Effect of Silver Nanoparticles on Oxidative Stress, Tissues Alterations in the Rohu Labeo Rohita and Impact of Garlic Oil Allium Sativum and Cerium Oxide on the Antioxidant System of Challenged Fish

Large applications spectrum largely hangs on physicochemical and biological properties of silver nanoparticles (Ag-NPs) which vary with changing particles size. The unique properties of Ag-NPs are responsible for large uses in consumer‘s product and industry. Keeping in view the importance, Ag-NPs were grown through chemical and biological reduction. Formaldehyde was reducing agent in chemical route whereas, the lemon extract was in biological route. SEM images suggest agglomeration of small, grain like and spherical Ag-NPs in both routes. Particles were 16.59 nm mean size in chemical route 42.93 nm in biological route. Ranges of particles were 5-80 nm in chemical route and between 5-100 nm in biological method. The FT-IR spectra confirmed the particles were amine coated in chemical route. This study documented the proof of high profile of nutrients, minerals, total phenolic in garlic (40.80 ±2 .91 mg GAE/100 g) and flavonoid content (4.59 ± 1.28 mg RE/100 g). These components enable garlic to ameliorate a stress which is oxidative in nature. To record this capability, free radicals were emolyed including ABTS, FRAP and DPPH ABTS. Garlic exhibited significantly different scavenging of these radicals with values of starting from 35.22 ± 6.63 for FRAP, 28.82 ± 11.61 for DPPH and 231.64 ± 25.02 mg vitamin C equivalent for ABTS when determined per 100 g sample. In next study phase, effect on haematology, tissue alterations and oxidative stress posed by these particles were quantified. For this purpose, Labeo rohita (L. rohita) (50 ± 5 g weight, 29 ± 09 cm in length) was used. Six treatments were maintained in three replicates having 5 fishes in each replicate. First treatment was used as control and other five treatments were exposed to 10, 20, 30, 45 and 55 mgL-1 respectively for 28 days. Samples were randomly collected from each treatment on 7th, 14th and 28th day. Ag-NPs caused oxidative stress, significant haematological changes, gills and liver alterations. Liver and gill antioxidant system respond to elevated level of oxidative stress and changed the enzymatic level. Activity of CAT flucated at different concentrations and time intervals. Ag-NPs also stimulated production of SOD to increase the activity. The low dose also stimulated the synthesis and enhanced activity of GST in response to electrophilic toxic Ag-NPs. The malondialdehyde (MDA) content was slightly higher in liver compared to gill possibly due to involvement of liver in detoxification process. Elevated level of GSH showed that liver started defensive mechanism against the oxyraidcals. Ag-NPs also produced genotoxicity in test fish. This genotoxicity was assessed through comet and micronuclei assay. An increase in both comet and micronuclei was recorded in dose dependant manner which proved the genotoxicity of Ag-NPs. Elevated frequency of comet was recorded at 55 mgL-1 and same was in case of nuclear alterations (16.34 ± 2.71 %) and micronuclei (6.35 ± 1.34 %). The Ag-NPs also induced pathological changes in gills tissue and 10 mg L-1 Ag-NPs treatment induced fusion of secondary lamellae and separation of gill epithelium where treatment of 20 to 55 mg L-1 produced deformation, fusion and necrosis of lamellar cells, Hyperplasia, deformed cartilaginous skeleton, separation and lifting of epithelium, curling of lamellae. In liver, Ag-NPs created abnormality in hepatic tissues reducing the size of cells and nuclei. At lowest concentration, the hepatocytes began to swell where, higher concentrations accumulated condensed nuclear and pycnotic nuclei. The particles further caused cognitive enlargement of lysosomes, reduction in size of hepatocytes and stimulated production of necrotic and apoptotic bodies. In last part of study, ameliorated role of nano-ceria and garlic was determined against Ag-NPs induced toxicity. The Ag-NPs (25 mgL-1) and nano-ceria (50 μg kg-1) were given through water and prepared feed respectively. Results demonstrated that pre-treatment of nano-ceria recovered the L. rohita from Ag-NPs induce toxicity and oxidative stress. The nano-ceria pre-treatment actively restored the activity of GST, GSH CAT and SOD. It also reduced the level of lipid peroxidation. Further, pre-treatment also improved the haematological parameters, gill and liver tissue structure against Ag-NPs toxicity. Same was in case of garlic study. However, nano-ceria showed slightly higher ameliorated role compare to garlic. Further, garlic and nano-ceria showed better results of ameliorations in combined form compared to alone garlic and nano-ceria. This study concluded that, Ag-NPs induced toxicity and pre-treatment of nano-ceria and garlic recovered L. rohita from Ag-NPs induce toxicity and oxidative stress.