Large-scale virtual screening of 17,967 IMPPAT phytochemicals identifies multiple CDR1 binders and reveals Apigenin-7-O-glucuronide as a putative CDR1-GSC1 dual-target lead against Candida albicans with initial in-vitro evidence.

چکیده اصلی

The increasing incidence of antifungal resistance in Candida albicans, mainly mediated by multidrug efflux transporters and alterations of cell-wall biosynthesis, requires the discovery of new antifungal compounds targeting multiple pathways involved in resistance. In the present study, we employed an integrated computational-experimental workflow to identify potential antifungal phytochemicals from the Indian Medicinal Plants, Phytochemistry and Therapeutics (IMPPAT) database. In the virtual screening, a total of 17,967 phytochemicals were screened against the ATP-binding cassette efflux transporter CDR1, followed by molecular docking, drug-likeness assessment, ADMET filtering, molecular dynamics (MD) simulations, and MM/PBSA binding free-energy calculations. Based on cross-target molecular docking, molecular dynamics simulations, and MM/PBSA analyses of the top ten CDR1 phytochemicals against other antifungal resistance-associated proteins revealed that Apigenin-7-O-glucuronide is the only compound that exhibited favourable interactions with both CDR1 and GSC1, indicating its potential as a putative dual-target inhibitor. Molecular dynamics simulations showed the stability of the protein-ligand interactions, and MM/PBSA analysis confirmed Apigenin-7-O-glucuronide as the most energetically favourable CDR1 inhibitor (ΔGtotal = -35.56 kJ mol-1), and also showed favourable binding with GSC1 (ΔGtotal = -11.69 kJ mol-1). The HR-LCMS analysis of hydroethanolic extract of Eucalyptus camaldulensis gave putative evidence of presence of Apigenin-7-O-glucuronide based on accurate mass and database matches. The extract also showed concentration-dependent antifungal activity against Candida albicans ATCC 10231 and environmental drug-resistant Candida and emerging pathogenic yeast isolates with minimum inhibitory concentration (MIC) of 1.56 mg/mL and minimum fungicidal concentration (MFC) of 6.25 mg/mL. Since the biological evaluation was performed using a crude hydroethanolic extract rather than the purified phytochemical, the observed antifungal activity cannot be exclusively attributed to Apigenin-7-O-glucuronide but provides preliminary biological support for the computational predictions and highlights the need for future validation using the purified compound and target-specific mechanistic studies. Together, these findings identify Apigenin-7-O-glucuronide as a putative dual-target antifungal lead and demonstrate the value of integrating large-scale virtual screening with preliminary biological evaluation for natural product-based antifungal drug discovery.

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