Naturally occurring HMGB1 inhibitor delineating the anti-hepatitis B virus mechanism of glycyrrhizin via in vitro and in silico studies

Abstract

Owing to have various limitations in approved therapeutic drugs such as lamivudine and interferons there is an unmet need for screening of plant derived natural products to treat the hepatitis B virus (HBV) disease effectively. Present study evaluates the antiHBV potential of glycyrrhizin in HepG2 cells by usingan in-vitroand computational approach.Non-toxic doses of glycyrrhizin were evaluated using an MTT assay and were observed that below 400 µM of glycyrrhizin is significantly non-toxic to HepG2 cells. After transient transfection of HepG2 cells with wild type construct (pHBV 1.3X) followed by dose-dependent treatment with glycyrrhizin, our ELISA assay results revealed that glycyrrhizin significantly inhibited secreted HBV surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg).To evaluate whether glycyrrhizin inhibits the replication of HBV, our Real-Time PCR results demonstrated a significant reduction in replicative intermediates of HBV DNA and covalently closed circular DNA (cccDNA) in pHBV-HepG2 transfected cells. A 3D crystal structure of HMGB1 (High mobility group box 1 protein)(1AAB) protein was formed and docked with glycyrrhizin and lamivudine. We performed 100 ns MD simulations analysis of HMGB1 and HMGB1-glycyrrhizin complex. The Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) properties were estimated by using SwissADME and AdmetSAR web tool. Our results validated that glycyrrhizin considerably decreases HBsAg, HBeAg secretion; extracellular HBV DNA and covalently closed circular DNA (cccDNA) in dose a dependent manner. Docking of glycyrrhizin and lamivudine (positive control) showed a good binding affinity with the active-site residues of the HMGB1 and formed stable complex (ΔG = − 7.0 kcal mol−1) and (ΔG = − 4.3 kcal mol−1) respectively, which might be responsible for its antiviral activity. Glycyrrhizin forms a stable complex with HMGB1 withoutcausing any considerable conformational switching in the protein structure. Glycyrrhizin acts as an HMGB1 inhibitor performed by computational approaches. Our study indicates the potential application of glycyrrhizin as a promising class antiHBV candidate.