Inhibitory Effects of S-Allylmercaptocysteine Derived from Aged Garlic on Cholesterol Biosynthesis in Hepatocytes

The present study was undertaken to elucidate the mechanisms underlying the cholesterol-lowering effect of S-allylmercaptocysteine (SAMC) derived from aged garlic. Rat hepotocytes and HepG2 cells were used to determine the short-term effects of SAMC on [$^{14}C$] acetate incorporation into cholesterol, and several enzymatic steps. The cells were grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum and treated with 20, 40, 60 and 80 ${\mu}g/ml$ of SAMC. At concentration of 20~40 ${\mu}g/ml$, no significant cells viability effect was noted during those incubation periods. However, at a concentration 60 ${\mu}g/ml$, cell viability decreased approximately 50% compared with the control. The treatment of cells with 5, 10, 15, and 20 ${\mu}g/ml$ of SAMC resulted in a marked of [$^{14}C$]-acetate incorporation into cholesterol. At concentration of 15 ${\mu}g/ml$, the cholesterol synthesis was inhibited 79% in cells. The activities of lipogenic enzymes, fatty acid synthase (FAS), and glucose-6-phosphate dehydrogenase (G3PDH) were measured in culture hepatocytes treated with the inhibitors. The activity of FAS in cells treated with 0.95 nmol SAMC was 19% lower than that of nontreated cells, and no affected G6PDH activity, 3-hydroxy-3-methylglutaryl Co A activity was decreased at concentration dependant manner. The present study demonstrates that SAMC is effective in inhibiting cholesterol biosynthesis.

마늘 숙성 중 생성되는 S-allylmercaptocysteine의 콜레스테롤 생합성 억제 효과에 대하여 Hepatocytes를 이용하여 조사하였다. HepG2 cells을 Dulbecco's modified Eagle's medium (DMEM)에 배양하여 S-allylmercaptocysteine의 농도를 20, 40, 60, 80 및 100 mL 씩 각각 첨가하여 cell viability를 살펴본 결과 20~40 ${\mu}g/mL$에서는 높았으며, 60 ${\mu}g/mL$ 농도에서 약 50%가 유지되었다. S-allylmercaptocysteine을 5, 10, 15 및 20 ${\mu}g/mL$ 농도로 [$^{14}C$]-acetatecholesterol에서 처리하였을 경우 15 ${\mu}g/mL$ 농도에서 cholesterol 생합성이 79%로 억제되었다. Fatty acid synthase의 활성은 0.95 nmol에서 19%의 억제효과를 나타내었으나, Glucose 6-phosphate dehydrogenase (G6PDH)의 활성에는 거의 영향을 미치지 않았다. S-allylmercaptocysteine의 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase의 활성은 용량 의존형으로 감소하였다. 이상의 결과로 보아 마늘 숙성 과정에서 생성되는 주요 성분인 S-allylmercaptocysteine은 간 세포에서 cholesterol의 생합성을 억제하는데 기여하는 것으로 나타났다.