Computational discovery of microalgal metabolites as dual-target inhibitors against Plasmodium falciparum glutathione S-transferase and apical membrane antigen 1 for resistance-circumventing antimalarial therapy

Abstract

Malaria remains a significant global health problem; with the potential for developing resistance to conventional antimalarials justifying novel therapeutic approaches. This study investigates the potential of microalgal metabolites as dual-inhibitors of Plasmodium falciparum glutathione S-transferase (PfGST) and apical membrane antigen 1 (AMA1); two of the most important proteins in parasite survival and host cell invasion. By high-throughput molecular docking simulations; we studied binding energy distributions; conformational characteristics by principal component analysis; pharmacophoric and pharmacokinetic research with structure-activity relationships of its inhibitors. Our findings indicate various patterns of interactions: PfGST exhibits a unimodal distribution of binding energy with a maximum at -7.2 kcal/mol; whereas AMA1 exhibits a bimodal distribution with minimum at -6.8 and − 8.3 kcal/mol; suggesting various mechanisms of binding. Specifically; platencin was among the most potent dual-inhibitors with binding energies of -7.30 kcal/mol to PfGST and − 8.20 kcal/mol to AMA1. Pharmacophoric characteristics were found to be the hydrogen-bond acceptors; hydrophobic centers; and aromatic rings as determinants of dual-target activity; the optimal dual-target inhibitory potential occurring with compounds of balanced physicochemical properties. High-resolution molecular interaction mapping validated that while the two targets identify overlapping classes of interactions with the metabolites; PfGST interaction is dominated by hydrophobic contacts and AMA1 exploits higher electrostatic complementarity and hydrogen-bonding networks. ADMET profiling also revealed favorable drug-likeness in dual-inhibitory compounds of intermediate molecular size (420–500 Da) and moderate lipophilicity (LogP 3–6). This study provides a structural basis for rationale design of antimalarial compounds from microalgal metabolites. Our findings confirm the conformational selection hypothesis; in which these compounds selectively bind to and stabilize protein conformations that inhibit parasite function; possibly circumventing known resistance mechanisms.