Microbial fermentation provides a valorization strategy, through biotransformation, to convert plant-derived raw materials into health-promoting agents. In this study, we have investigated the antioxidative activity of Abelmoschus manihot fermented with various Bacillaceae strains from specific environments and demonstrated the anti-inflammatory effects of Bacillus licheniformis CP6 fermented A. manihot extract (FAME) in lipopolysaccharide (LPS)-stimulated Raw264.7 macrophages. Of 1500 bacteria isolated from various specific environments, 47 extracellular protease- and amylase-producing strains with qualified presumption safety status, belonging to the family Bacillaceae, were selected for A. manihot fermentation. Among them, strain CP6, a halophilic bacterium isolated from Tongyeong seawater in Korea and identified as B. licheniformis, showed the highest antioxidant activity. In particular, FAME exerted anti-inflammatory effects on LPS-stimulated Raw264.7 macrophages. Consequently, FAME had a potent inhibitory effect on nitric oxide (NO) production in LPS-stimulated macrophages, without cytotoxicity. Moreover, FAME downregulated LPS-induced pro-inflammatory mediator and enzyme levels in LPS-induced Raw264.7 cells, including IL-1β, IL-6, TNF-α, iNOS, and COX-2, compared to levels when cells were incubated in A. manihot extract (IAME). Further detailed characterization indicated that FAME suppresses inflammation by blocking NF-κB via IKK phosphorylation inhibition and IκB-α degradation and by downregulating NO production, and inflammatory mediators also decreased NF-κB translocation. Furthermore, FAME inhibited LPS-stimulated activation of MAPKs, including ERK1/2, JNK, and p38, compared to that with either IAME. Therefore, we suggest that FAME could be used for inflammation-related disorders.
Keywords: Abelmoschus manihot; Bacillus licheniformis CP6; MAPK; NF-κB; anti-inflammation; antioxidation; fermentation.