The dissertation is devoted to a comprehensive investigation of the biological properties of synthetic thiosulfonic acid esters, with particular emphasis on their antimicrobial, fungicidal, radical-scavenging, and antioxidant activities, as well as their effects on selected pathways of protein and lipid metabolism, the intensity of lipid peroxidation, and the functional status of the antioxidant defense system in the blood and tissues of laboratory animals. The relevance of this study is обусловed by the need to identify novel highly effective, low-toxicity biologically active compounds that can be applied as antimicrobial agents, antioxidants, and regulators of metabolic processes in animal husbandry and veterinary medicine.
The in vitro study evaluated the fungicidal and bactericidal activities of S-methyl 4-aminobenzenethiosulfonate, S-ethyl 4-aminobenzenethiosulfonate, S-allyl 4-aminobenzenethiosulfonate, S-propyl 4-aminobenzenethiosulfonate, and S-allyl 4-acetylaminobenzenethiosulfonate against the reference strains Escherichia coli, Staphylococcus aureus, Mycobacterium luteum, Candida tenuis, and Aspergillus niger. S-Ethyl 4-aminobenzenethiosulfonate (ETS), S-allyl 4-aminobenzenethiosulfonate (ATS), and S-allyl 4-acetylaminobenzenethiosulfonate (AATS) exhibited the highest antimicrobial activity. The minimum inhibitory and bactericidal concentrations of these compounds were determined, confirming their potential as promising antimicrobial agents. Furthermore, ATS, AATS, and ETS demonstrated the strongest radical-scavenging and antioxidant activities, providing the rationale for subsequent investigations of their biological effects in vivo.
The in vivo experiments were conducted on white Wistar laboratory rats in accordance with internationally accepted bioethical standards. ETS, ATS, and AATS were administered at doses of 100 and 50 mg/kg body weight. Subsequently, the parameters of the antioxidant defense system, as well as protein and lipid metabolism in blood and tissues, were evaluated.
The biological effects of the investigated thiosulfonates were found to depend on both their chemical structure and the administered dose. Administration of ETS at 100 mg/kg improved the antioxidant profile of blood, whereas the 50 mg/kg dose resulted in a more pronounced activation of antioxidant enzymes in the blood, kidneys, liver, brain, and skeletal muscles. Similarly, ATS and AATS induced dose-dependent changes in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and in the content of reduced glutathione, indicating their ability to effectively regulate the prooxidant–antioxidant balance in the organism.
It was demonstrated that the investigated S-esters of thiosulfonic acids also influence lipid and protein metabolism. Their administration reduced the concentrations of total lipids, triacylglycerols, and esterified cholesterol, indicating a hypolipidemic effect. The most pronounced effect of AATS was observed at a dose of 100 mg/kg, whereas ETS and ATS were more effective at 50 mg/kg. In addition, ETS and ATS administered at 100 mg/kg positively affected the protein-synthesizing function of the liver, as evidenced by increased total protein concentration, a higher albumin-to-globulin ratio, and reduced blood urea concentration.
The scientific novelty of the study lies in establishing the dose-dependent effects of S-ethyl 4-aminobenzenethiosulfonate, S-allyl 4-aminobenzenethiosulfonate, and S-allyl 4-acetylaminobenzenethiosulfonate on antioxidant defense, as well as protein and lipid metabolism in animals. It was demonstrated for the first time that ATS possesses the highest radical-scavenging activity, while all investigated S-esters of thiosulfonic acids effectively regulate the prooxidant/antioxidant defense system and individual metabolic pathways depending on the administered dose.
The practical significance of the obtained results lies in the potential application of S-esters of thiosulfonic acids as promising antimicrobial and antioxidant agents for protecting animal feeds against pathogenic microorganisms during production and storage, as well as a basis for developing novel preparations capable of regulating metabolic processes in animals. The research findings have been implemented in the educational process and research activities of the National University "Lviv Polytechnic".
