Yak-Kong Soybean () Fermented by a Novel Inhibits the Oxidative Stress-Induced Monocyte-Endothelial Cell Adhesion.

Yak-Kong (YK), a small black soybean () in Korea, contained higher concentrations of antioxidants than ordinary black soybean or yellow soybean in our previous study. We prepared the fermented YK extract by using a novel lactic acid bacterium, AOA2017 (AOA2017) isolated from , and found that the antioxidant ability was enhanced after fermentation. In order to investigate the cause of the enhanced antioxidant ability in the fermented YK extract, we conducted a phenolic composition analysis. The results show that proanthocyanidin decreased and phenolic acids increased with a statistical significance after fermentation. Among the phenolic acids, p-coumaric acid was newly produced at about 11.7 mg/100 g, which did not exist before the fermentation. Further, the fermented YK extract with increased p-coumaric acid significantly inhibited the lipopolysaccharide-induced THP-1 monocyte-endothelial cell adhesion compared to the unfermented YK extract. The fermented YK extract also suppressed the protein expression levels of vascular cell adhesion molecule (VCAM)-1 in human umbilical vein endothelial cells (HUVECs). Together with the previous studies, our results suggest that the extract of YK fermented by AOA2017 has potential to be a new functional food material with its enhanced bioactive compounds which may help to prevent atherosclerosis caused by oxidative stress.