Lithospermum erythrorhizon sieb. et zucc. suppresses 3-hydroxy-3-methyl-glutaryl-coa reductase and induces ldl receptor expression in HepG2 cells

We examined the effects of Lithospermum erythrorhizon Sieb. et Zucc. (LE) on cholesterol metabolism in vitro. The ethanolic LE extract (ELE) had total polyphenolic and flavonoid contents of 353±7 and 285±51mg/dL, respectively. The ELE inhibited Cu²⁺-mediated LDL oxidation at <400μg/mL. In HepG2 cells treated with 400μg/mL ELE, the expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase decreased markedly (45%; P<0.05), whereas that of the LDL receptor increased (230%; P<0.05). The protein levels of both were altered similarly. The ELE also increased membrane-bound and cell-associated LDL particles, possibly via upregulation of the LDL receptor. In hepatocytes, 400μg/mL ELE affected surrogate markers of HDL and LDL synthesis: significant expression of apolipoprotein A-I was induced (20%; P<0.05), whereas that of apoB was suppressed (30%; P<0.05). In conclusion, ELE may improve cellular cholesterol metabolism by inhibiting cholesterol biosynthesis and apoB production, accelerating plasma LDL uptake and reducing LDL oxidation.