In Vitro Study of Carbonyl Thiourea Derivatives’ Cytotoxicity on Human Corneal Epithelial Cells
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Abstract
Introduction: The global rise of Acanthamoeba keratitis infections has highlighted the shortcomings in the current treatments and prevention approaches for the disease. Therefore, this study is a continuation of our prior work and is intended to investigate the possible adverse effects of using carbonyl thiourea derivatives as alternative ocular drugs for amoebic keratitis on non-targeted human corneal epithelial cells (HCEC) in vitro. Methods: The efficacy and safety profiles of two carbonyl thiourea derivatives, 2-(3-benzoylthioureido)-3-mercaptopropanoic acid (M1) and 2-(3-benzoylthioureido-4-(methylthio)butanoic acid (M2), were tested on HCEC lines using the cytotoxicity assay and microscopic analysis. Results and Discussion: The carbonyl thiourea compounds were found to be non-toxic on HCEC with IC50 of 37.73 µg.mL-1 and 30.68 µg.mL-1 on M1 and M2, respectively. These compounds have selectivity indices (SI) of 14.74 (M1) and 11.38 (M2), indicating moderate selectivity for the targeted Acanthamoeba cells. HCEC-treated cells continued to proliferate in a time-dependent manner without significantly altering the cell population by retaining 90% viability. However, the microscopic examination revealed that HCECs were poorly differentiated and disintegrated, with irregular forms after the compound treatment, as opposed to their original hexagonal morphology of the healthy viable cells. The AO/PI staining indicated that the thiourea compounds impaired HCEC membrane integrity. Conclusions: This study's findings are critical in providing relevant information on carbonyl thiourea compounds if they were to be proposed as anti-amoebic agents in treating or preventing Acanthamoeba keratitis infection.
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References
Abbasi, A., Pakravan, N., & Hassan, Z. M. (2021). Hyaluronic acid optimises therapeutic effects of hydrogen peroxide-induced oxidative stress on breast cancer. Journal of cellular physiology, 236(2), 1494–1514. https://doi.org/10.1002/jcp.29957
Alkharashi, M., Lindsley, K., Law, H. A., & Sikder, S. (2015). Medical interventions for Acanthamoeba keratitis. The Cochrane Database of Systematic Reviews, (2). https://doi.org/10.1002/14651858.CD010792.pub2
Alsam, S., Jeong, S. R., Dudley, R., & Khan, N. A. (2008). Role of human tear fluid in Acanthamoeba interactions with the human corneal epithelial cells. International journal of medical microbiology, 298(3-4), 329–336. https://doi.org/10.1016/j.ijmm.2007.05.010
Anwar, A., Yi, Y. P., Fatima, I., Khan, K. M., Siddiqui, R., Khan, N. A., & Anwar, A. (2020). Antiamoebic activity of synthetic tetrazoles against Acanthamoeba castellanii belonging to T4 genotype and effects of conjugation with silver nanoparticles. Parasitology research, 119(6), 1943–1954. https://doi.org/10.1007/s00436-020-06694-4
Cavet, M. E., Harrington, K. L., VanDerMeid, K. R., Ward, K. W., & Zhang, J. Z. (2012). In vitro biocompatibility assessment of multipurpose contact lens solutions: effects on human corneal epithelial viability and barrier function. Contact lens & anterior eye: the journal of the British Contact Lens Association, 35(4), 163–170. https://doi.org/10.1016/j.clae.2012.02.003
Chen, A.H., Mohd, S.H., Wan Omar, W.E., Kamarulzaman, N., Kasim, M.F., Jackson, A.J. (2021). Characterisation of Metallic Chemical Elements Used as Colour Additives in Cosmetic Colour Contact Lenses and Effects on Human Corneal Epithelial Cell Viability in Vitro. Malaysian Journal of Medicine and Health Science, 17(3), 236-244.
Crowley, L. C., Scott, A. P., Marfell, B. J., Boughaba, J. A., Chojnowski, G., & Waterhouse, N. J. (2016). Measuring Cell Death by Propidium Iodide Uptake and Flow Cytometry. Cold Spring Harbor protocols, (7), 10.1101/pdb.prot087163. https://doi.org/10.1101/pdb.prot087163
de Lacerda, A. G., & Lira, M. (2021). Acanthamoeba keratitis: a review of biology, pathophysiology and epidemiology. Ophthalmic & physiological optics: The Journal of the British College of Ophthalmic Opticians (Optometrists), 41(1), 116–135. https://doi.org/10.1111/opo.12752
de Souza, G. E., Bueno, R. V., de Souza, J. O., Zanini, C. L., Cruz, F. C., Oliva, G., Guido, R. V. C., & Aguiar, A. C. C. (2019). Antiplasmodial profile of selected compounds from Malaria Box: in vitro evaluation, speed of action and drug combination studies. Malaria journal, 18(1), 447. https://doi.org/10.1186/s12936-019-3069-3
Fanselow, N., Sirajuddin, N., Yin, T., W. Huang, A. J., & Stuart, P. M. (2021). Acanthamoeba Keratitis, Pathology, Diagnosis and Treatment. Pathogens, 10(3). https://doi.org/10.3390/pathogens10030323
Fleiszig, S. M. J., Kroken, A. R., Nieto, V., Grosser, M. R., Wan, S. J., Metruccio, M. M. E., & Evans, D. J. (2020). Contact lens-related corneal infection: Intrinsic resistance and its compromise. Progress in retinal and eye research, 76, 100804. https://doi.org/10.1016/j.preteyeres.2019.100804
Gabriel, M. M., McAnally, C., Chen, H., Srinivasan, S., Manoj, V., & Garofalo, R. (2021). Hydrogen Peroxide Disinfecting Solution for Gas Permeable Contact Lenses: A Review of the Antimicrobial Efficacy, Compatibility, and Safety Performance of a One-Step Lens Care System. Clinical Optometry, 13, 7-14. https://doi.org/10.2147/OPTO.S280046
Galluzzi, L., Vitale, I., Aaronson, S. et al. (2018). Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2. Cell death and differentiation, 25(3), 486–541. https://doi.org/10.1038/s41418-017-0012-4
Ghasemi, M., Turnbull, T., Sebastian, S., & Kempson, I. (2021). The MTT Assay: Utility, Limitations, Pitfalls, and Interpretation in Bulk and Single-Cell Analysis. International Journal of Molecular Sciences, 22(23). https://doi.org/10.3390/ijms222312827
Hu, X. M., Li, Z. X., Lin, R. H., Shan, J. Q., Yu, Q. W., Wang, R. X., Liao, L. S., Yan, W. T., Wang, Z., Shang, L., Huang, Y., Zhang, Q., & Xiong, K. (2021). Guidelines for Regulated Cell Death Assays: A Systematic Summary, A Categorical Comparison, A Prospective. Frontiers in cell and developmental biology, 9, 634690. https://doi.org/10.3389/fcell.2021.634690
Hussain, H., Raj, S.L., Ahmad, S., Abd Razak, M.F., Mohamud, W.N.W., Bakar, J., Ghazali, H.M. (2019). Determination of cell viability using acridine orange/propidium iodide dual-spectrofluorometry assay. Cogent Food & Agriculture, 5, 1932.
Ibrahim, M. A., Yusof, M. S., & Amin, N. M. (2014). Anti-amoebic properties of carbonyl thiourea derivatives. Molecules, 19(4), 5191–5204. https://doi.org/10.3390/molecules19045191
Ibrahim, M.A., Zakaria, N.H., & Mohd Yusof, M.S. (2022). Quantitative structure-activity relationship (QSAR) study of newly synthesized carbonyl thiourea derivatives on Acanthamoeba sp. Malaysian Journal of Analytical Science, 26(3), 457 – 477.
Kamiloglu, S., Sari, G., Ozda, I.T., & Capanoglu, E. (2020). Guidelines for cell viability assays. Food Frontiers, 1, 332–349. https://doi.org/10.1002/fft2.44
Konno, T., Melo, E. P., Chambers, J. E., & Avezov, E. (2021). Intracellular Sources of ROS/H2O2 in Health and Neurodegeneration: Spotlight on Endoplasmic Reticulum. Cells, 10(2), 233. https://doi.org/10.3390/cells10020233
Lorenzo-Morales, J., Khan, N. A., & Walochnik, J. (2015). An update on Acanthamoeba keratitis: diagnosis, pathogenesis and treatment. Parasite, 22, 10. https://doi.org/10.1051/parasite/2015010
Nguyen, N. T., & Ho-Huynh, D. (2016). Selective cytotoxicity of a Vietnamese traditional formula, Nam Dia long, against MCF-7 cells by synergistic effects. BMC Complementary and Alternative Medicine, 16. https://doi.org/10.1186/s12906-016-1212-z
Radha Abbas Hasoon, M., & Jawad Kadhim, N. (2021). Improvement of the Selectivity Index (SI) and Cytotoxicity Activity of Doxorubicin Drug by Panax ginseng Plant Extract. Archives of Razi Institute, 76(3), 659–666. https://doi.org/10.22092/ari.2021.355413.1681
Rai, Y., Pathak, R., Kumari, N., Sah, D. K., Pandey, S., Kalra, N., Soni, R., Dwarakanath, B. S., & Bhatt, A. N. (2018). Mitochondrial biogenesis and metabolic hyperactivation limits the application of MTT assay in the estimation of radiation induced growth inhibition. Scientific Reports, 8(1), 1-15. https://doi.org/10.1038/s41598-018-19930-w
Rolón, M., Peixoto de Abreu Lima, A., Coronel, C., Vega, M. C., Pandolfi, E., & Rojas de Arias, A. (2019). The efficacy of new 2,5-dihydroxybenzyl derivatives against Trypanosoma cruzi, Leishmania infantum and Leishmania braziliensis. Journal of infection in developing countries, 13(6), 565–576. https://doi.org/10.3855/jidc.10622
Sangkanu, S., Mitsuwan, W., Mahabusarakam, W., Jimoh, T. O., Wilairatana, P., Girol, A. P., Verma, A. K., de Lourdes Pereira, M., Rahmatullah, M., Wiart, C., Siyadatpanah, A., Norouzi, R., Mutombo, P. N., & Nissapatorn, V. (2021). Anti-Acanthamoeba synergistic effect of chlorhexidine and Garcinia mangostana extract or ?-mangostin against Acanthamoeba triangularis trophozoite and cyst forms. Scientific reports, 11(1), 8053. https://doi.org/10.1038/s41598-021-87381-x
Siddiqui, R., Aqeel, Y., & Khan, N. A. (2016). The Development of Drugs against Acanthamoeba Infections. Antimicrobial Agents and Chemotherapy, 60(11), 6441-6450. https://doi.org/10.1128/AAC.00686-16
Sridhar, M.S. (2018). Anatomy of cornea and ocular surface. Indian Journal of Ophthalmology, 66(2), 190-194. https://doi.org/10.4103/ijo.IJO_646_17
Trocmé, S. D., Hallberg, C. K., Gill, K. S., Gleich, G. J., Tyring, S. K., & Brysk, M. M. (1997). Effects of eosinophil granule proteins on human corneal epithelial cell viability and morphology. Investigative ophthalmology & visual science, 38(3), 593–599.
U.S. Food and Drug Administration (2022). Hydrogen Peroxide Solution. Retrieved from https://www.fda.gov/medical-devices/contact-lenses/hydrogen-peroxide-solution
Yoo, J.H. (2018). Review of Disinfection and Sterilization - Back to the Basics. Infection and Chemotherapy, 50(2), 101-109. https://doi.org/10.3947/ic.2018.50.2.101