Inhibition of Vascular Smooth Muscle Cell Proliferation by Gentiana lutea Root Extracts

Abstract

Gentiana lutea belonging to the Gentianaceae family of flowering plants are routinely used in traditional Serbian medicine for their beneficial gastro-intestinal and anti-inflammatory properties. The aim of the study was to determine whether aqueous root extracts of Gentiana lutea consisting of gentiopicroside, gentisin, bellidifolin-8-O-glucoside, demethylbellidifolin-8-O-glucoside, isovitexin, swertiamarin and amarogentin prevents proliferation of aortic smooth muscle cells in response to PDGF-BB. Cell proliferation and cell cycle analysis were performed based on alamar blue assay and propidium iodide labeling respectively. In primary cultures of rat aortic smooth muscle cells (RASMCs), PDGF-BB (20 ng/ml) induced a two-fold increase in cell proliferation which was significantly blocked by the root extract (1 mg/ml). The root extract also prevented the S-phase entry of synchronized cells in response to PDGF. Furthermore, PDGF-BB induced ERK1/2 activation and consequent increase in cellular nitric oxide (NO) levels were also blocked by the extract. These effects of extract were due to blockade of PDGF-BB induced expression of iNOS, cyclin D1 and proliferating cell nuclear antigen (PCNA). Docking analysis of the extract components on MEK1, the upstream ERK1/2 activating kinase using AutoDock4, indicated a likely binding of isovitexin to the inhibitor binding site of MEK1. Experiments performed with purified isovitexin demonstrated that it successfully blocks PDGF-induced ERK1/2 activation and proliferation of RASMCs in cell culture. Thus, Gentiana lutea can provide novel candidates for prevention and treatment of atherosclerosis.

Role of Polyphenols and Other Phytochemicals on Molecular Signaling

“…Additionally it has been shown that both catechins and EGCG suppress PDGF-BB induced activation of PDGF-receptor mediated signal transduction pathways in VSMC by blocking tyrosine phosphorylation and their downstream molecular targets [ 99 ]. These findings are consistent with our recent study on antiproliferative effect of Gentiana lutea and its main constituent isovitexin where Kesavan et al have reported aqueous root extract of G. lutea and isovitexin significantly inhibit PDGF-BB induced proliferation of SMC by downregulation of ERK1/2 and iNOS expression [ 100 ]. Similarly in another study we have shown significant antiproliferative effect of ellagic acid (EA), phenolic compound present mainly in barriers, which might be due to prevention of PDGF-BB receptor tyrosine phosphorylation/activation, reduced ROS generation, and downstream stimulation of ERK1/2 [ 101 ].…”

Bitter taste receptor agonists elicit G‐protein‐dependent negative inotropy in the murine heart

“…To this end, it may be possible to take advantage of the genomic clustering of the Tas2r to simultaneously knock out multiple receptors. Alternatively, as has been done for one TAS2R , generation of humanized mice expressing tissue‐specific human taste GPCRs may be a profitable approach in the future (69).…”

Naturally Occurring Variants of the Dysglycemic Peptide Pancreastatin

“…Cells-NO levels in L6 cells were measured by the 4,5-diaminofluorescein diacetate method as described previously (19). Briefly, L6 cells were seeded in 24-well plates.…”