Natural Bioactive Phytocompounds to Reduce Toxicity in Common Carp Cyprinus carpio: A Challenge to Environmental Risk Assessment of Nanomaterials

Nanomaterials, due to their large aspect-to-size ratio and reactive surfaces that facilitate their access through biological barriers, can induce oxidative stress in host cells. Therefore, there is a growing concern about the biological risks of nanomaterials. This study investigated the biological effects of copper (1.5 mg/L) as CuO or nanoparticles (Cu-NPs) in common carp Cyprinus carpio along with the beneficial effects of Myristiga fragrans seed extract (MFSE) administrated as post-treatment at different doses (4 or 8 or 12 mg/L) for 28 days. The MFSE exhibited a protective role by reducing in a dose-dependent manner the bioaccumulation of Cu level in CuO (from 2.46 to 1.03 µg/Kg in gills; from 2.44 to 1.06 µg/Kg in kidney) and Cu-NPs treated carps (from 2.44 to 1.23 µg/Kg in gills; from 2.47 to 1.09 µg/Kg in kidney) as well as modulating different blood parameters. A mitigation of the histological alterations induced by CuO and Cu-NPs exposure in carp gills (i.e., primary and secondary lamellar degeneration, lamellar fusion, necrosis) and kidneys (i.e., abnormal glomerulus, tubular injury, necrosis) was also observed after MFSE administration. The dietary supplementation of MFSE modulated also the antioxidant defense of carps with respect to the elevated levels of lipid peroxidation (LPO) and glutathione (GST) and the reduced catalase (CAT) induced by CuO and Cu-NPs. Overall, the CuO and Cu-NPs-induced toxicity in C. carpio was mitigated by using MFSE. Further studies are suggested to determine the optimum dose and delivery method of MFSE to guarantee a sustainable conservation of aquatic species.