Indomethacin based new triazolothiadiazine derivatives: Synthesis, evaluation of their anticancer effects on T98 human glioma cell line related to COX-2 inhibition and docking studies.

In the current work, new 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine derivatives (1-8) were synthesized via the ring closure reaction of 2-bromoacetophenone derivatives with 4-amino-5-[(5-methoxy-2-methyl-1-(4-chlorobenzoyl)-1H-indol-3-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-thione, which was obtained via the solvent-free reaction of indomethacin with thiocarbohydrazide. MTT assay was carried out to determine the cytotoxic effects of the compounds on T98 human glioma cell line. Among these compounds, 3-[5-methoxy-2-methyl-1-(4-chlorobenzoyl)-1H-indole-3-yl)methyl]-6-(4-methylphenyl)-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine (8) was found to be the most effective compound and therefore flow cytometric method was performed to investigate the apoptotic effect of compound 8. The apoptosis stimulating percentages of compound 8 in comparison with the control group at 50 and 100 μM doses were calculated as 11% and 12%, respectively. Besides, real-time PCR assay was carried out to determine the effects of compound 8 on COX-2, caspase 3, 8 and 9, cytochrome c mRNA levels. According to the real-time PCR analysis, compound 8 reduced COX-2 mRNA levels significantly when compared with the control group, whereas the compound did not cause any significant change in other parameters (Caspase 3, 8, 9, cytochrome c). The docking study suggested that the COX-2 inhibitory effects of compound 8 and indomethacin were similar in the catalytic active site of COX-2. These results indicated that compound 8 showed dose-dependent anticancer activity via the inhibition of COX-2 pathway.