Isolation, characterization, and docking analysis of endophytic Aspergillus ochraceus NRRL398 metabolites from Eclipta prostrata (L.) L. targeting acetylcholinesterase inhibition

Eclipta prostrata (False Daisy) is widely acknowledged in traditional medicine for its neuroprotective properties, primarily due to its abundant flavonoids and coumestans. However, the chemical and pharmacological potential of its associated endophytic fungi remains underexplored. In this study, we report for the first time the isolation of Aspergillus ochraceus NRRL398 as an endophyte from E. prostrata, and the subsequent isolation and characterization of nine bioactive secondary metabolites from its n-butanol fraction (EPSF-1-NB). Notably, this is the first report of Apigenin and Luteolin being produced by this fungal endophyte, highlighting its unprecedented biosynthetic capability. The isolated compounds comprising two triterpenoids, one phytosterol, two coumestan derivatives, and four flavonoids were structurally elucidated using advanced chromatographic and spectroscopic techniques. In-silico molecular docking against acetylcholinesterase (AChE, PDB ID: 1QTI) using SYBYL-X 2.0 software revealed that Apigenin and Luteolin exhibited the strongest binding affinities with C-scores of 6.93 and 6.88, respectively, outperforming other compounds such as Wedelolactone (5.48), dimethylwedelolactone (5.05), and sterol/triterpenoid constituents. This study provides novel insight into the metabolic versatility of A. ochraceus as an endophyte of E. prostrata, and identifies Apigenin and Luteolin as promising AChE inhibitors of fungal origin. These findings open new avenues for exploring fungal endophytes as untapped sources of neuroprotective agents and warrant further in-vitro and in-vivo validation.