Decrease of activity of antioxidant enzymes, lysozyme content, and protein degradation in milk contaminated with heavy metals (cadmium and lead)

Abstract

The aim of this study was to evaluate the effect of added Cd and Pb to milk on its stability by determining antioxidant enzymatic activities, lysozyme content, and protein degradation. Antioxidant enzymatic activities were spectrophotometrically determined by superoxide dismutase, catalase, xanthine oxidase, and glutathione peroxidase assays; lysozyme was identified and quantified by HPLC-UV analysis, and protein degradation was investigated by spectrophotometric analysis of advanced oxidation protein products (AOPP) and dityrosine content. In this study, contaminated milk samples showed a significant reduction in activity of all studied enzymes compared with control milk. The contamination of milk also led to a significant reduction in the lysozyme content; lysozyme content was decreased about 22% and 18% in Pb milk and Cd milk, respectively, compared with control milk. The presence of the contaminants in the milk resulted in a significant increase of both dityrosine concentration and AOPP compared with the control milk. Moreover, between types of contaminated milk, dityrosine and AOPP values were significantly higher in the Pb milk than in the Cd milk. Therefore, it is important to monitor the presence of these toxic elements in milk for the damage they cause to consumer health both directly due to their ingestion and indirectly due to loss of milk stability.

Influence of Maternal Dietary Pattern on the Pro-Oxidant and Antioxidant Status of Mother’s Own Milk

“…Protein degradation, occurring indiscriminately, can reduce the quality of milk. However, due to the quantity ingested, it would hardly have repercussions that could be perceived in the short term (Grassi et al, 2022; Lorençoni et al, 2021; Ribeiro et al, 2023).…”

Occurrence and Consumer Health Risk Assessment of Heavy Metals in Frozen Demersal Fish and Cephalopod Products from Benoa Port, Bali Province

“…In contaminated environments, lead (Pb) and cadmium (Cd) are two heavy metals that are frequently found together. Both forms of heavy metals are commonly found in water habitats polluted by lead paint, car emissions, industrial pollution, and mine extraction byproducts (37). Ecotoxicological studies showed that Alburnus mossulensis fish that collect Cd in their bodies had hepatotoxic consequences, such as a decrease in total antioxidant capacity and an increase in oxidative damage to lipids and proteins (38).…”