On the basis of biologically active 3-aminopyridin-2(1H)-ones, chemical modification of derivatives of the corresponding monothiooxamides, thiohydrazides, and conjugated 1,3,4-thiadiazole derivatives has been carried out for the first time.

This article reports on the synthesis of nine promising new 1,3,4-thiadiazole derivatives based on 3-aminopyridones, containing various acidic linkers. The synthesis was carried out by cyclizing the corresponding thiohydrazides 4a–c and anhydrides of glutaric, maleic, and phthalic acids upon heating in acetic acid solution. The conducted bio-screening of the synthesized new 1,3,4-thiadiazole derivatives containing different acidic linkers (butanoic, acrylic, and benzoic acids) showed that they have significant inhibitory activity against α-glucosidase (up to 95.0%), which is 1.9 times higher than the value for the reference drug acarbose (49.5%). Moreover, one of the 1,3,4-thiadiazole derivatives with a benzoic acid linker—2-(5-((6-Methyl-2-oxo-4-(thiophen-2-yl)-1,2-dihydropyridin-3-yl)carbamoyl)-1,3,4-thiadiazol-2-yl)benzoic acid (9′b)—showed an IC₅₀ value of 3.66 mM, nearly 3.7 times lower than that of acarbose (IC₅₀ = 13.88 mM). High inhibitory activity was also shown by 1,3,4-thiadiazole derivatives with a butanoic acid linker (compounds 7b, 7c)—with IC₅₀ values of 6.70 and 8.42 mM, respectively. A correlation between the structure of the compounds and their activity was also established. The results of molecular docking correlated well with the bioanalytical data. In particular, the presence of a butanoic acid linker and a benzoic fragment in compounds 7b, 7c, and 9b increased their binding affinity with selected target proteins compared to other derivatives 3–6 (a–c). Calculations according to Lipinski’s rule of five also showed that the synthesized compounds 7b, 7c, and 9b fully comply with Ro5 and meet all criteria for good permeability and acceptable oral bioavailability of potential drugs. These positive bioanalytical results will stimulate further in-depth studies, including in vivo models.

Reactions with allyl-, acetyl-, and phenylisothiocyanate have been studied on the basis of 3-amino-4,6-dimethylpyridine-2(1H)-one, 3-amino-4-phenylpyridine-2-one, and 3-amino-4-(thiophene-2-yl)pyridine-2(1H)-one (benzoyl-)isothiocyanates, and the corresponding thioureide derivatives 8-11a-c were obtained. Twelve thiourea derivatives were obtained and studied for their anti-diabetic activity against the enzyme α-glucosidase in comparison with the standard drug acarbose. The comparison drug acarbose inhibits the activity of α-glucosidase at a concentration of 15 mM by 46.1% (IC₅₀ for acarbose is 11.96 mM). According to the results of the conducted studies, it was shown that alkyl and phenyl thiourea derivatives 8,9a-c, in contrast to their acetyl–(benzoyl) derivatives and 10,11a-c, show high antidiabetic activity. Thus, 1-(4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)-3-phenylthiourea 9a has the highest inhibitory activity against the enzyme α-glucosidase, exceeding the activity of the comparison drug acarbose, which inhibits the activity of α-glucosidase by 56.6% at a concentration of 15 mm (IC₅₀ = 9,77 mM). 1-(6-methyl-2-oxo 4-(thiophen-2-yl)-1,2-dihydropyridin-3-yl)-3-phenylthiourea 9c has inhibitory activity against the enzyme α-glucosidase, comparable to the comparison drug acarbose, inhibiting the activity of α-glucosidase at a concentration of 15 mm per 41.2% (IC₅₀ = 12,94 mM). Compounds 8a, 8b, and 9b showed inhibitory activity against the enzyme α-glucosidase, with a lower activity compared to acarbose, inhibiting the activity of α-glucosidase at a concentration of 15 mM by 23.3%, 26.9%, and 35.2%, respectively. The IC₅₀ against α-glucosidase for compounds 8a, 8b, and 9b was found to be 16.64 mM, 19.79 mM, and 21.79 mM, respectively. The other compounds 8c, 10a, 10b, 10c, 11a, 11b, and 11c did not show inhibitory activity against α-glucosidase. Thus, the newly synthesized derivatives of thiourea based on 3-aminopyridine-2(1H)-ones are promising candidates for the further modification and study of their potential anti-diabetic activity. These positive bioanalytical results will stimulate further in-depth studies, including in vivo models.

The interaction results of 1,2-dibromo-3-isothiocyanatopropane with some pyrazoles as well as cytisine and salsoline alkaloids were presented in this paper. It was shown that the reaction resulted in one one-step and rather mild method for the preparation of the corresponding 1,3-thiazoline bromomethyl derivatives. The yield of this reaction was affected by the presence of a base and an order in which reagents were added. Molecular docking of the synthesized 1,3-thiazoline derivatives for putative antibacterial activity was carried out using the penicillin-binding target protein (PBP4) of the bacteria E. coli “Homo sapiens” and S. aureus “Homo sapiens” as an example. Molecular docking demonstrated that the compounds had insignificant binding energies at the level of selected reference drugs (Cephalotin and Chloramphenicol). The presence of natural alkaloids in the structure of thiazoline derivatives somewhat increased the affinity of these substrates for target proteins selected.

SrLnCuSe₃ (Ln = Dy, Ho, Er, Tm) compounds crystallize in the Pnma and Cmcm orthorhombic space group and belong to the Eu₂CuS₃ and KCuZrS₃ structural type, respectively. According to a single-crystal XRD study, the SrTmCuSe₃ unit cell parameters are a = 4.0631 (4), b = 13.4544 (14), c = 10.4430 (10) Å, and V = 570.88 (10) ų. All the studied SrLnCuSe₃ samples in the temperature range of 1.77–300 K demonstrate paramagnetic behavior without any features pointing to magnetic ordering. The measured Curie constants coincide with the values expected for Ln³⁺ ions with good accuracy, which confirms the stoichiometric composition of the samples and the non-magnetic state of the copper ions, Cu¹⁺ (S = 0). The conducted optical absorption study showed that the polycrystalline SrLnCuSe₃ (Ln = Dy, Ho, Er, Tm) samples are semiconductors with a direct bandgap ranging from 2.14 eV to 2.31 eV. Two indirect bandgaps were revealed and explained by the presence of optical transitions to highly dispersive subbands in the conduction band. The compounds demonstrate two reversible phase transitions α⇆β, β⇆γ and an incongruent melting at 1606 K (Dy), 1584 K (Ho), 1634 K (Er), and 1620 K (Tm) associated with the formation of solid solutions of SrSe, Cu_2-XSe, and Ln₂Se₃ binary compounds.

On the basis of 4-(thien-2-yl)-3-aminopyridine-2(1 H )-one, the corresponding chloroacetamide and condensed 1 H -pyrido[2,3 -b ][1,4]oxazine-2(3H)-one were synthesized by the reaction of acylation with chloroacetyl chloride. Thioureide derivatives of 3-aminopyridine-2(1 H )-one were obtained by reactions with a number of isothiocyanates. It was shown that the carbamothionylmethacrylamide derivative cyclizes rather easily into substituted 1,3-thiazine. Molecular docking of synthesized derivatives for antithrombotic activity was carried out, which showed that the presence of a thiourea fragment in the pyridone core leads to an increase in affinity for the selected protein. The hemorheological study of the compounds using the in vitro model of the increased blood viscosity syndrome also showed activity at the level of the reference drug pentoxifylline.