In Vitro Antioxidant and Antibacterial Activities of Ethyl Acetate Extracts of Ziziphus lotus Leaves and Five Associated Endophytic Fungi

The exploration of new pharmacological compounds from endophytic fungi offers infinite possibilities. The aim of this study was to evaluate the antibacterial and antioxidant activities of extracts from the leaves of Ziziphus lotus and five of its endophytic fungi and investigate the chemical diversity of the secondary metabolites produced. Isolated, purified, and molecularly identified endophytes and plant leaves were subjected to ethyl acetate extraction. The antibacterial potential of the extracts was assessed by the disc diffusion method against five bacterial strains: Staphylococcus aureus ATCC 25923; Staphylococcus aureus MU50; Enterococcus faecalis WDCM00009; Escherichia coli ATCC 25922; and Pseudomonas aeruginosa ATCC 27853. DPPH and reducing power tests were performed to assess antioxidant potential. GC–MS analysis was used to identify volatile compounds in extracts. Fungal endophytes were identified as Aspergillus cavernicola, Aspergillus persii, Alternaria alternata, Cladosporium asperlatum, and Fusarium incarnatum–equiseti complex, with respective accession numbers DTO 412-G6, DTO 412-I5, DTO 413-E7, DTO 412-G4, and DTO 414-I2. GC–MS analysis revealed a large number of bioactive compounds. All extracts showed antibacterial activity against at least two of the bacteria tested, and most showed antioxidant activity. The Aspergillus cavernicola extract stood out for its higher phenolic content and higher antioxidant and antibacterial activities in all tests.