plantarum, Gluconacetobacter sp. and Saccharomyces cerevisiae

Momordica charantia [MC] is consumed as a vegetable and traditional medicine due to the presence of various bioactive compounds including charantin and coumarin which have anti-diabetic and anti-gout effects respectively. In this study, we investigated the effect of MC fermentation on its bioactivities. Anaerobic fermentation of Lactobacillus plantarum using MC extract with 10% soymilk at 30 °C increased charantin content to 13.46 ppm. Furthermore, α-amylase inhibition activity was increased to 64.75% and DPPH free radical scavenging ability to 47.14%, a 13.02%, and 11.68% increase, respectively. MC broth fermentation by Gluconacetobacter increased xanthine oxidase inhibition (XOI) activity by 30.77% on the 18th day of fermentation. Co-culture of Gluconacetobacter and S. cerevisiae increased XOI activity by 34.28% on the 12th day of fermentation. When compared to pure cultures, the multi-strain fermentation involving Gluconacetobacter, S. cerevisiae and L. plantarum increased XOI activity by 44.72% on the 6th day of fermentation and reduced fermentation time by 12 days. The results show that L. plantarum has an additive effect on XOI activity, whereas, S. cerevisiae works indirectly by producing alcohol which serves as a nutrient for Gluconacetobacter.