Assessment of single and combined effects of bisphenol-A and its analogue bisphenol-S on biochemical and histopathological responses of sea cucumber Holothuria poli.

Bisphenols (BPs) are among emerging pollutants that have been frequently detected in different compartments of marine ecosystems and elicited great concern due to their potential toxicity to marine organisms. This work aimed to investigate the toxicity of bisphenol A (BPA) and bisphenol S (BPS) on oxidative stress markers, neurotoxicity and histopathological alterations in sea cucumbers (Holothuria poli). The results showed that exposure to 200 μg/L of BPA and BPS produced oxidative stress, neurotoxicity in the digestive tract and respiratory tree, and several types of histopathological lesions in tissues of the respiratory tree of the sea cucumber, posing a health hazard to this aquatic organism. In addition, BPA has greater effects than BPS on the generation of oxidative stress marked by the inductions of catalase (CAT), glutathione S-transferase (GST) and malondialdehyde (MDA) levels and neurotoxicity shown by the decrease in acetylcholinesterase activity (AChE). The respiratory tree of sea cucumbers might be an appropriate tissue for assessing CAT, MDA and AChE activity levels, which are reliable biomarkers that may be useful in marine biomonitoring studies. Evaluation of histopathological lesions of the respiratory tree suggests that BPA and BPS and their mixture cause various tissue alterations that may be associated with oxidative stress damage and neurotoxicity. In conclusion, this study showed that oxidative stress (CAT and MDA) and neurotoxicity (AChE) markers, as well as respiratory tree lesions, are sensitive biomarkers for the assessment of BPA and BPS toxicity in sea cucumbers.