Endophytic Fungi from Solanum pseudocapsicum as a source of antibacterial metabolites: isolation, identification, and molecular docking insights

Antibacterial resistance reduces the effectiveness of current therapies, necessitating the discovery of new bioactive compounds. This study isolated and characterised endophytic fungi from Solanum pseudocapsicum L. collected in West Sumatra, Indonesia, and evaluated their antibacterial potential. Eleven isolates were obtained, and ethyl acetate extracts from rice-based cultures were screened against Staphylococcus aureus, MRSA, and Escherichia coli. Two isolates showed the strongest activity: SPD3 inhibited S. aureus (18.68 ± 0.55 mm) and MRSA (18.17 ± 0.30 mm), while SPA3 inhibited E. coli (15.01 ± 0.45 mm). Phytochemical analysis indicated the presence of alkaloids, terpenoids, and steroids. Molecular identification classified SPD3 as Aspergillus fumigatus and SPA3 as Fusarium solani. LC-MS/MS analysis suggested that Fumigaclavine C and Cinchonidine were the major metabolites. Docking with PBP2a (4CJN) revealed that both compounds bind to the allosteric site (−5.14 and −5.00 kcal/mol), supporting an inhibition mechanism mediated through allosteric modulation rather than direct active-site interaction.