Potential anti-obesity effect of fermented adzuki beans and their untargeted metabolomics using UHPLC-QTOF-MS

Nowadays, obesity is an ultimate public health problem worldwide. However, medical and surgical treatment methods for alleviating obesity can cause multiple adverse side effects. Therefore, in the present study, we evaluated the potential anti-obesity effect of five seeds buckwheat, pea, soybean, red kidney bean, and adzuki beans cultivated in South Korea. Anti-obesity screening of seeds showed adzuki beans with the highest lipase (77.2%) and alpha-amylase (60.5%) inhibitory activity. Later, adzuki beans were fermented using different lactic acid bacteria (LABs). After fermentation, Pediococcus acidilactici fermented adzuki beans displayed significant anti-obesity ability, showing the half maximal inhibitory concentration (IC50) of lipase (from 1.908 to 0.839 mg/ mL) and alpha-amylase (from 0.6873 to 0.379 mg/mL) decreased markedly compared to raw adzuki beans. UHPLC-QTOF-MS was applied to investigate metabolites and their metabolic responses during fermentation. The omics results identified 121 differentially expressed metabolites belonging to organic acids, polyphenols, amino acids and alkaloids. Furthermore, pathway enrichment revealed that P. acidilactici fermentation mainly affected fatty acid, biotin metabolism and alkaloid biosynthesis pathway, which could contribute to the promoting anti-obesity properties of adzuki beans. The metabolomics methods provide novel insights into the metabolic pathway regulation of adzuki beans in response to improving anti-obesity ability after fermentation. These findings suggest that fermenting adzuki beans with P. acidilactici might be a promising method for developing functional foods with anti-obesity properties.