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

Abstract

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.