Design and synthesis of pyrido[2,1-b][1,3,5]thiadiazine library via uncatalyzed Mannich-type reaction

The Reactions of N,N'-Diphenyldithiomalondiamide with Arylmethylidene Meldrum's Acids

The Michael addition reaction between dithiomalondianilide (N,N'-diphenyldithiomalondiamide) and arylmethylidene Meldrum's acids, accompanied by subsequent heterocyclization, was investigated along with factors affecting the mixture composition of the obtained products. The plausible mechanism includes the formation of stable Michael adducts which, under the studied conditions, undergo further transformations to yield corresponding N-methylmorpholinium 4-aryl-6-oxo-3-(N-phenylthio-carbamoyl)-1,4,5,6-tetrahydropyridin-2-thiolates and their oxidation derivatives, 4,5-dihydro-3H-[1,2]dithiolo[3,4-b]pyridin-6(7H)-ones. The structure of one such product, N-methylmorpholinium 2,2-dimethyl-5-(1-(2-nitrophenyl)-3-(phenylamino)-2-(N-phenylthiocarbamoyl)-3-thioxopropyl)-4-oxo-4H-1,3-dioxin-6-olate, was confirmed via X-ray crystallography.

Studying the adaptogenic activity of a series of tetrahydropyrido[2,1-b] [1,3,5] thiadiazine derivatives

Introduction. In the modern world people are exposed to the influence of adverse psychological and physical factors, escalating in intensity. The search for new pharmacodynamic effects of [1,3,5]-thiadiazine derivatives designated by significant biological activity of these compounds is an essential issue.

Aim. To research adaptogenic activity of tetrahydropyrido[2,1-b][1,3,5]thiadiazine derivatives using a modified Porsolt Forced Swim Test.

Materials and methods. Four substances from the group of 3-R-8-aryl-6-oxo-3,4,7,8-tetrahydro-2H,6Hpyrido[2,1-b][1,3,5]thiadiazine-9-carbonitriles were selected for the research. Rats were divided into a control group, 5 reference groups (amitriptyline, caffeine, thiotriazolin, thiocetam, ginseng) and 4 experimental groups according to the number of the studied original tetrahydropyrido[2,1-b][1,3,5] thiadiazine derivatives.

Results. Intragastric injection of substance 2 for 5 days in the modified forced swim test (forced swimming with freight) increased work capacity and endurance of the rats by 103.42% as opposed to the initial results. The detected adaptogenic activity of this tetrahydropyrido[2,1-b][1,3,5]thiadiazine derivative six times exceeds adaptogenic activity of ginseng and seven times that of amitriptyline. The rats in the control group were active for a bit longer time. Ginseng raised the time of activity by 17% at day 5. Caffeine essentially reduced work capacity and endurance. Amitriptyline showed adaptogenic activity at day 3 of the research (increase by 10.4%). Thiotriazolin also showed adaptogenic activity on day 3 of the research (increase by 30.17%). Thiocetam increased the time of activity by 78.55%. Substance 4 had adaptogenic activity too; it increased the time of activity in aversive conditions by 58.25%, which three times exceeds this parameter for ginseng and four times for amitriptyline. 

The effect of derivatives of tetrahydropyrido[2,1-b][1,3,5] thiadiazine on hematologic indices of rats with subacute parotitis

Introduction: Regardless of belonging of NSAIDs to one or another chemical group, they all have common side effects that can occur when using these drugs for a long or short period. One type of toxicity in the spectrum of side effects of modern non-steroidal anti-inflammatory drugs is hematotoxicity.

Objectives: to study the indices characterizing the red and white hematopoiesis in a clinical blood examination in animals with a simulated inflammation process against a background of pharmacocorrection with original thiadiazine derivatives.

Methods: The experiments were carried out on 48 white pedigree mature rats of both sexes weighing 170–210 g. The tetrahydropyrido [2,1-b] [1,3,5] thiadiazine derivatives II, III and V were selected, since they showed the strongest anti-inflammatory, analgesic and antipyretic properties in the previous experiments. The animals were divided into eight groups: intact (rats without the pathology), control (with inlammation), referent 1 (inflammation+diclofenac sodium 0.5 mg/kg), referent 2 (inflammation+analgin 5 mg/kg), referent 3 (inflammation+indomethacin 5 mg / kg) and three test groups (with test substances administered at a dose of 5 mg/kg). Administration of the drugs was carried out for 14 days at the above doses. The standard methods were used to determine the number of erythrocytes, hemoglobin, color index, ESR, leukocytes and neutrophils.

Results: In the analysis of the numerical results of the experiment, the valid ranges of values were determined for most parameters under study, which made it possible to use nonparametric statistical methods, including the Wilcoxon signed-rank test, to evaluate the reliability of differences. The use of tetrahydropyrido [2,1-b] [1,3,5] thiadiazine derivatives II, III, V in animals with experimental parotitis was accompanied by an increase in the number of erythrocytes in comparison with that in the control group.

Conclusion: The studies of three derivatives of tetrahydropyrido [2.1-b] [1.3.5] thiadiazine, which have a high anti-inflammatory activity, proved that the compounds III and V have no hematotoxicity.

Recent developments in multicomponent synthesis of structurally diversified tetrahydropyridines

Tetrahydropyridines (THPDs) have recognized as a major constituent of naturally occurring alkaloids and exhibits various biological and pharmacological profiles. For their synthesis, MCRs are employed as an excellent tool to generate vast libraries.