RESUMO
While food additives are widely used in the modern food industry and generally are important in maintaining the ability to provide food for the increasing world population, the progress occurring in this field is much ahead of the evaluation of their possible consequences for human health. The present study suggests a set of single- and multi-enzyme assay systems for revealing toxic effects of the most widely spread food preservatives, such as sorbic acid (E200), potassium sorbate (E202), and sodium benzoate (E211) at the primary molecular level of their interaction with enzymes. The assay is based on the inhibition of enzyme activity by toxic substances proportional to the amount of the toxicants in the sample. The single-enzyme assay system based on NAD(P)H:FMN oxidoreductase (Red) proved to be most sensitive to the impact of food additives, with the IC50 values being 29, 14, and 0.02 mg/L for sodium benzoate, potassium sorbate, and sorbic acid, respectively, which is considerably lower than their acceptable daily intake (ADI). No reliable change in the degree of inhibition of the enzyme assay systems by food preservatives was observed upon elongating the series of coupled redox reactions. However, the inhibition of activity of the multi-enzyme systems by 50% was found at a preservative concentration below the maximum permissible level for food. The inhibition effect of food preservatives on the activity of butyrylcholinesterase (BChE), lactate dehydrogenase (LDH), and alcohol dehydrogenase (ADH) was either absent or found in the presence of food preservatives at concentrations significantly exceeding their ADI. Among the preservatives under study, sodium benzoate is considered to be the safest in terms of the inhibiting effect on the enzyme activity. The results show that the negative effect of the food preservatives at the molecular level of organization of living things is highly pronounced, while at the organismal level it may not be obvious.