Novel N3 substituted derivatives of 4-iminothiazolidine-2-one were synthesised under the reactions of [2+3]cyclocondensation, thionation and aminolysis. The functionalisation of 3-phenyl-4-imino-thiazolydine-2-one was carried out in its C5 position under condensation Knoevenagel and nitrosation reactions. The antioxidant activity of the synthesised compounds was evaluated in vitro by the method of their scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. When compared with existing antioxidants, some of our compounds were found to be more potent.

Synthesis of novel N3 and C5 substituted thiazolo[4,5-b]pyridin-2-ones was carried out on the basis of [3+3]-cyclocodensation, acylation and alkylation reactions. The structures of the obtained compounds were confirmed by 1H NMR spectroscopy, and elemental analysis. The anti-inflammatory action of novel thiazolo[4,5-b]pyridine-2-one derivatives was evaluated in vivo employing the carrageenan-induced rat paw edema method. When compared with Ibuprofen, some our compounds were found to be more potent. Graphical abstract

The problem of finding effective low-toxic anticancer agents is one of the most important in modern medicine and pharmacy. Despite a large selection of anticancer drugs and a variety of mechanisms of their action, the effectiveness of existing drugs continues to be insufficient. Among the numerous natural and synthetic heterocyclic compounds that exhibit anticancer activity, 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine derivatives, which are able to initiate different pathways of tumor cell death. Based on this, the synthesis of new derivatives of this class of compounds and the study of their anticancer properties is relevant. The aim of the work is to synthesis of new 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines and study their anticancer activity. Materials and methods. It was used methods of organic synthesis, physical and chemical methods of analysis organic compounds (1H NMR spectroscopy, elemental analysis). Results. In order to obtain new 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines, the interaction implemented of 4-amino-4H-[1,2,4]triazole-3-thiols with the corresponding bromoacetophenones. The reaction proceeds by heating the above reagents in alcohol with the closure of the thiadiazine ring and the formation of 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine systems. The structure of all synthesized compounds was confirmed by 1H NMR spectroscopy and elemental analysis data. The study of the anticancer activity of the synthesized compounds was carried out in the framework of the international scientific program DTP (Developmental Therapeutics Program) of the National Cancer Institute (NCI, Bethesda, Maryland, USA). It was found that the synthesized compounds exhibited different levels of anticancer activity. The most active among the tested substances was compound 3j with an average GP value of 28.73. The most sensitive to it were the lines of melanoma MDA-MB-435 and SK-MEL-2, kidney cancer A498 and RXF 393, CNS cancer SNB-75, and non-small cell lung cancer NCI-H522. The secondary stage of studies of this compound confirmed its high anticancer activity against most cancer cell lines. Conclusions. As a result of the interaction of 4-amino-4H-[1,2,4]triazole-3-thiols with the relevant bromoacetophenones, a series of new triazolo[3,4-b][1,3,4]thiadiazines was not described in the literature was synthesized. Testing the synthesized compounds for the antitumor activity made it possible to isolate 1 highly active compound with a pronounced anticancer effect, which in terms of activity approaches or exceeds the known drugs 5-fluorouracil (5-FU) and cisplatin, as well as an anticancer agent, curcumin.

In this review we systematized the theoretical and experimental data concerning the versatile approaches for the synthesis of N-acylphenothiazines. The aim of the study was to compile the literature reported worldwide in the past 20 years. This article also reviewed the analysis of pharmacological activities of these heterocycles as one of the promising chemotherapeutic objects for the modern bioorganic and medicinal chemistry. It has been hypothesized that the enormous biological potential of these moieties is due to the radical nature in the acyl moiety. Therefore, the present review will be a good contribution to the literature and will provide the platform for the medicinal chemistry researchers to carry out more studies aiming the N-acylphenothiazine moieties as the novel chemotherapeutic agents.

A series of some new pyrazole-substituted 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines was synthesized in this study. The structures of target substances were confirmed by using 1H and 13С NMR spectroscopy, mass spectrometry and elemental analysis. The synthesized compounds have been evaluated for antimicrobial activity against five bacterial strains (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus) and two fungal strains (Candida albicans and Cryptococcus neoformans). The antimicrobial screening studies of synthesized substances established that 2 of 12 compounds show pronounced antibacterial activity against the strain Staphylococcus aureus.