Skip to main content
Article
Licensed
Unlicensed Requires Authentication

Identification of bis-thiazole linked oxazine Schiff bases: synthesis, in-vitro biological evaluation and computational insights toward potent urease and thymidine phosphorylase inhibitors

  • ORCID logo EMAIL logo , , , , , , , , and
Published/Copyright: January 20, 2026
Pure and Applied Chemistry
From the journal Pure and Applied Chemistry

Abstract

Recent advances in molecular therapeutics underscore the central role of dysregulated endogenous enzymes in the onset and progression of non-infectious diseases. Urease and thymidine phosphorylase are two clinically relevant enzymes implicated in microbial virulence, inflammation, and cancer biology, yet potent dual modulators remain limited. Here, we report the design and synthesis of a novel library of bis-thiazole linked oxazine Schiff base hybrids (1–10) as candidate dual-enzyme inhibitors. Structural elucidation using FT-IR, 1HNMR, 13C NMR spectroscopy, and HRMS confirmed the structural integrity of the synthesized scaffolds. Biological evaluation revealed potent inhibitory activity across the series, with compounds 1, 2, 5 and 8 demonstrating superior efficacy compared with the standard inhibitors thiourea and 7-deazaxanthine. Notably, compound-1 acted as the most effective dual inhibitor, achieving IC50 values of 4.30 ± 0.73 µM (thymidine phosphorylase) and 3.90 ± 0.84 µM (urease). Molecular docking analyses further identify stable binding conformations and extensive interaction networks within the catalytic sites of both targets, providing a structural rationale for the observed potencies. These findings position the bis-thiazole linked oxazine Schiff base scaffold as a compelling chemotype for next-generation enzyme-directed therapeutics. The strong inhibitory profiles and well-defined molecular interactions provide a clear rationale for further structure-guided optimization. Together, these results lay the groundwork for advancing this scaffold toward translational development.

Keywords: Bis-thiazole; human thymidine phosphorylase; molecular docking; oxazine; SAR; Schiff base
Corresponding authors: Yousaf Khan, Department of Chemistry, COMSATS University Islamabad, 45550, Islamabad, Pakistan, e-mail: ; and Rubina Adnan, Department of Computer Science, COMSATS University Islamabad, 45550, Islamabad, Pakistan, e-mail:

  1. Research ethics: Not applicable.

  2. Informed consent: Not applicable.

  3. Author contributions: Y. Khan; Project Supervisor, Methodology, data curation, Conceptualization, Experimental, MU. Naeem; Visualization, Conceptualization, original draft Write-up, SF. Naqvi; Experimental, formal analysis, investigation, validation, S.Aslam; Formal Analysis, Biological activity, R. Adnan; Software, analyze data, formal analysis, M. Naseem- Formal analysis, Review, S.B. Fatima- Investigation, Azmatullah-project administration, supervision, Enzyme inhibition; U. Gulshan: Formal Analysis, Writing-Original Draft S. Aminullah; writing-review and editing.

  4. Use of Large Language Models, AI and Machine Learning Tools: Not applicable.

  5. Conflict of interest: The authors declare no competing interests.

  6. Research funding: Not applicable.

  7. Data availability: All data obtained or analyzed during this study are included in this article.

References

1. Ojha, A.; Bandyopadhyay, T. K.; Das, D. A Comprehensive Review on Microbial Urease: Features and Industrial Applications. Crit. Rev. Biotechnol. 2025, 1–24; https://doi.org/10.1080/07388551.2025.2529589.Search in Google Scholar PubMed

2. Mazzei, L.; Musiani, F.; Ciurli, S. The Structure-Based Reaction Mechanism of Urease, A Nickel Dependent Enzyme: Tale of a Long Debate. JBIC, J. Biol. Inorg. Chem. 2020, 25 (6), 829–845; https://doi.org/10.1007/s00775-020-01808-w.Search in Google Scholar PubMed PubMed Central

3. Yang, W.; Peng, Z.; Wang, G. An Overview: Metal-Based Inhibitors of Urease. J. Enzyme Inhib. Med. Chem. 2023, 38 (1), 361–375; https://doi.org/10.1080/14756366.2022.2150182.Search in Google Scholar PubMed PubMed Central

4. Almarmouri, C.; El-Gamal, M. I.; Haider, M.; Hamad, M.; Qumar, S.; Sebastian, M.; Ghemrawi, R.; Muhammad, J. S.; Burucoa, C.; Khoder, G. Anti-Urease Therapy: A Targeted Approach to Mitigating Antibiotic Resistance in Helicobacter pylori While Preserving the Gut Microflora. Gut Pathog. 2025, 17 (1), 37; https://doi.org/10.1186/s13099-025-00708-1.Search in Google Scholar PubMed PubMed Central

5. Sugano, K.; Suzuki, C.; Ota, M.; Iwakiri, R. Gastric Cancer Risk After Helicobacter pylori Eradication in Gastritis and Peptic Ulcer: A Retrospective Cohort Study in Japan. BMC Gastroenterol. 2025, 25 (1), 1–11; https://doi.org/10.1186/s12876-025-04034-3.Search in Google Scholar PubMed PubMed Central

6. Kunkalienkar, S.; Gandhi, N. S.; Gupta, A.; Saha, M.; Pai, A.; Shetty, S.; Gupta, A.; Dhas, N.; Hariharapura, R. C.; Nandakumar, K.; Narasimhaswamy, N.; Moorkoth, S. Targeting Urease: A Promising Adjuvant Strategy for Effective Helicobacter pylori Eradication. ACS Omega 2025, 10 (27), 28643–28669; https://doi.org/10.1021/acsomega.5c02725.Search in Google Scholar PubMed PubMed Central

7. Arshad, S.; Maalik, A.; Rehman, W.; Khan, Y.; Alanazi, M. M.; Sarfraz, H.; Rasheed, L. Facile Indazole-endowed Thiadiazole Hybrid Derivatives as Antibacterial, Anti-diabetic and Thymidine Phosphorylase Inhibitors: An Insight to Experimental, in-vitro Biological Potential and Computational Approaches. Saudi Pharm. J. 2025, 33 (4), 20; https://doi.org/10.1007/s44446-025-00003-9.Search in Google Scholar PubMed PubMed Central

8. Karatkevich, D.; Losmanova, T.; Zens, P.; Deng, H.; Dubey, C.; Zhang, T.; Casty, C.; Gao, Y.; Neppl, C.; Berezowska, S.; Wang, W.; Peng, R. W.; Schmid, R. A.; Dorn, P.; Marti, T. M. Chemotherapy Increases CDA Expression and Sensitizes Malignant Pleural Mesothelioma Cells to Capecitabine Treatment. Sci. Rep. 2024, 14 (1), 18206; https://doi.org/10.1038/s41598-024-69347-x.Search in Google Scholar PubMed PubMed Central

9. Khan, Y.; Hussain, R.; Maqsood, S.; Naeem, M. U.; Araújo da Costa, R.; Sattar, A.; Binsaleh, A. Y.; Alkhatib, S. N.; Al-Hoshani, N.; Al-Joufi, F. A.; ul Haq, T.; Khan, A. A. Design, Synthesis and Computational Approaches of Highly Potent Thiazole-Based Isoxazole Targeting Thymidine Phosphorylase and Urease Inhibitors. J. Comput. Biophys. Chem. 2025, 1–15; https://doi.org/10.1142/s2737416526500067.Search in Google Scholar

10. Rauf, A.; Khan, M.; Rashid, U.; Saeed, A.; Shah, Z. A.; Ahmad, Z.; Alamri, A. S.; Alsanie, W. F.; Khan, I.; Hussain, H.; Alhomrani, M.; Iriti, M. Thymidine Phosphorylase Inhibitory Potential and Molecular Docking Studies of Secondary Metabolites Isolated from Fernandoa adenophylla (Wall. ex G. Don) Steenis. Chem. Biodiversity 2025, e202500449; https://doi.org/10.1002/cbdv.202500449.Search in Google Scholar PubMed PubMed Central

11. Abdel‐Megid, M.; Ali, T. E.; Salem, M. E.; Abouelenein, M. G.; Nassar, I. F.; Zaki, M. E. Ring‐Chain Tautomerism (Part II): Synthetic Applications of Biologically Active Five‐Membered Heterocycles with Two Heteroatoms. J. Heterocycl. Chem. 2025, 1–10; https://doi.org/10.1002/jhet.70075.Search in Google Scholar

12. Assress, H. A.; Selvarajan, R.; Nyoni, H.; Mamba, B. B.; Msagati, T. A. Antifungal Azoles and Azole Resistance in the Environment: Current Status and Future Perspectives–A Review. Rev. Environ. Sci. Biotechnol. 2021, 20 (4), 1011–1041; https://doi.org/10.1007/s11157-021-09594-w.Search in Google Scholar

13. Sanguinetti, M.; Posteraro, B.; Lass‐Flörl, C. Antifungal Drug Resistance Among Candida Species: Mechanisms and Clinical Impact. Mycoses 2015, 58, 2–13; https://doi.org/10.1111/myc.12330.Search in Google Scholar PubMed

14. Arshad, M. F.; Alam, A.; Alshammari, A. A.; Alhazza, M. B.; Alzimam, I. M.; Alam, M. A.; Mustafa, G.; Ansari, M. S.; Alotaibi, A. M.; Alotaibi, A. A.; Kumar, S.; Asdaq, S. M. B.; Imran, M.; Deb, P. K.; Venugopala, K. N.; Jomah, S. Thiazole: a Versatile Standalone Moiety Contributing to the Development of Various Drugs and Biologically Active Agents. Molecules 2022, 27 (13), 3994; https://doi.org/10.3390/molecules27133994.Search in Google Scholar PubMed PubMed Central

15. Guan, Q.; Xing, S.; Wang, L.; Zhu, J.; Guo, C.; Xu, C.; Zhao, Q.; Wu, Y.; Chen, Y.; Sun, H. Triazoles in Medicinal Chemistry: Physicochemical Properties, Bioisosterism, and Application. J. Med. Chem. 2024, 67 (10), 7788–7824; https://doi.org/10.1021/acs.jmedchem.4c00652.Search in Google Scholar PubMed

16. Fathy, U. Thiazole Derivatives: Prospectives and Biological Applications. J. Sulfur Chem. 2024, 45 (5), 786–828; https://doi.org/10.1080/17415993.2024.2338270.Search in Google Scholar

17. Dondoni, A.; Marra, A. Thiazole-Mediated Synthetic Methodology. Chem. Rev. 2004, 104 (5), 2557–2600; https://doi.org/10.1021/cr020079l.Search in Google Scholar PubMed

18. Gupta, N.; Saini, V.; Basavarajaiah, S. M.; Dar, M. O.; Das, R.; Dahiya, R. S. 1, 3‐Oxazine as a Promising Scaffold for the Development of Biologically Active Lead Molecules. ChemistrySelect 2023, 8 (39), e202301456; https://doi.org/10.1002/slct.202301456.Search in Google Scholar

19. Lathwal, A.; Mathew, B. P.; Nath, M. Syntheses, Biological and Material Significance of Dihydro [1, 3] Oxazine Derivatives: An Overview. Curr. Org. Chem. 2021, 25 (1), 133–174; https://doi.org/10.2174/1385272824999201008154659.Search in Google Scholar

20. Zhang, W.; Yang, J.; Tang, X.; Zhang, J.; Gan, X. Novel N-Phenyltriazinone Derivatives Containing Oxazine/Oxime Fragments as Promising Protoporphyrinogen IX Oxidase Inhibitors. J. Agric. Food Chem. 2025, 72 (24), 14857–14866; https://doi.org/10.1021/acs.jafc.5c00979.Search in Google Scholar PubMed

21. Martinez, V.; Henary, M. Nile Red and Nile Blue: Applications and Syntheses of Structural Analogues. Chem. Eur J. 2016, 22 (39), 13764–13782; https://doi.org/10.1002/chem.201601570.Search in Google Scholar PubMed

22. Zinad, D. S.; Mahal, A.; Mohapatra, R. K.; Sarangi, A. K.; Pratama, M. R. F. Medicinal Chemistry of Oxazines as Promising Agents in Drug Discovery. Chem. Biol. Drug Des.2020, 95 (1), 16–47; https://doi.org/10.1111/cbdd.13633.Search in Google Scholar PubMed

23. Sadhu, C.; Mitra, A. K. Synthetic, Biological and Optoelectronic Properties of Phenoxazine and its Derivatives: A State of the Art Review. Mol. Diversity 2024, 28 (2), 965–1007; https://doi.org/10.1007/s11030-023-10619-5.Search in Google Scholar PubMed PubMed Central

24. Pola, S. Significance of Thiazole-based Heterocycles for Bioactive Systems. In Scope of Selective Heterocycles from Organic and Pharmaceutical Perspective; IntechOpen: Rijeka, Croatia, Vol. 1, 2016; pp 13–62.10.5772/62077Search in Google Scholar

25. Akhdhar, A. A Novel, Simple, and Reliable Spectrophotometric Determination of Total Hexavalent Chromium by Complexation with a New Reagent of Thiazole Linked to 2H‐Chromen‐2‐One. Int. J. Anal. Chem. 2023, 2023 (1), 2042221; https://doi.org/10.1155/2023/2042221.Search in Google Scholar PubMed PubMed Central

26. Rahim, F.; Javed, M. T.; Ullah, H.; Wadood, A.; Taha, M.; Ashraf, M.; Khan, M. A.; Khan, M. A.; Khan, F.; Mirza, S.; Khan, K. M. Synthesis, Molecular Docking, Acetylcholinesterase and Butyrylcholinesterase Inhibitory Potential of Thiazole Analogs as New Inhibitors for Alzheimer Disease. Bioorg. Chem. 2015, 62, 106–116; https://doi.org/10.1016/j.bioorg.2015.08.002.Search in Google Scholar PubMed

27. Hussain, R.; Rehman, W.; Rahim, F.; Mahmoud, A. M.; Alanazi, M. M.; Khan, S.; Rasheed, L.; Khan, I.; Khan, I. Synthetic Transformation of 6-Fluoroimidazo [1, 2-a] Pyridine-3-carbaldehyde into 6-Fluoroimidazo [1, 2-a] Pyridine-Oxazole Derivatives: in Vitro Urease Inhibition and in Silico Study. Saudi Pharm. J. 2023, 31 (8), 101667; https://doi.org/10.1016/j.jsps.2023.05.026.Search in Google Scholar PubMed PubMed Central

28. Kalantarian, S. J.; Kefayati, H.; Montazeri, N. Synthesis and Antimicrobial Evaluation of Novel Tris‐Thiadiazole Derivatives. J. Heterocycl. Chem. 2022, 59, 1253–1259; https://doi.org/10.1002/jhet.4466.Search in Google Scholar

29. Tahira, S.; Younas, F.; Saeed, A.; Afzal, D. e. S.; Shafiq, Z.; Althobaiti, S. A.; El-Bahy, S. M.; Hökelek, T. Synthesis, Crystal Structure, DFT, Hirshfeld Surface Analysis, Multitarget Enzyme Inhibition Studies, Anticancer, Annexin V-FITC Apoptosis Assay and Computational Studies of New ketoprofen-thiourea Conjugate. J. Mol. Struct. 2025, 1333, 141567; https://doi.org/10.1016/j.molstruc.2025.141567.Search in Google Scholar

30. Khan, Y.; Hussain, R.; Rehman, W.; Khan, S.; Maalik, A.; Iqbal, T.; Aziz, T.; Afridi, M. I.; Alharbi, M.; Alasmari, A. F. In-vitro and in-silico Assessment of thiazole-thiazolidinone Derivatives as Selective Inhibitors of Urease and α-glucosidase. Future Med. Chem. 2024, 16 (24), 2627–2636; https://doi.org/10.1080/17568919.2024.2432303.Search in Google Scholar PubMed PubMed Central

31. Taha, M.; Rahim, F.; Khan, A. A.; Anouar, E. H.; Ahmed, N.; Shah, S. A. A.; Ibrahim, M.; Zakari, Z. A. Synthesis of Diindolylmethane (DIM) Bearing Thiadiazole Derivatives as a Potent Urease Inhibitor. Sci. Rep. 2020, 10, 7969; https://doi.org/10.1038/s41598-020-64729-3.Search in Google Scholar PubMed PubMed Central

32. Taha, M.; Ismail, N. H.; Imran, S.; Wadood, A.; Rahim, F.; Khan, K. M.; Riaz, M. Synthesis and Molecular Docking Study of Piperazine Derivatives as Potent Urease Inhibitors. Bioorg. Chem. 2016, 66, 80–87; https://doi.org/10.1016/j.bioorg.2016.03.010.Search in Google Scholar PubMed

33. Ullah, H.; Liaqat, A.; Khan, Q. U.; Taha, M.; Khan, F.; Rahim, F.; Uddin, I.; Rehman, Z. U. Synthesis, in Vitro Thymidine Phosphorylase Activity and Molecular Docking Study of Thiadiazole Bearing Isatin Analogs. Chem. Pap. 2021, 1–12, https://doi.org/10.1007/s11696-021-01842-1.Search in Google Scholar

34. Khan, S.; Hussain, R.; Khan, Y.; Iqbal, T.; Anwar, S.; Aziz, T.; Alharbi, M. In Vitro Enzymatic, in Silico ADME and Molecular Docking Based Analysis for the Identification of Novel bis-indole Containing triazine–thiazole Hybrids Derivatives as Promising Urease Inhibitors. Z. Naturforsch. C 2024, 79 (7-8), 195–207; https://doi.org/10.1515/znc-2024-0061.Search in Google Scholar PubMed

35. Taha, M.; Ismail, N. H.; Khan, A.; Shah, S. A. A.; Anwar, A.; Halim, S. A.; Fatmi, M. Q.; Imran, S.; Rahim, F.; Khan, K. M.; Khan, K. M. Synthesis of Novel Derivatives of Oxindole, their Urease Inhibition and Molecular Docking Studies. Bioorg. Med. Chem. Lett. 2015, 25 (16), 3285–3289; https://doi.org/10.1016/j.bmcl.2015.05.069.Search in Google Scholar PubMed

36. Farghaly, T. A.; Rehman, W.; Khan, Y.; Sarfraz, H. Synthesis, Biological Screening and Computational Analysis of Thiazole Linked Thiazolidinone Schiff Bases as Anti-alzheimer’s Drug Candidates. Bioorg. Chem. 2025, 108812; https://doi.org/10.1016/j.bioorg.2025.108812.Search in Google Scholar PubMed

37. Hawsawi, M. B.; Khan, S.; Iqbal, T.; Hussain, R.; Khan, Y.; Zahoor, T.; Dera, A. A. Synthesis, Characterization and Molecular Modeling Approach of Hybrid Pyrazole Based Thiazolidinone Derivatives: An Estimation and Inhibition of Diabetes Mellitus. J. Mol. Struct. 2025, 1322, 140407; https://doi.org/10.1016/j.molstruc.2024.140407.Search in Google Scholar

38. Parveen, S.; Khan, S.; Iqbal, T.; Dera, A. A.; Hussain, R.; Khan, Y. Synthesis, Spectroscopy and Biological Investigation via DFT, ADMET and Molecular Docking of Thiadiazole/Oxadiazole Based Bis-Schiff Bases: A Potential Towards Diabetes and Microbes. Results Chem. 2024, 11, 101787; https://doi.org/10.1016/j.rechem.2024.101787.Search in Google Scholar

39. Jamal, U.; Khan, S.; Iqbal, T.; Rahim, F.; Hussain, R.; Khan, Y.; Darwish, H. W. Compara Tive Studies via in Vitro Anti-alzheimer of Thiazolidinone Based Chalcone Derivatives: Insight into the Synthesis, Molecular Docking and ADME Analysis. J. Mol. Struct. 2025, 1331, 141532; https://doi.org/10.1016/j.molstruc.2025.141532.Search in Google Scholar

40. Ain, Q. U.; Hayat, S.; Khan, J.; Ullah, H.; Taha, M.; Khan, U.; Khan, M. U.; Rahim, F.; Nabi, M.; Gurbanova, L. Design, Synthesis, Biological Assessment, and Molecular Docking of Pyrrole-Derived Bis-Schiff Bases as Potential Urease Inhibitors. Chem. Data Collect. 2025, 101193; https://doi.org/10.1016/j.cdc.2025.101193.Search in Google Scholar

41. Khan, Y.; Solangi, M.; Khan, K. M.; Ullah, N.; Iqbal, J.; Hussain, Z.; Khan, I. A.; Salar, U.; Taha, M. Exploration of Thiazine Schiff Bases as Promising Urease Inhibitors: Design, Synthesis, Enzyme Inhibition, Kinetic Analysis, ADME/T Evaluation, and Molecular Docking Studies. Int. J. Biol. Macromol. 2024, 281, 136361; https://doi.org/10.1016/j.ijbiomac.2024.136361.Search in Google Scholar PubMed

42. Hussain, R.; Afridi, M. I.; Khan, S.; Khan, Y.; Iqbal, T.; Rasheed, L.; Islam, M. S.; Dahlous, K. A. Insight from Molecular Modeling and ADMET Analysis: Design, Synthesis and in Vitro Acetylcholinesterase and Butyrylcholinesterase Assessment of Thiazolidinone Containing Benzoxazole Hybrids Derivatives. J. Mol. Struct. 2025, 1322, 140589; https://doi.org/10.1016/j.molstruc.2024.140589.Search in Google Scholar

43. Masood, N.; Hussain, R.; Khan, S.; Rahim, F.; Mumtaz, S.; Taha, M.; Ur Rahman Abid, O.; Iqbal, T.; Adnan Ali Shah, S.; Omar Al Wesabi, E.; Magam, S. M. Synthesis, in Vitro Enzymatic Inhibition, and Molecular Modeling of Novel Piperazine‐Based Bis‐Schiff Base Derivatives as Promising Anti‐Urease Agents. ChemistrySelect 2024, 9 (31), e202401106; https://doi.org/10.1002/slct.202401106.Search in Google Scholar

44. Biswas, S.; Talapatra, S. N. Microbial Volatile Organic Compounds as Indoor Air Pollutants: Prediction of Acute Oral Toxicity, Hepatotoxicity, Immunotoxicity, Genetic Toxicity Endpoints, Nuclear Receptor Signalling and Stress Response Pathways by Using Protox-II Webserver. J. Adv. Sci. Res. 2019, 10 (03 Suppl 1), 186–195.Search in Google Scholar

45. Daina, A.; Michielin, O.; Zoete, V. Swissadme: A Free Web Tool to Evaluate Pharmacokinetics, Drug-Likeness and Medicinal Chemistry Friendliness of Small Molecules. Sci. Rep. 2017, 7 (1), 42717; https://doi.org/10.1038/srep42717.Search in Google Scholar PubMed PubMed Central

46. Arshad, S.; Maalik, A.; Rehman, W.; Khan, Y.; Rasheed, L.; Alanazi, A. S.; Hefnawy, M.; Hussain, A.; Begum, S.; Yar, M.; Ayub, K. Novel Hybrid Indazole-Based 2, 4-Dihydro-3H-1, 2, 4-Triazole-3-Thione Derivatives: Design, Synthesis, Spectroscopic Characterization, SAR, Molecular Docking, Pharmacokinetics and Toxicological Activities. Pure Appl. Chem. 2025, 1–10; https://doi.org/10.1515/pac-2025-0459.Search in Google Scholar

Supplementary Material

This article contains supplementary material (https://doi.org/10.1515/pac-2025-0649).

Received: 2025-10-20
Accepted: 2026-01-05
Published Online: 2026-01-20

© 2026 IUPAC & De Gruyter

https://doi.org/10.1515/pac-2025-0649
Keywords for this article
Bis-thiazole; human thymidine phosphorylase; molecular docking; oxazine; SAR; Schiff base
Downloaded on 25.4.2026 from https://www.degruyterbrill.com/document/doi/10.1515/pac-2025-0649/html?lang=en
Scroll to top button