Investigation of the effects of thiazole compounds on thioredoxin reductase 1 (TrxR1), glutathione S-transferase (GST), and glutathione reductase (GR) targeted human brain glioblastoma cancer (U-87 MG)

Cancer is a fatal disease that kills thousands of people worldwide. Despite the information produced by research on cancer treatment, applications in cancer treatment are limited. Therefore, scientists' efforts to develop more effective treatment approaches continue. In the study, we aimed to determine the anticancer potential of amino thiazole compounds on human glioblastoma (U-87 MG) and human dermal fibroblast (HDFa) cells and their inhibition effects on enzymes that cause multidrug resistance in cancer cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide cell viability test was performed to understand the cytotoxic properties of thiazole derivatives. The cellular death mechanisms behind thiazole application were investigated using flow cytometry analysis. According to cell viability analysis, thiazole derivatives exhibited a greater effect on U-87 MG than the HDFa cell line in terms of cytotoxicity. Flow cytometry showed higher apoptotic cell death in U-87 MG cells than in the HDFa cell line. It can be concluded that thiazole compounds exert anticancer effects on U-87 MG and HDFa as well as show apoptotic properties. Their effects on thioredoxin reductase 1 (TrxR1), glutathione S-transferase (GST), and glutathione reductase (GR) activities, which are important in the development of chemotherapeutic methods, were also examined. From the results obtained, it was determined that the 2-amino-4-(p-tolyl)thiazole (T7) compound significantly suppressed both TrxR1 and GST activities, and the 2-amino-6-methylbenzothiazole (T8) compound significantly suppressed both TrxR1 and GST activities. Compound T7 was determined to be a selective inhibitor for TrxR1 and GST targeting, and compound T8 was determined to be a selective inhibitor for TrxR1 and GR targeting glioblastoma treatment.

Structure-Activity Relationship of Methyl 4-Aminobenzoate Derivatives as Being Drug Candidate Targeting Glutathione Related Enzymes: in Vitro and in Silico Approaches

A thiol compound, glutathione, is essential for healthy cell defence against xenobiotics and oxidative stress. Glutathione reductase (GR) and glutathione S-transferase (GST) are two glutathione-related enzymes that function in the antioxidant and the detoxification systems. In this study, potential inhibitory effects of methyl 4-aminobenzoate derivatives on GR and GST were examined in vitro. GR and GST were isolated from human erythrocytes with 7.63 EU/mg protein and 5.66 EU/mg protein specific activity, respectively. It was found that compound 1 (methyl 4-amino-3-bromo-5-fluorobenzoate with K_i value of 0.325±0.012 μM) and compound 5 (methyl 4-amino-2-nitrobenzoate with K_i value of 92.41±22.26 μM) inhibited GR and GST stronger than other derivatives. Furthermore, a computer-aided method was used to predict the binding affinities of derivatives, ADME characteristics, and toxicities. Derivatives 4 (methyl 4-amino-2-bromobenzoate) and 6 (methyl 4-amino-2-chlorobenzoate) were estimated to have the lowest binding energies into GR and GST receptors, respectively according to results of in silico studies.

The effect of brimonidine and proparacaine on metabolic enzymes: Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase

Oxidative stress is to upregulate the pentose phosphate pathway (PPP). The PPP consists of two functional branches, glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconaste dehydrogenase (6PGD). Glutathione reductase (GR) has a significant role in catalyzing an oxidized glutathione form into a reduced form. The purpose of this study is to investigate the effects of brimonidine and proparacaine on the activity of 6PGD, G6PD, and GR enzymes purified from human erythrocytes. Brimonidine displayed considerable inhibition profile against G6PD with IC₅₀ value and K_I constant of 29.93 ± 3.56 and 48.46 ± 0.66 μM, respectively. On the other hand, proparacaine had no inhibitory effect against G6PD. K_I values were found to be 66.06 ± 0.78 and 811.50 ± 11.13 μM for brimonidine and proparacaine, respectively, for 6PGD. K_I values were found to be 144.10 ± 2.01 and 1,654.00 ± 26.29 μM for brimonidine and proparacaine, respectively, for GR. Herein, also in silico molecular docking studies were performed between drugs and enzymes.