Aspergillus niger as a New Endophytic Fungus From Deverra tortuosa: Phytochemical Profile, Molecular Docking, Antimicrobial, Antibiofilm, Antioxidant, and Anticancer Activities.

Endophytic fungi are recognized as rich sources of bioactive secondary metabolites with promising pharmaceutical applications. In this study, five endophytic fungal isolates were obtained from Deverra tortuosa and evaluated for antimicrobial activity for the first time. Among them, isolate AA1 showed the highest antimicrobial potential and was identified as Aspergillus niger (GenBank accession no. PX273401.1) through morphological and molecular analyses. Phytochemical analysis revealed high levels of flavonoids (496.5 µg/mL), tannins (260.7 µg/mL), phenolics (214.93 µg/mL), and alkaloids (26.45 µg/mL). GC-MS profiling detected several bioactive metabolites, with hexadecenoic acid, docosene, octadecanol, isochiapin B, octadecenoic acid, and octacosanol as major constituents. The fungal extract exhibited potent antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, and Bacillus cereus, each with a minimum inhibitory concentration (MIC) of 62.5 µg/mL. It also inhibited biofilm formation by 26.9:55.1% at ½ MIC and demonstrated notable antioxidant activity, with half maximal inhibitory concentration (IC₅₀) values of 167.6 µg/mL (DPPH) and 137.8 µg/mL (ABTS). Cytotoxicity assays confirmed relatively low toxicity toward normal Wi-38 and Vero cell lines, while significant antiproliferative activity was observed against MCF-7 and HepG2 cancer cells, with IC₅₀ values of 78.7 and 29.5 µg/mL, respectively, indicating favorable selectivity. Molecular docking supported these biological activities, identifying hexadecenoic acid as the strongest ligand against DNA gyrase subunit B (GyrB) and estrogen receptor alpha (ERα), while isochiapin B also showed strong affinity toward ERα. These findings demonstrate that A. niger from D. tortuosa is a promising source of multifunctional bioactive metabolites with antimicrobial, antioxidant, and anticancer potential for future pharmaceutical applications.