Anticancer Activity and In Silico ADMET Properties of 2,4,5-Trisubstitutedthiazole Derivatives.

BACKGROUND: Recently, a series of 15 compounds with 2,4,5-trisubstitutedthiazole scaffold having 2- amino/amido/ureido functional groups attached with 5-aryl and 4-carboxylic acid/ester groups (1-15) were reported from our research group as novel potential inhibitors of carbonic anhydrase III (CA III) enzyme. Several research studies revealed the potential role of CA inhibitors as anticancer agents, giving us the impetus to further explore these compounds for their potential as anticancer agents. OBJECTIVES: The objective of this study is to investigate the potential of 2,4,5-trisubstitutedthiazole derivatives (1-15) for their possible cytotoxic activity (in vitro), and to calculate (in silico) the absorption, distribution, metabolism, excretion and toxicity (ADMET) properties to evaluate the drug-likeness of these compounds. METHODS: Cytotoxic activity (in vitro) was carried out on two breast cancer cell lines (MCF7 and MDA231), and the lymphoblastoid human erythroleukemia cell line (K562) using 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay. Doxorubicin was used as a positive control. ADMET properties were calculated (in silico) using the QikProp module of Schrodinger. RESULTS: Compounds 6 and 9 with a phenylureido group at 2-position, and a methyl-carboxylate moiety at 4-position having para-tolyl and benzyl moiety, respectively at the 5-position of the thiazole ring showed significant cytotoxicity against all the three cell lines. In particular, compound 6 with para-tolyl group at 5-position exhibited the most potent inhibitory effect on the viability of MCF7, MDA231 and K562 cells, with IC50 values of 22, 26 and 11 µM, respectively. Notably, all the highly active compounds possess a phenyluriedo group at 2-- position with a methyl ester group at 4-position, indicating the probable role of these substituents in the target interaction and inducing cytotoxicity. Interestingly, compounds 1-4 and 10-13 with a free amino group at 2-position did not show any cytotoxic effect on the K562 cell line, while exhibiting mild to moderate cytotoxicity against the MCF7 and MDA231 cell lines. However, none of the tested compounds showed any activity against normal human dermal fibroblast cells indicating the safety/tolerability of the examined concentrations. Furthermore, these compounds also exhibited satisfactory ADMET properties (in silico), without violating Lipinski's rule of five. CONCLUSION: The most active compounds 6 and 9 predicted to have good oral absorption and low human serum protein binding, exhibiting no reactive functional group and probable CNS activity compared with 95% of the known oral drugs as predicted (in silico) by QikProp. Thus, compounds 6 and 9 can be considered as lead molecules for further modification and discovery of novel anticancer agents with nanomolar potency.

Synthesis and evaluation of 2,4,5-trisubstitutedthiazoles as carbonic anhydrase-III inhibitors.

A series of 17 compounds (12-16 b) with 2,4,5-trisubstitutedthiazole scaffold having 5-aryl group, 4-carboxylic acid/ester moiety, and 2-amino/amido/ureido functional groups were synthesised, characterised, and evaluated for their carbonic anhydrase (CA)-III inhibitory activities using the size exclusion Hummel-Dreyer method (HDM) of chromatography. Compound 12a with a free amino group at the 2-position, carboxylic acid moiety at the 4-position, and a phenyl ring at the 5-position of the scaffold was found to be the most potent CA-III inhibitor (Ki = 0.5 µM). The presence of a carboxylic acid group at the 4-position of the scaffold was found to be crucial for the CA-III inhibitory activity. Furthermore, replacement of the free amino group with an amide and urea group resulted in a significant reduction of activity (compounds 13c and 14c, Ki = 174.1 and 186.2 µM, respectively). Thus, compound 12a (2-amino-5-phenylthiazole-4-carboxylic acid) can be considered as the lead molecule for further modification and development of more potent CA-III inhibitors.

Cytotoxicity and Antimycobacterial Properties of Pyrrolo[1,2-a]quinoline Derivatives: Molecular Target Identification and Molecular Docking Studies.

A series of ethyl 1-(substituted benzoyl)-5-methylpyrrolo[1,2-a]quinoline-3-carboxylates 4a-f and dimethyl 1-(substituted benzoyl)-5-methylpyrrolo[1,2-a]quinoline-2,3-dicarboxylates 4g-k have been synthesized and evaluated for their anti-tubercular (TB) activities against H37Rv (American Type Culture Collection (ATCC) strain 25177) and multidrug-resistant (MDR) strains of Mycobacterium tuberculosis by resazurin microplate assay (REMA). Molecular target identification for these compounds was also carried out by a computational approach. All test compounds exhibited anti-tuberculosis (TB) activity in the range of 8-128 µg/mL against H37Rv. The test compound dimethyl-1-(4-fluorobenzoyl)-5-methylpyrrolo[1,2-a]quinoline-2,3-dicarboxylate 4j emerged as the most promising anti-TB agent against H37Rv and multidrug-resistant strains of Mycobacterium tuberculosis at 8 and 16 µg/mL, respectively. In silico evaluation of pharmacokinetic properties indicated overall drug-likeness for most of the compounds. Docking studies were also carried out to investigate the binding affinities as well as interactions of these compounds with the target proteins.