Mechanistic insights into angiotensin-converting enzyme inhibition by Apium graveolens through an integrative in silico-in vitro study.

Angiotensin-converting enzyme (ACE) plays a central role in the renin-angiotensin system (RAS) and contributes to hypertension, a multifactorial disorder characterized by chronically elevated arterial pressure. Hypertension affects over one billion people worldwide and is a leading cause of cardiovascular morbidity and mortality. Although synthetic ACE inhibitors are effective, their long-term use is often limited by side effects such as cough and dizziness. Apium graveolens (AG) has been traditionally used to manage cardiovascular disorders, hyperlipidemia, and asthma, and is known for its antioxidant, anti-inflammatory, and neuroprotective properties. It was selected for this study due to its potential as a natural and safer ACE inhibitor. Most studies on plant-based ACE inhibitors are limited to preliminary screening or IC₅₀ estimation, whereas this study adopts an integrative approach linking computational, biochemical, and mechanistic analyses. Molecular docking identified bergapten and myrcene as top candidates with binding affinities comparable to lisinopril, and molecular dynamics simulations confirmed stable ligand-enzyme interactions with favourable energetics, supported by MM-GBSA analysis. In vitro enzyme assays corroborated these results, demonstrating significant and reversible ACE inhibition by both the extract and its constituents. Enzyme kinetic analyses revealed a non-competitive inhibition pattern for bergapten and myrcene, while the crude extract showed a mixed-type mechanism, suggesting synergistic modulation by multiple phytochemicals. Collectively, these findings highlight the mechanistic basis of ACE inhibition by A. graveolens and underscore its potential as a natural and safer therapeutic candidate for hypertension management.