Antioxidant, antimicrobial, and anti-obesity activity of lactic acid bacteria- bioconversioned black raspberry (Rubus Coreanus Miquel) extract

This study investigated the antioxidant, antimicrobial, and anti-obesity activity of black raspberry (Rubus coreanus Miquel) extract (BRE) following bioconversion by lactic acid bacteria (LAB). Fermentation of BRE was conducted using Lactobacillus rhamnosus GG, L. plantarum, and Pediococcus acidilactici HW01. After bioconversion by LAB, the total phenolic, flavonoids, and anthocyanin contents were increased by 19%, 8%, and 29%, respectively. The antioxidant activities measured by DPPH and ABTS radical scavenging activities were increased to 20% and 22%, respectively. The antibacterial activities against pathogenic bacteria were also enhanced compared to the control. To verify the anti-obesity activity, the expression of mRNA levels for PPARγ, C/EBPα, aP2, and LPL were measured using RT-PCR in 3T3-L1 cells and along to confirm the inhibition of lipids accumulation by the Oil red O staining test. The bioconversion of BRE by L. plantarum showed the highest antibacterial and anti-obesity activities. A total of 31 volatile compounds, including 3 acids, 12 alcohols, 4 aldehydes, 2 esters, 3 ketones, and 7 terpenes were analysed by HS-SPME-GC/MS. An increase of 30% was observed in the total volatile contents following bioconversion by L. plantarum.