Endophytic fungi of Aegle marmelos as a source of novel antibacterials and anti-SARS-CoV agents.

Drug resistance in microorganisms is a growing global threat, highlighting the urgent need for novel therapeutic agents. This study evaluates the antibacterial and anti-SARS-CoV potential of fungal endophytes isolated from A. marmelos. Among 16 endophytes screened, the ethyl acetate extract of the #3 AMLBF strain (Fusarium vanettenii) exhibited the strongest antibacterial activity against several pathogens. This extract showed minimum inhibitory concentrations (MICs) ranging from 0.49 to 0.8 µg/ml. GC/MS analysis of the active extract identified 45 compounds. Furthermore, molecular docking against the SARS-CoV-2 spike glycoprotein revealed nine potential ligands, with Anthraergosta-5,7,9,22-tetren-3-ol p-chlorobenzoate showing the most potent binding affinity (- 10.2 kcal/mol), a value exceeding that of the standard chloroquine (- 6.5 kcal/mol). These results indicate that the organic extract from this fungal strain is a promising candidate for the discovery of new antimicrobial agents.