15E-11

3-Hydroxy-3-methylglutaryl-CoA reductase (HMGR) is the rate-limiting enzyme in the biosynthesis of cholesterol in mammals. Some microbial metabolites have been found to be HMGR inhibitors. Korean soybean paste is a unique food fermented by many microorganisms. Therefore, in this study, inhibitors of HMGR in Korean soybean paste were screened and identified.

Vero cells were used for the selection of samples showing potent inhibitory activity towards HMGR and an enzymatic method using the catalytic domain of Syrian hamster HMGR were employed for the screening of HMGR inhibitors.

Preparative TLC was used to find out the different activities between the extracts (methanol/dichloromethane, 1:1, v/v) of soybean paste and steamed soybean. The extracts were developed with chloroform/methanol/acetic acid (85:10:5, v/v), and separated into five groups according to the Rf values, respectively. Each group was assayed with the enzymatic method. The results showed different developing patterns on TLC and more potent activities of soybean paste groups.

For the purification, soybean paste was extracted with organic solvents (methanol/dichloromethane, 1:1, v/v), and the extract was fractionated using vacuum liquid chromatography with silical gel according to the hydrophobicities. Fractions showing relatively high activities of HMGR inhibition were further purified with Sephadex LH-20 column. Three groups having high inhibition activities were finally purified by C18 reverse phase preparative HPLC. Three main compounds were obtained. The structures of inhibitors were identified with LC-APCI+ MS, NMR, IR, and X-ray diffraction analyses.