Biological prospecting of endophytic fungi from the stem bark of Oroxylum indicum (L.) Kurz with antioxidant efficacy

Reactive oxygen species (ROS) require careful regulation in living organisms, as growing scientific evidence suggests their continuous production occurs even during typical cellular processes. Excessive production of ROS can lead to systemic oxidative stress, harming biological macromolecules and accelerating the aging process, diabetes, cancer, and other severe illnesses. This study investigated the presence of fungal endophytes associated with the stem bark of Oroxylum indicum (OI), and their phytochemical profile and antioxidant efficacy. We identified three fungal endophytes from two distinct genera. Three fungal endophytes namely, Simplicillium obclavatum (SC), Neopestalotiopsis clavispora (NC), and Trametes polyzona (TP) are the first to be documented from OI stem bark. The ethyl acetate extract of NC shown notable antioxidant activity against superoxide anion radical and (2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) free radical among the identified endophytes with the scavenging percentage value of 33.54 ± 0.4, 57.03 ± 0.69, and 37.41 ± 0.32, respectively, at the concentration of 100 μg/ml of the extract. The significant antioxidant activity of 24.07 ± 0.88 ascorbic acid equivalents was observed for NC extract. The mean total phenolic and total flavonoid content of NC extract was found to be 33.33 ± 0.22 and 38.90 ±1.17 gallic acid and quercetin equivalents, respectively, which was significantly higher compared to SC and TP isolates. Our study has provided insights on the presence of phytochemicals and their antioxidative potency in the isolated endophytic fungi from the stem bark of OI.