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From ancient times, plants and plant derived products are exploited as a prominent source of folkloric medicines with tremendous therapeutic potential for an array of health disorders. In the present study, ethanolic leaf extract of Hibiscus sabdariffa and Croton caudatus were evaluated for free radical scavenging activity in Saccharomyces cerevisiae model system. H. sabdariffa and C. caudatus showed tremendous DPPH free radical scavenging potential with an IC50 value of 184.88 and 305.39 µg/mL respectively at a concentration of 500 µg/mL. The ethanolic leaf extract of H. sabdariffa and C. caudatus also showed significant hydoxyl radical scavenging and total antioxidant activity. Ascorbic acid was used as positive control. The in vitro antioxidant activity was further supported by in vivo studies using radical scavenging mechanism in S. cerevisiae wild type and its isogenic deletion strains sod1∆ and tsa1∆. The mutant yeast cells substantially scavenged the stress generated by H2O2 when supplemented with ethanolic leaf extract of H. sabdariffa and C. caudatus as evident from spot assays followed by fluorescence assay (DCF-DA) using fluorescence microscopic and intensity studies. H. sabdariffa and C.caudatus significantly neutralize the ROS level in yeast mutants with concomitant decrease in fluorescence intensity as compared to the untreated yeast cells. The results suggested the efficacy of H. sabdariffa and C. caudatus as potent antioxidants in yeast system and thus their futuristic applications in therapeutics.

BACKGROUND From ancient times, plants and plant derived products are used as folkloric medicines in a variety of health disorders owing to their tremendous therapeutic potential. The present study aims to determine the antioxidant efficacy of crude Acacia nilotica extract in oxidative stress response system of Saccharomyces cerevisiae as model organism. RESULTS A. nilotica showed significant antioxidant activity with an IC50 value of 75.157 and 159.57 µg mL−1 for DPPH radical and hydroxyl radical scavenging activity respectively at a concentration of 500 µg mL−1. The total antioxidant activity of A. nilotica showed an ascorbic acid equivalent of 152.79 ± 7.43 µg mL−1. The presence of phytoconstituents such as phytol and alpha-tocopherol from GC-MS analysis confirmed the potential of A. nilotica as an antioxidant. The results were validated using stress response mechanism in S. cerevisiae wild type and its isogenic deletion strains, sod1∆ and tsa1∆. A. nilotica substantially neutralize the ROS level generated by H2O2 in mutant strains as evident from spot assay and fluorescence assay (DCF-DA) using fluorescence microscopy and intensity studies. CONCLUSION The results suggested the efficacy of A. nilotica as potent antioxidant in S. cerevisiae system for the first time and can be used in neutraceuticals/therapeutics.