Antioxidant and antibacterial activity of extracts and compounds from endophytic fungi isolated from roots of Physalis angulata and their combination effects

Natural products sourced from endophytic fungal are recognized as one of the most important resources for drug discovery and molecular diversity. Utilizing combinations of extracts or pure compounds can produce synergistic effects, offering strong pharmacological efficacy at relatively low concentrations. Physalis angulata L. is a medicinal plant traditionally used by people globally. The endophytic fungi associated with this plant represent a valuable, yet underexplored, source of bioactive compounds. This study aimed to identify extracts and pure compounds from endophytic fungi isolated from the roots of P. angulata that exhibit antioxidant and antibacterial activities, as well as to explore their combined effects. The endophytic fungi isolates used in this study were obtained from P. angulata roots stored in the laboratory as stock cultures. Each isolate was re-identified morphologically for purity and cultivated in Potato Dextrose Broth (PDB) media for 4 weeks at room temperature under static conditions. Liquid culture was extracted in ethyl acetate and evaporated. Antioxidant and antibacterial activities were tested for each endophytic fungal extract, followed by the isolation of active compounds from the selected extracts. The chemical structures were elucidated using spectroscopic techniques, such as 1D and 2D NMR. The endophytic fungi responsible for producing bioactive compounds were identified through molecular analysis. Combination effects were examined on both extracts and pure compounds exhibiting antioxidant and antibacterial activities. The extract of Trichoderma virens endophytic fungi, which produced two bioactive compounds, demonstrated the highest antioxidant and antibacterial activities. Spectroscopic analysis indicated that the two compounds were 10-hydroxy-benzoisochromen-1-one (1) and 7-hydroxy-benzochromen-6-one (2). Molecular identification and phylogenetic analysis of the selected endophytic fungi showed a high similarity to Trichoderma virens. The best combination effect with strong antioxidant activity was found in the CA4+CA6 blend (test 3). The antioxidant activity of compounds 1, 2, and their combination products exhibited weak antioxidant activity. The highest antibacterial activity (≥ 95%) for the combination product was derived from synergistic effects (27.8%) and additive effects (13.9%). Compound 1 had strong antibacterial activity compared to compound 2 and their combination products. Thus, for the development of Trichoderma virens as a source of medicinal substances, extract combinations are more efficient than pure compound combinations.