The chemical profiling of ethyl acetate extract of the endophytic fungus Pleosporales sp. using liquid chromatography–electrospray ionization–mass spectrometry (LC-ESI-MS) revealed the presence of 12 metabolites of different chemical classes such as steroids, α-pyrones, asterric acid derivatives, and quinones. Additionally, the gas chromatography–mass spectrometry (GC-MS) profiling of the ethyl acetate (EtOAc) and methanol extracts exhibited the presence of fatty acids and their esters, in which methyl palmitate (18.72%, and 25.48%, respectively) and methyl linoleate (11.92% and 23.39%, respectively) were found in both extracts. On the other hand, palmitic acid (12.60%), methyl oleate (26.90%), oleic acid (4.01%) and linoleic acid (3.25%) were present only in methanol extract. Furthermore, ethyl palmitate (12.60%), 13-octadecenoic acid (19.36%), and ethyl linoleate (3.25%) occurred in EtOAc extract. A phytochemical investigation of both extracts led to the isolation of fatty acids such as palmitic acid (18), oleic acid (20), and linoleic acid (21) and their esters including methyl palmitate (13), methyl stearate (22), methyl linoleate (16), methyl 3-hydroxy-5-methylhexanoate (23), and monomethyl azelate (27), in addition to monoacyl derivatives of glycerol such as 3,3-dihydroxypropyl hexadecanoate (24), 2,3-dihydroxypropyl elaidate (25), and 1-linoleoyl-sn-glycerol (26). The structures of the isolated compounds were identified by different spectroscopic analyses including 1H- and 13C-NMR and GC-MS. The EtOAc extract exhibited a cytotoxic effect against MCF-7 and HepG-2 cell lines, with IC50 values of 4.12 ± 0.10 and 10.05 ± 0.05 μg/mL, respectively.
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