Brown algae (Cystoseira myrica) promotes antioxidant biochemical and molecular responses in oxidative-stressed Drosophila melanogaster model

Background Oxidative stress has been linked to many life-threatening diseases. Therefore, exploring new drugs to mitigate oxidative stress has been the top priority in recent years. Drosophila melanogaster was used as a model organism to assess the antioxidant activity of the aqueous extract of brown algae, Cystoseira myrica. Methods The extract was subjected to a scavenging activity test and gas chromatography-mass spectrometry (GC-MS) analysis. Molecular docking was also performed to predict the affinity of active constituents to glutathione S-transferase and thioredoxin enzymes. Oxidative stress was induced in flies with H₂O₂ for 5 days, alongside controls. Treatments with low and high extract concentrations continued for another 5 days in stressed flies. Fly survival, antioxidant markers, and expressions of relevant genes were quantified. Our results indicate that the aqueous extract of C. myrica exhibited a good scavenging activity, presumably due to the detected compounds with antioxidant activity, such as squalene, anhydronectryachrysone, methoxy-substituted aromatic metabolites, penrtadecanoic, hexadecanoic (palmitic acid), and octadecadienoic derivatives, and quinone-related compounds. Molecular docking demonstrated that 2,3,7-trimethoxy-8,9-(methylenedioxy)-N-methyl-pavinan, 7,10-octadecadienoic acid methyl ester, and hexadecanoic acid have the best affinity for Drosophila GST and thioredoxin. Oxidative stress was evident in Drosophila exposed to H₂O₂, with low levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GSR), and high levels of nitric oxide (NO) and malondialdehyde (MDA). Moreover, glutathione S-transferase (GST) and heat shock protein ( HSP ) genes were upregulated, resulting in lower survival compared to the control. Following treatment with C. myrica extract, most markers improved, as did survivorship. Conclusion The results indicated that feeding on the aqueous extract of C. myrica rebalanced the induced oxidative stress and improved survival.