Anti-inflammation and Anti-insulin Resistance of a Compound from Vietnamese Clerodendrum chinense Leaves

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.

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.

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.

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).

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.