Rheum rhaponticum and Rheum rhabarbarum Extracts as Modulators of Endothelial Cell Inflammatory Response

Abstract

Background: Inflammation, endothelial dysfunction, and alterations in blood physiology are key factors contributing to atherosclerosis and other cardiovascular disorders. Hence, modulation of endothelial function and reducing its pro-inflammatory and pro-thrombotic activity is considered one of the most important cardioprotective strategies. This study aimed to evaluate the anti-inflammatory potential of rhubarb extracts isolated from petioles and underground organs of Rheum rhabarbarum L. (garden rhubarb) and R. rhaponticum L. (rhapontic rhubarb) as well as two stilbenoids, typically found in these plants, i.e., rhapontigenin (RHPG) and its glycoside, rhaponticin (RHPT). Methods: Analysis of the anti-inflammatory effects of the indicated rhubarb-derived substances involved different aspects of the endothelial cells’ (HUVECs) response: release of the inflammatory mediators; cyclooxygenase (COX-2) and 5-lipoxygenase (5-LOX) expression as well as the recruitment of leukocytes to the activated HUVECs. The ability of the rhubarb-derived extracts to inhibit COX-2 and 5-LOX activities was examined as well. The study was supplemented with the in silico analysis of major components of the analyzed extracts’ interactions with COX-2 and 5-LOX. Results: The obtained results indicated that the examined plant extracts and stilbenes possess anti-inflammatory properties and influence the inflammatory response of endothelial cells. Biochemical and in silico tests revealed significant inhibition of COX-2, with special importance of rhaponticin, as a compound abundant in both plant species. In addition to the reduction in COX-2 gene expression and enzyme activity, a decrease in the cytokine level and leukocyte influx was observed. Biochemical tests and computational analyses indicate that some components of rhubarb extracts may act as COX-2 inhibitors, with marginal inhibitory effect on 5-LOX.

Kalanchoe sp. Extracts—Phytochemistry, Cytotoxic, and Antimicrobial Activities

“…The dependence of the signal intensity on the mobile phase composition was established using 20 reference standards differing in retention time and, therefore, the CAD response at the same concentration. Each reference standard was analyzed at 5 concentration levels (from 0.5 to 50 µg/mL) to obtain calibration curves, as proposed previously [ 61 ]. The concentration of each analyte was then calculated as a weighted average of the responses of the pair of adjacent calibration standards with RT lower and higher than the RT of the analyte.…”

Stilbenes, a Versatile Class of Natural Metabolites for Inflammation—An Overview

“…The gut microbiota has a direct effect on coronary heart diseases as it generates trimethylamine (TMA), which is reduced to trimethylamine N-oxide (TMAO), and increasing concentration of which can increase the risk of atherosclerosis. The administration of stilbenes can reduce trimethylamine N-oxide by regulating the TMA-producing microbes in the gut, with resveratroloside, rhaponticin and TSG showing the best ability [105].…”