The potential role of photobiotic in enhancing liver antioxidant status as determined by enzyme scavenging activity and molecular mechanisms in Gilthead seabream (Sparus aurata) teleost

Oxidative stress is one of the intensive aquaculture implications, especially in fish fed high dietary lipids. The use of natural plants as a source of antioxidant substances in the aquatic diet is an alternative natural-based solution to overcome. The present study aims to investigate the potential effects of Moringa olifera leave meal (MLM) on antioxidant status in the liver of Gilthead seabream (Sparus aurata) as determined by antioxidant enzyme activities (CAT, SOD and GR), antioxidant gene expression (CAT, CuZn-SOD, and GR), and regulatory pathway genes (nrf2, nkef-A, and nkef-B). S. aurata specimens (138.75 g) were divided into 4 groups in duplicate and fed MLM at increasing levels of 5, 10, and 15% at a daily feeding rate of 1.5%. Liver samples were collected after 15 and 30 days of intervention. The obtained findings revealed that dietary MLM significantly enhanced the liver activities of SOD and GR enzymes compared to the control group after 15 days of treatment, and the effect continued after 30 days. However, the catalase enzyme remains unaffected throughout the experiment. The gene expression of CuZn-SOD was significantly upregulated after 15 and 30 days of MOL intervention. However, the significant increase of GR gene expression was reported after 15 days only. CAT gene expression tended to increase with dietary MOL. The regulatory gene expression, including nrf2, nkef-A, and nkef-B were significantly upregulated with dietary MOL at levels of 5-10%. In conclusion, the dietary intervention of MOL could enhance liver antioxidant status at both biochemical and molecular levels, and the possible mechanism is enhancing nrf2 pathways as antioxidant regulatory genes.