In Silico Modeling and Bioguided Isolation Synergize to Discover Antifungal Compounds from Bitter Orange Peel

Abstract

The antifungal potential of C. aurantium (bitter orange) peel extracts was investigated using an integrated computational and experimental approach with S. cerevisiae as a model organism. Hexane (SPH) and acetone (SPA) extracts exhibited moderate antifungal activity, yielding five bioactive fractions (B1, B2 from SPH; H2, F8, F9 from SPA) via bioguided fractionation. GC-MS and HPLC-DAD identified limonene (36.15%) and naringenin (23.94%) as major constituents. Molecular docking against a fungal plasma membrane model revealed that SPH-derived terpenoids (limonene, α-pinene) bind directly to ergosterol (ΔG bind = -6.07 and -6.40 kcal/mol), mirroring the mechanism of nystatin (ΔG bind = -13.58 kcal/mol). Similarity analysis identified a common 2-heptene substructure supporting this mechanism (Tanimoto coefficients: 0.11-0.13). For SPA-derived compounds, Petra/OSIRIS/Molinspiration analyses predicted favorable drug-likeness, Lipinski compliance (NV ≤ 1), and drug scores of 0.39-0.75, with caffeic acid, catechin, and p-coumaric acid showing the highest potential. TLC coupled with logP predictions attributed carotenoids/terpenoids to SPH (cLogP 2.30-3.62) and aglycone flavonoids/phenolic acids to SPA (cLogP -1.69 to 2.16). This study demonstrates C. aurantium peel as a sustainable source of antifungal compounds, validated through integrated computational and experimental workflows.