Isorhamnetin is a flavonoid present in many plants. In a previous in vivo study, isorhamnetin lowered serum cholesterol of rats fed high-cholesterol diet. However, its mechanism of action was not investigated. In the present work, the mechanism of its hypocholesterolemic effect was studied. The expression of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) and low-density lipoprotein receptor (LDLR) genes and proteins was studied in HepG2 liver cancer cell line by polymerase chain reaction, western blot, and indirect enzyme-linked immunosorbent assay as well as its antioxidant activity. sorhamnetin had an IC 50 of 100, 53, and 40 µM at 24, 48, and 72 hours, respectively, in HepG2 cells. Isorhamnetin downregulated HMG-CoA reductase gene expression significantly. Also, all tested doses of isorhamnetin downregulated LDLR expression and produced no change in membranous LDLR protein expression. In cell lysate, LDLR was increased by all studied concentrations of isorhamnetin. Isorhamnetin (100 µM) decreased intracellular HMG-CoA reductase compared to vehicle-treated control. Furthermore, isorhamnetin increased superoxide dismutase activity and reduced H 2 O 2 level, due to catalase activity. Isorhamnetin reduced HMG-CoA reductase gene expression and increased total LDLR and exerted pronounced antioxidant action.
Context: Rhamnetin is a naturally occurring methylated derivative of quercetin. This flavonoid is abundant in Syzygium aromaticum, Coriandrum sativum Prunus cerasus, and Rhamnus spp. Aims: To evaluate the effects of rhamnetin on HMG-CoA reductase and low-density lipoprotein receptor (LDLR) gene and protein expressions in the HepG2 hepatoma cell line. Methods: The expression of HMG-CoA reductase and LDLR genes and proteins were studied in HepG2 liver cancer cell line by PCR, Western blot, and indirect ELISA, as well as their antioxidant activity. Results: Rhamnetin was non-toxic up to 200 μM on HepG2 at 24, 48, and 72 h. Rhamnetin (25 µM) upregulated LDLR gene expression by 1.66 folds compared to 3.12 folds exerted by the well-known hypocholesterolemic drug simvastatin. Rhamnetin (100 µM) increased the expression of LDLR protein at the cell membrane, while the other concentrations produced no significant change from the control (vehicle-treated). In HepG2 cell lysate, LDLR was increased by 50 µM of rhamnetin. Also, rhamnetin increased SOD activity significantly by 100.98, 86.28, and 100.98% by the concentrations 25, 50, and 100 µM, respectively. Using the same concentrations, rhamnetin reduced H2O2 levels by 50, 67, and 76.34%, respectively. Conclusions: This study demonstrated for the first time that rhamnetin reduced HMG-CoA reductase gene expression and increased LDLR in HepG2 cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.