Antioxidant Potential of Schistocerca gregaria (Orthoptera: Acrididae) Extract: HPLC Analysis, Molecular Docking, and Bioassays.

Insects are emerging as a sustainable source of natural products in alternative and complementary medicine. This study evaluated the in vitro antioxidant activity and cytotoxic effects of methanolic extract of Schistocerca gregaria. Antioxidant activity was evaluated in the second, third, fourth, and fifth nymphal instars of S. gregaria. The results revealed that fifth nymphal instar exhibited markedly higher antioxidant capacity than the earlier instars with IC50 of 27.73, 74.71, and 34.32 µg/mL in the DPPH radical scavenging assay, FRAP and ABTS system, respectively for fifth nymphal instar of S. gregaria. Further characterization of the fifth nymphal instar methanolic extract was accomplished through HPLC leading to the identification of phenolic acids (chlorogenic, caffeic, and Ferulic acids), flavonoids (quercetin, apigenin, and kaempferol) with quercetin, apigenin, and chlorogenic as dominant constituents. Molecular docking study was performed to corroborate the in vitro results. Cytotoxicity testing on normal human skin fibroblasts indicated that the methanolic extract of the fifth nymphal stage was nontoxic up to 1000 µg/mL. No toxicity or mortality was observed at doses up to 4000 mg/kg.bw in zebrafish and 1500 mg/kg in mice. These findings confirm the antioxidant potential of S. gregaria nymphal extract with no in vitro or in vivo toxicity.