Synthesis, in vitro urease inhibitory activity and molecular docking of 3,5‐disubstituted thiadiazine‐2‐thiones

Thiadiazine-thiones as inhibitors of leishmania pteridine reductase (PTR1) target: investigations and in silico approach

Leishmaniasis is a widespread parasitic disease and is one of the major public health concerns in developing countries. Many drugs have been identified for leishmania as targets, but the potential toxicity and long-term treatment remain the most significant problems in terms of further development. The present study employed physicochemical investigations, structure-based virtual screening, ADMET analysis, molecular dynamics simulation, and MM-PBSA, to identify potential compounds for Leishmania. We evaluated 30,926 natural products from the NPASS database, and four potentials passed the pharmacokinetic ADMET studies and were verified using the molecular docking approach. Molecular docking results showed good binding interaction of the compounds with the active site of leishmania pteridine reductase enzyme PTR1, with compound TTC1 showing FRED and Autodock binding energies of -10.33 and -10.94, respectively, which were comparable with the antileishmania drugs of Allopurinol, Miltefosine and the original ligand, methotrexate. TTC1 compound was found to be favorable for hydrophobic interaction with PTR1. In addition, the physicochemical properties of the compounds were studied using the SwissADME web server. All compounds followed Lipinski's rule of five and can be considered as good oral candidates. The analysis of the 100 ns molecular dynamics simulation results based on the best-docked TTC1 with PTR1 receptor demonstrates stable interactions, and the complex undergoes low conformational fluctuations. The average of the calculated binding free energy of the TTC1-1e7w complex is (-68.67 kJ/mol), and the result demonstrated that the TTC1 promoted stability to the Leishmania-PTR1 complex. The potential compounds can be further explored for their antileishmanial activity.Communicated by Ramaswamy H. Sarma.

Thiadiazine thione derivatives as anti-leishmanial agents: synthesis, biological evaluation, structure activity relationship, ADMET, molecular docking and molecular dynamics simulation studies

During last decades, 3,5-disubstituted-tetrahydro-2H-thiadiazine-2-thione scaffold remains the center of interest due to their ease of preparation, diverse range substituents at N-3 and N-5 positions, and profound biological activities. In the current study, a series of 3,5-disubstituted-tetrahydro-2H-thiadiazine-2-thiones were synthesized in good to excellent yield, and the structure of the compounds were confirmed by various spectroscopic techniques such as FTIR, 1H-NMR, 13C-NMR and Mass spectrometry, and finally evaluated against Leishmania major. Whereas, all the evaluated compounds (1-33), demonstrate potential leishmanicidal activities with IC50 values in the range of (1.30- 149.98 uM). Among the evaluated compounds such as 3, 4, 6, and 10 exhibited excellent leishmanicidal activities with IC50 values of (2.17 μM), (2.39 μM), (2.00 μM), and (1.39 μM), respectively even better than the standard amphotericin B (IC50 = 0.50) and pentamidine (IC50 = 7.52). In order to investigate binding interaction of the most active compounds, molecular docking study was conducted with Leishmania major. Further molecular dynamic simulation study was also carried out to assess the stability and correct binding of the most active compound 10, within active site of the Leishamania major. Likewise, the physiochemical properties, drug likeness, and ADMET of the most active compounds were investigated, it was found that none of the compounds violate Lipiniski's rule of five, which show that this class of compounds had enough potential to be used as drug candidate in near future.Communicated by Ramaswamy H. Sarma.

One pot synthesis of 5-hydroxyalkylated thiadiazine thiones: Implication in pain management and bactericidal properties

The synthesis of a new series of thiadiazine thiones including 5-(2-hydroxyethyl)-3-alkyl/aryl-1, 3, 5-thiadiazine-2-thiones (1-5), 5-(2-hydroxypropyl)-3-alkyl/aryl-1, 3, 5-thiadiazine-2-thiones (6-8), 3,5-dipropyl-1, 3, 5-thiadiazine-2-thione (9) and (2-(5-alkyl/aryl-6-thioxo-1, 3, 5-thiadiazine-3-yl) alkyl acetate/benzoate) (10-17) was accomplished via one pot reaction. The structures of the synthesized compounds were characterized through NMR and Mass spectrometry. The anti-nociceptive activity of compounds was performed on BALB/C mice by hot plate method, where compounds 3, 5 (50 μg/kg), and 8 (50, 100 μg/kg) exhibited significant effect (P < 0.01, P < 0.05) in latency time of 15, 30, and 60 min, while compounds 6 and 16 (100 μg/kg) exhibited significant effect (P < 0.01, P < 0.05) in latency time interval of 15 and 30 min. Compounds 1, 12-13, and 15 showed moderate activity. Among the tested hits, compounds 5 (17.3 ± 2.2), 11 (16.2 ± 2.1), and 8 (16.1 ± 2.1) showed significant anti-nociceptive potential. Molecular docking studies on the most active anti-nociceptive hits indicated that the activity might be attributed to the ability of the compounds to target μ-opioid receptor (μOR) effectively. Furthermore, compounds 14 and 11 showed anti-bacterial activity against Pseudomonas aeruginosa and MSRA with MIC of 40.97 and 54.77 μg/mL, respectively. In addition, the predicted ADMET profile of 5, 9, and 11 indicates that these molecules follow the drug-likeness criteria, and their activity can be enhanced through structural optimization.

Carbene-Catalyzed Atroposelective Annulation for Quick Access to Axially Chiral Thiazine Derivatives

An N-heterocyclic carbene (NHC)-catalyzed atroposelective annulation reaction is disclosed for quick and efficient access to thiazine derivatives. A series of axially chiral thiazine derivatives bearing various substituents and substitution patterns were produced in moderate to high yields with moderate to excellent optical purities. Preliminary studies revealed that some of our products exhibit promising antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo) that causes rice bacterial blight.

Analagesic and Anti-Inflammatory Potentials of a Less Ulcerogenic Thiadiazinethione Derivative in Animal Models: Biochemical and Histochemical Correlates

Purpose

Gastric ulcer induced by NSAIDs is the major medical concern and researchers are utilizing several approaches to combat this medical issue. In the current study, we investigated the efficacy of thiadiazinethione derivative (2,2’(2-thioxo-1,3,5-thiadiazinane-3,5-diyl) diacetic acid, as new less ulcerogenic compound.

Methods

2,2’(2-thioxo-1,3,5-thiadiazinane-3,5-diyl) diacetic acid was evaluated using standard animal models including hot plate, writhing test and formalin induced nociceptive models. Anti-inflammatory activity was assessed via carrageenan-induced paw oedema model. Involvement of opioidergic nociceptive mechanism was confirmed via naloxone administration in hot plat assay. The gastro-ulcerogenic potential of test and standard compounds were evaluated via NSAID-induced pyloric ligation model followed by standard histopathological and biochemical analysis.

Results

In acetic acid-induced writhing test, our compound significantly reduced abdominal constrictions at the tested doses of 15 (p < 0.05), 30 (p < 0.01) and 45 mg kg⁻¹ (p < 0.001) as compared to control (p < 0.001). In hot plate test, after 30 min of administration, our test compound showed significant anti-nociceptive potential (p < 0.05 at 15 and 30 mg kg⁻¹ and p < 0.01 at 45 mg kg⁻¹) and tramadol (p ˂ 0.001) at 30 mg kg⁻¹ dose. After 60 min tramadol (30 kg⁻¹) and test sample (30, 45 mg kg⁻¹) exhibited significant anti-nociceptive activity p < 0.001. In Formalin-induced nociceptive response, a significant decline (p ˂ 0.001) was observed for aspirin and test compound during acute and chronic phases. Decline in the anti-nociceptive potential of tramadol and test sample via administration of naloxone indicate the involvement of opioidergic mechanism. Our compound exhibited significant anti-inflammatory activity in second phase of carrageenan induced paw oedema model. Histological and biochemical parameters exhibited less ulcerogenic potential as compared to aspirin.

Conclusion

Our findings suggests that our test compound has desirable anti-nociceptive and anti-inflammatory potentials with less propensity to cause gastric ulcer.

Selected Thiadiazine-Thione Derivatives Attenuate Neuroinflammation in Chronic Constriction Injury Induced Neuropathy

Neuropathic pain refers to a lesion or disease of peripheral and/or central somatosensory neurons and is an important body response to actual or potential nerve damage. We investigated the therapeutic potential of two thiadiazine-thione [TDT] derivatives, 2-(5-propyl-6-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT1] and 2-(5-propyl-2-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT2] against CCI (chronic constriction injury)-induced neuroinflammation and neuropathic pain. Mice were used for assessment of acute toxicity of TDT derivatives and no major toxic/bizarre responses were observed. Anti-inflammatory activity was assessed using the carrageenan test, and both TDT1 and TDT2 significantly reduced carrageenan-induced inflammation. We also used rats for the induction of CCI and performed allodynia and hyperalgesia-related behavioral tests followed by biochemical and morphological analysis using RT-qPCR, immunoblotting, immunohistochemistry and immunofluorescence. Our findings revealed that CCI induced clear-cut allodynia and hyperalgesia which was reversed by TDT1 and TDT2. To determine the function of TDT1 and TDT2 in glia-mediated neuroinflammation, Iba1 mRNA and protein levels were measured in spinal cord tissue sections from various experimental groups. Interestingly, TDT1 and TDT2 substantially reduced the mRNA expression and protein level of Iba1, implying that TDT1 and TDT2 may mitigate CCI-induced astrogliosis. In silico molecular docking studies predicted that both compounds had an effective binding affinity for TNF-α and COX-2. The compounds interactions with the proteins were dominated by both hydrogen bonding and van der Waals interactions. Overall, these results suggest that TDT1 and TDT2 exert their neuroprotective and analgesic potentials by ameliorating CCI-induced allodynia, hyperalgesia, neuroinflammation and neuronal degeneration in a dose-dependent manner.