Endophytic fungi associated with Brucea mollis Wall. ex Kurz.: a hidden source of antimicrobial and antioxidant metabolites.

Geosmithia pallida (KU693285) was isolated from Brucea mollis an endangered medicinal plant of North-East India. The secondary metabolites, produced by the endophytic fungi, extracted by ethyl acetate were screened for antimicrobial activity. G. pallida extract displayed the highest antimicrobial activity against Candida albicans with a minimum inhibitory concentration of 80.5 ± 1.25 µg/mL. G. pallida also showed the highest antioxidant activity which differed insignificantly from Penicillium sp. (P > 0.05). The G. pallida extract also exhibited the highest cellulase activity and also amylase and protease activities. The cytotoxicity assay of the ethyl acetate extract of this endophyte showed negligible effect (1.93 ± 0.42%) on chromosomal aberration as compared to the control (cyclophosphamide monohydrate) (7.20 ± 1.51%). The internal transcribed spacer rDNA sequence of G. pallida was submitted to the NCBI (Accession number KU693285) from India for the first time. The FT-IR spectrophotometry of the bioactive metabolite of G. pallida showed the presence of different functional groups such as alcohol, carboxylic acids, amines, aromatics, alkyl halides, aliphatic amines and alkynes. The GC-MS analysis revealed the presence of acetic acid, 2-phenylethyl ester; tetracosane; cyclooctasiloxane hexadecamethyl; cyclononasiloxane octadecamethyl; octadecanoic acid; phthalic acid, di(2-propylpentyl) ester and nonadecane, 2,6,10,14,18-pentamethyl as the major compounds in the metabolite. The findings of the present work indicated G. pallida as a potential source of important biomolecules without mammalian cytotoxic effects, which can be utilized for pharmaceutical purposes.