Anti-Inflammatory Effects and Their Correlation with Microbial Community of Shindari, a Traditional Jeju Beverage

Abstract

In this study, we investigated the microbial community and its correlation with anti-inflammatory effects during the fermentation procedure of shindari. Since shindari is traditionally manufactured through a fermentation process of 3–4 days in summer or 5–6 days in winter, the shindari materials applied in this study were fermented for 1, 3, and 5 days, respectively. Microbial community structure in the shindari manufacturing process was analyzed by Illumina MiSeq sequencing. Results revealed different fermentation time had different influences on the community structure and microbial diversity in the shindari process. Ultimately, we found that pathogenic bacteria such as Enterococcus durans (9.3%) and Enterobacter asburiae (4.5%) dominate the shindari fermented for 1 day, while samples with a fermentation period of more than 3 days occupied lactic acid bacteria such as Pediococcus sp. (97.1%). In addition, to study the relationship between fermentation period and anti-inflammatory effect in the shindari manufacturing process, we applied RAW264.7 cells, a classic cell model for inflammation studies. First, we prepared an ethyl acetate extract of shindari fermented for 1 (S1), 3 (S3), or 5 days (S5), and then it was confirmed that all of these extracts inhibited the nitric oxide (NO) production in a concentration-dependent manner. In addition, these inhibitory effects were correlated with the suppressive effect of shindari extracts against overexpression of inducible nitric oxide synthase (iNOS). Furthermore, S3 and S5 also inhibited the production of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6. Overall, the anti-inflammatory effect of S3 was suggested to be mediated through the negative regulation of mitogen-activated protein kinase signaling (MAPKs) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways.