Phytochemical profiling, antioxidant capacity and indole-3-acetic acid production by endophytic fungi and bacteria isolated from Achyranthes aspera L.
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Endophytic microorganisms associated with medicinal plants are recognized as promising sources of bioactive secondary metabolites with applications in pharmaceuticals and sustainable agriculture. In this study, endophytic bacteria and fungi were isolated from Achyranthes aspera and evaluated for their phytochemical composition, antioxidant activity, and plant growth–promoting potential. Endophytes were obtained from surface-sterilized tissues and identified using morphological and molecular approaches. Quantitative analysis revealed significant variation in phytochemicals, including phenolics, flavonoids, alkaloids, and tannins. Aspergillus sp. exhibited the highest levels of phenolics (11.21 ± 0.18 mg GAE/mL), flavonoids (3.83 ± 0.31 mg RE/mL), alkaloids (1.42 ± 0.09 mg/mL), and antioxidant activity (2.84 ± 0.12 mg AAE/mL), followed by the black fungal isolate, while bacterial isolates showed comparatively lower activity. All isolates produced indole-3-acetic acid (IAA), with Aspergillus sp. showing the highest production (229.1 ± 12.6 µg/mL). LC–MS analysis confirmed the presence of IAA and kinetin in Aspergillus sp., indicating the production of multiple phytohormones. These findings highlight the superior metabolic capability of fungal endophytes and their potential as sustainable sources of natural antioxidants and plant growth–promoting agents.
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