Synthesis, Assessment of Biological Activity and Toxicity for N-(β-D-Glycopyranosyl)-Thiosemicarbazides

In the modern science, priority is given for the search of biological active compounds with specific properties. As a result of experimental data, it was found that in the reaction between N-(β-D-glycopyranosyl)-semicarbazide and the Lawesson reagent (2,4-bis(p-methoxyphenyl)-1,3-dithiadiphosphetane 2,4-disulfide) at the ratio 1:1 in pyridine when boiling under reflux in a water bath for 20 - 35 minutes, a new synthetic compound N-(β-D-glycopyranosyl)-thiosemicarbazide is formed. The individuality and structure of the target products were confirmed by 13C NMR spectroscopy, 1H NMR spectroscopy, IR spectroscopy, and elemental analysis. For the synthesized new compounds of N-(β-D-glycopyranosyl)-thiosemicarbazides, the probability of pharmacological and toxic effects were predicted by the computer method in silico. From the synthesized compounds N-(β-D-galactopyranosyl)-thiosemicarbazide, the probability of antibacterial (antibacterial) activity is predicted (Pa/Pi 0.544/0.013). The antibacterial activity of the compound (4) was confirmed in a test for salmonella infection of lambs, salmonellosis of calves, and colipathogenic E. coli serotypes. An experimental study by the in vitro method made it possible to conclude that the new synthetic compound N-(β-D-galactopyranosyl)-thiosemicarbazide in the studied concentrations has a pronounced bactericidal and bacteriostatic effect. The synthetic new compound N-(β-D-glyco- pyranosyl)-thiosemicarbazide is a promising compound for further study.


Introduction
In recent years, thiosemicarbazides have attracted more and more attention from researchers, based on which it is possible to form a variety of derivatives that are used in medicine as drugs with antimicrobial, anti-tuberculosis, antitumor, antifungal effects [1] [2].
It is widely known that carbohydrates can play a transport role in the body. Therefore, the search for ways to obtain new carbohydrate-containing derivatives of thiosemicarbazides is of fundamental importance for modern pharmacology. For this purpose, we carried out prospecting work on the selection of reaction conditions for obtaining carbohydrate-containing derivatives of thiosemicarbazides.
It is known that the Lawesson reagent was successfully used in the thionation of the carbonyl group of many classes of organic compounds [3] [4] [5]. However, the reaction of thionization of carbohydrate-containing semicarbazides using the Lawesson reagent to obtain thiosemicarbazides is still not sufficiently studied.
Our study aims to develop a new method for the synthesis of carbohydrate-containing derivatives of thiosemicarbazides based on the reactions of N-glycosylated semicarbazides when interacting with the Lawesson reagent and to study their biological properties. In particular, N-(β-D-xylopyranosyl)thiosemicarbazide and N-(β-D-galactopyranosyl)-thiosemicarbazide have been studied. To select from them the most promising compound exhibiting antibacterial properties, we preliminarily carried out computer analysis through the PASS program [6]; then the selected compound was tested in vivo and in vitro to confirm the predicted activities.

In Vitro Studies
Experiments on studying the antibacterial activity of N-(β-D-galactopyranosyl)thiosemicarbazide were carried out by the in Vitro method using standard bacteriological methods [7]. For this, by serial dilutions with distilled water (1:10;

Study of Acute Toxicity in Vivo
When searching for the most promising compounds for practical use, it is necessary to study the toxicology of newly synthesized compounds and the first necessary condition for the suitability of a compound is to determine the parameters of its acute toxicity. These indicators are necessary to establish the degree of hazard of a chemical, as well as for further research, where knowledge of the degree of acute toxicity is required.
The study of acute toxicity aims to determine the tolerable, toxic, and lethal doses of a pharmacological substance and the cause of death of animals.
Acute toxicity of pharmacological substances is determined by the following parameters: LD 0 is the maximum tolerated dose, LD 50 is the average lethal dose, LD 100 is the minimum lethal dose. LD 16 and LD 84 are also determined to establish the confidence limits of LD 50 is the average lethal dose. There are many classifications of chemicals for assessing acute toxicity [7]. To assess the toxicity of antiparasitic drugs, the classification according to [8] [9] is more suitable. Based on the foregoing, we studied the acute toxicity parameters of a new synthetic com- The experiments were carried out on 36 clinically healthy white mice of both sexes with a live weight of 18 -22 g. The substance was administered to the animals orally in the form of a 10% solution using a syringe equipped with a special metal probe, in various doses. Control animals received an appropriate volume of sodium chloride saline solution.
During the experiment, the animals were not limited to feeding and watering.
The experiments lasted 12 days, during which the general condition, the nature, International Journal of Organic Chemistry and degree of chemical toxicosis, the time of death of the experimental and control mice were observed. The corpses of the dead experimental animals were subjected to visual, as well as postmortem autopsy to establish the degree and nature of organ damage and the causes of death. Statistical processing of digital materials was carried out by the method [10], modified [11], using ordinary graph paper [12].

Prognosis of Biological Activities of Synthesized Compounds by PASS Program
Present an ordered list of the types of possible activities, indicating the probability of the presence of activity (Pa) and the probability of inactivity (Pi). From the data obtained, the types of activities were selected for which the Pa indicator is maximum, and the Pi indicator is minimum. In computer forecasting, the values of the probability of activity manifestation Pa ≥ 0.5 were taken into account. Table 1 shows the results of predicting 14 types of biological activity, as well as side toxic ef- Since we were interested in the antibacterial activity of the studied compounds, we focused on this activity. As can be seen (Table 1), of the two com-   Table 1 it can be seen that no toxic effect is predicted for compounds 3, 4. Therefore, for compound 4, an experimental assessment of the bacterial and bacteriostatic activity was carried out, and then the toxicity of this compound was also experimentally evaluated.

Results of in Vitro Experiments
The results of in vitro experiments carried out on a solid nutrient medium show ( Table 2) that N-(β-D-galactopyranosyl)-thiosemicarbazide exhibited bactericidal activity against the selected microbial cultures, although there was no pronounced species specificity in its action.
The bacteriostatic activity of the substance was studied by diluting it in meat-peptone broth at the same concentrations as in the previous experiment, followed by sowing pure cultures in it. The measurement results are shown in Table 3.
The results of this series of experiments showed ( Table 4) [14]. That is why N-(β-D-galactopyranosyl)thiosemicarbazide is a promising substance for its further study to use it in practice. Table 1 shows comparison of antimycobacterial, antituberculosic, anti-viral (influenza), antineoplastic activity (0.9 > Pa > 0.5) and with a low probability of cytostatic/cytotoxic, antidiabetic activity properties for N-(β-D-galactopyranosyl)thiosemicarbazide with the N-(β-D-xylopyranosyl)-thiosemicarbazide. Therefore, in addition to antibacterial activity, compound 4 possess high probability which can exhibit the above pharmacological properties, and is of interest as a promising drug for experimental studies.

Conclusions
An efficient method is proposed for the synthesis of carbohydrate derivatives of semicarbazides using the Lawesson reagent, which was not previously used for International Journal of Organic Chemistry Based on in silico analysis of the results, N-(β-D-galactopyranosyl)-thiosemicarbazide was selected from the two above-named compounds as the most promising antibacterial drug and with which experimental tests were carried out.
The results of in vitro (antibacterial activity) and in vivo (toxic effects) experiments allow us to conclude that the theoretical prediction of the antibacterial activity of N-(β-D-galactopyranosyl)-thiosemicarbazide confirmed by experimental data. Compound (4) in the studied concentrations has a pronounced bactericidal and bacteriostatic effect. It was also established that compound (4) belongs to the III class of hazardous substances; therefore, it can be concluded that N-(β-D-galactopyranosyl)-thiosemicarbazide is a promising compound for further study to use it in practice.