Isolation, identification and biological evaluation of endophytic fungi from Andrographis paniculata with special reference to antioxidant, antimicrobial and anticancer activities.

Andrographis paniculata is an important medicinal plant containing diverse bioactive constituents and is also a potential host for endophytic fungi capable of producing pharmacologically relevant secondary metabolites. The present study aimed to isolate and characterize endophytic fungi associated with the leaves of A. paniculata and to evaluate their phytochemical composition, antioxidant, antimicrobial, and anticancer potential. Thirteen endophytic fungal isolates belonging to the genera Colletotrichum, Acremonium, and Fusarium were isolated and characterized using morphological and molecular approaches. Four fractions were selected for testing of anticancer activity among thirteen isolates. Fungal metabolites were extracted using methanol, chloroform, and ethyl acetate and subjected to qualitative and quantitative phytochemical analysis. Antioxidant activity was evaluated using DPPH and FRAP assays, while antimicrobial activity was assessed against selected bacterial and fungal pathogens. Selected fungal fractions were further evaluated for cytotoxic activity against HeLa cells using the MTT assay. GC-MS analysis was performed on selected biologically active fractions for preliminary characterization of their chemical constituents. Among the tested fractions, the methanolic fraction of Colletotrichum sp. AD-12 exhibited the highest DPPH radical-scavenging activity (60.77 ± 4.71%), whereas the ethyl acetate fraction of Colletotrichum sp. AD-06 demonstrated the highest cytotoxic activity against HeLa cells (44.20 ± 5.05% inhibition). GC-MS analysis revealed chemically diverse constituents belonging to several compound classes, including alkanes, phenolic compounds, aromatic hydrocarbons, fatty-acid derivatives, and other metabolites. The findings indicate that A. paniculata-associated endophytic fungi possess diverse preliminary biological and chemical potential. Further studies involving compound purification, MIC/MBC determination, concentration-dependent cytotoxicity and IC₅₀ estimation, and mechanistic validation are required to establish the therapeutic significance of the identified metabolites.