An investigation on the cardioprotective potential of lichen compound protocetraric acid by HO-induced toxicity in H9c2 rat heart cells through in vitro and in silico analysis.

Worldwide, cardiovascular diseases (CVDs) are the leading cause of death and require treatment and prevention. Lichens are symbiotic organisms that are known to produce unique secondary metabolites and have been used as folk medicines. The aim of the study is to emphasize the importance of lichens in improving heart health, with the objective of investigating protocetraric acid, a lichen metabolite, for its antioxidant and cardioprotective potential by using in vitro and in silico techniques. Protocetraric acid (PRC) was isolated, characterized, and tested for antioxidant properties using six assays. In cardiovascular investigations, hydroxymethylglutaryl-coenzymeA reductase (HMGCR), angiotensin-converting enzyme inhibitory, and fibrinolytic capacities, along with enzyme inhibitory kinetics studies, were carried out. In silico toxicology and molecular docking analysis were done to determine the binding sites on target proteins. The cytoprotective ability of PRC was evaluated by HO-induced toxicity in H9c2 rat heart cells. Out of six lichens, the extract of F. caperata showed comparatively stronger antioxidant activity in terms of 1,1-diphenyl-2-picryl hydrazil (DPPH), scavenging of nitric oxide (SNO), and ferric reducing potential (FRAP) equivalent values. PRC showed significant antioxidant properties, and with respect to cardiovascular studies, PRC exhibited 86% HMGCR and 82% ACE inhibition, while 57% fibrinolysis at 320 µM concentration. Inhibitory kinetic tests of PRC showed competitive and uncompetitive HMGCR and ACE inhibition types respectively. PRC showed minimum binding energies of - 7.9, - 8.9, and - 9.0 kcal/mol with 1HWK, 1O8A, and 4BZS. The H9c2 cell line pre-treated with PRC was found to reduce HO toxicity as well as increase cell viability. Protocetraric acid is a potent compound that has been experimentally shown to have hypocholesterolemic, hypotensive, and cardioprotective properties for treating cardiovascular diseases.