Isolation, characterization, and in silico analysis of a bioactive compound citrinin from Aspergillus terreus (OP480427) with antagonistic activity against the toxigenic fungus Aspergillus flavus (OP600575).

The study investigates the antifungal potential of citrinin, the bioactive compound isolated from Aspergillus terreus (OP480427), against aflatoxin-producing fungi isolated from wheat rhizospheric soil and its ability to interfere with aflatoxin biosynthesis. Citrinin, purified using TLC, identified through polyphasic characterisation, effectively inhibited the growth of Aspergillus flavus (OP600575) and reduced aflatoxin production, a major food safety concern. Structural characterisation was performed using FTIR, HRMS and NMR. The reduction of aflatoxin levels was confirmed by HPLC analysis. The chloroform extract containing 1000 µg/mL citrinin produced an inhibition zone of 16 mm, which decreased to 8 mm at 500 µg/mL and further to 4 mm at 250 µg/mL. In silico docking revealed that citrinin targets key enzymes in the aflatoxin biosynthesis, explaining its dual role as a fungal growth inhibitor and a toxin suppressant. Findings suggest that citrinin is a promising natural agent for controlling A. flavus and aflatoxin production in agriculture. It may serve as a potential lead for antifungal drug development, as a valuable source of bioactive metabolites for sustainable crop protection.