Anti-inflammation and Anti-insulin Resistance of a Compound from Vietnamese <i>Clerodendrum chinense</i> Leaves

Abstract

Background: Clerodendrum chinense has been reported to possess several important biological activities. However, the anti-inflammation and insulin-related properties of isolated compounds from this plant have not yet been investigated. Objectives: This study focuses on extracting compounds and evaluating improvements in insulin resistance through the anti-inflammatory potential and inhibition of reactive oxygen species (ROS) of hispidulin from Vietnamese C. chinense leaves. Methods: Ethanol was used to separate the compounds from the leaves of Vietnamese C. chinense. 1D, 2D-NMR, and ESI-MS spectra were used to analyze the structural identity of the isolated compounds. Compound 1 (hispidulin) was evaluated for anti-inflammation and ROS in Raw 264.7 cells: Anti-inflammatory cytokine inhibition ability was analyzed by the ELISA method; Western blotting was used for the expression levels of phosphorylated ERK1/2, p38, p47phox, and GLUT4. ROS was assessed by immunofluorescence; a luminometer device was used to measure NADPH oxidase activity. The ability to absorb glucose and counteract insulin resistance was evaluated in 3T3-L1 cells via insulin-induced glucose uptake using immunofluorescence dye. Results: One compound isolated from the leaves of Vietnamese C. chinense was identified as hispidulin. Hispidulin at a concentration of 50 μg/mL significantly inhibited tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-8 in LPS-induced macrophages (P < 0.001). Moreover, in LPS-stimulated macrophages, the phosphorylation of p38 and ERK1/2, NADPH oxidase activity, as well as the phosphorylation of p47phox, were reduced at a concentration of 50 μg/mL of hispidulin (P < 0.001). More importantly, 3T3-L1 cells with inhibited insulin activity were able to regain glucose uptake and insulin responsiveness through GLUT4 expression when treated with 50 µg/mL of hispidulin (P < 0.001). Conclusions: The data confirmed the presence of hispidulin in the chemical composition of Vietnamese C. chinense leaves. The results indicated that hispidulin inhibited LPS- and ROS-mediated inflammation in macrophages. More importantly, the data have shown that hispidulin enhances glucose uptake and improves insulin activity in 3T3-L1 cells.