Ecotoxicological evaluation of the UV-filter octocrylene (OC) in embryonic zebrafish (Danio rerio): Developmental, biochemical and cellular biomarkers

Octocrylene (OC), an UV-filter (OUVF) is used in many cosmetic products to protect the skin against the harmful effects of UV radiation. Octocrylene has been detected in the environment and become an emerging contaminant of concern. However, the eco-toxicological data on octocrylene and their molecular effects and mechanism of action on freshwater fish are very limited. In this research work, the potential toxicity of octocrylene and its mechanisms on morphology, antioxidant and AChE activity, apoptosis, and histopathological changes were investigated in embryonic zebrafish (Danio rerio) at different concentrations (5, 50 and 500 μg/L). Embryos/larvae (96 hpf) treated with 50 and 500 μg/L of OC caused developmental abnormalities, and decreased hatching rate and heartbeat rate. The oxidative damage (LPO) and antioxidant enzyme (SOD, CAT and GST) activities were apparently elevated (P < 0.05) at the highest test concentration (500 μg/L). However, acetylcholinesterase (AChE) activity was significantly inhibited at the highest test concentration. Also, CP induced apoptosis in a dose-dependent manner. The zebrafish exposed to 50 and 500 μg/L showed histopathological changes including elongated yolk sac, swim bladder inflammation, muscle cell degeneration, retinal damage and pyknotic cells. In conclusion, octocrylene has induced oxidative stress at environmentally relevant concentrations leading to developmental toxicity, neurotoxicity, and histopathological damage in zebrafish embryos/larvae.

Efficiency of hematological, enzymological and oxidative stress biomarkers of Cyprinus carpio to an emerging organic compound (alphamethrin) toxicity

Alphamethrin is one of the extensively used pyrethroids. Its non-specific mode-of-action might affect the non-target-organisms. Its toxicity data on aquatic organisms are lacking. We determined the toxicity (35 days) of alphamethrin (0.6µg/L and 1.2µg/L) on non-target-organisms by evaluating the efficiency of hematological, enzymological and antioxidants biomarkers of Cyprinus carpio. Compared with the control group, the efficiency of the biomarkers studied was significantly (p<0.05) impaired in the alphamethrin groups. Alphamethrin-toxicity altered hematology, transaminases and the potency of LDH of fish. ACP and ALP activity and biomarkers of oxidative stress in the gills, liver and muscle tissues were affected. IBRv2 index reveals that the biomarkers were inhibited. The observed impairments were the toxicity effects of alphamethrin with respect to concentration and time. The effectiveness of biomarkers for alphamethrin toxicity was like the toxicity data available on other banned insecticides. Alphamethrin could cause multiorgan toxicity on aquatic organisms at µg/L level.

A study to assess the health effects of an anticancer drug (cyclophosphamide) in zebrafish (Danio rerio): eco-toxicity of emerging contaminants

Cyclophosphamide (CP) is widely used for treating various kinds of cancer. Because of its high intake, metabolism and excretion, these anticancer medications have been detected in the aquatic environment. There is very limited data on the toxicity and effects of CP on aquatic organisms. The present study aims to assess the toxic effect of CP on certain oxidative stress biomarkers (superoxide dismutase-SOD, catalase-CAT, glutathione peroxidase-GPx, glutathione-GSH, glutathione S-transferases-GST and lipid peroxidation-LPO), protein, glucose, metabolising enzymes (aspartate aminotransferase-AST, alanine aminotransferase-ALT), and ion-regulatory markers (sodium ions-Na⁺, potassium ions-K⁺, and chloride ions-Cl^-), and histology in the gills and liver of Danio rerio at environmentally relevant concentrations (10, 100 and 1000 ng L^-1). Exposure to CP for 42 days led to a significant decrease in SOD, CAT, GST, GPx and GSH levels in the gills and liver tissues of zebrafish. The level of lipid peroxidation in the gills and liver tissues of zebrafish was significantly increased compared to the control group. Chronic exposure significantly changes protein, glucose, AST, ALT, Na⁺, K⁺ and Cl^- biomarkers. Fish exposed to different levels of CP showed necrosis, inflammation, degeneration and hemorrhage in the gills and hepatic tissues. The observed changes in the studied tissue biomarkers were proportional to both dose and time. In conclusion, CP at environmentally relevant concentrations causes oxidative stress, energy demand, homeostasis disturbances, and enzyme and histological alterations in the vital tissues of zebrafish. These alterations were similar to the toxic effects reported in mammalian models.