Potential of nature-derived compounds in mitigating toxicity of emerging contaminants: evaluation of cellular and physiological responses in sentinel organisms

The COVID-19 pandemic significantly increased the demand for detergents, cleaning products, and foaming agents for medical or industrial purposes to maintain hygiene and prevent microbial growth. These products contain several compounds in their formulations that can readily reach and threaten aquatic ecosystems. Among these are surfactants, recognized as common components in detergents because of their surface-active properties and are, also, classified as emerging contaminants. The most prevalent surfactant is sodium lauryl sulphate (SLS), an anionic detergent with antimicrobial properties, which is extensively used as a synthetic cleansing agent. Although SLS biodegradation ranges from 45% to 95% within 24 hours, its continuous introduction into the environment results in the maintenance of elevated levels in aquatic ecosystems. Anionic detergents, including SLS, exhibit a pronounced affinity for interacting with the lipids of cellular membranes and, at high concentrations, can lead to significant alterations. For this reason, the present investigation aimed to obtain novel insights into the potential mitigation of bergamot peel extract on cellular and physiological performances of Mytilus galloprovincialis exposed to SLS. Bioactive molecules were obtained by solvent extraction of bergamot peels, and the extract was then subjected to HPLC analysis for characterisation. Specimens were treated with SLS (0.01 mg L-1), bergamot peel extract (BRG: 5 mg L-1), and their mixture (SLS+BRG) for fourteen days. The immune response was assessed through the ability of haemocyte cells to perform phagocytosis, along with the gene expression of γ-actin, which plays a key role in the cytoskeleton rearrangement. The Neutral red retention assay and the Trypan blue exclusion test were employed to evaluate cytotoxicity on haemocytes and digestive gland (DG) cells. The physiological response was video-metrically assessed by cell volume regulation analysis (RVD assay) in DG cells, and the energy efficiency of organisms was assessed through byssus analysis. The expression of genes involved in antioxidant activity (Cu/ZnSOD, MnSOD, Hsp70, and CYP4Y1) was also evaluated. Results showed a consistent trend between the CTR and BRG groups, with significant differences compared to the SLS-treated groups. Meanwhile, the groups exposed to the combination (SLS+BRG) exhibited a recovery. These results support and provide novel insights into the potential of bergamot's bioactive compounds in mitigating pollutant-induced toxicity, proposing new alternatives to reduce the ecological impact of chemical pollutants in aquatic systems.