Recent Advances in the Development of Pyrazole Derivatives as Anticancer Agents

Pyrazole derivatives, as a class of heterocyclic compounds, possess unique chemical structures that confer them with a broad spectrum of pharmacological activities. They have been extensively explored for designing potent and selective anticancer agents. In recent years, numerous pyrazole derivatives have been synthesized and evaluated for their anticancer potential against various cancer cell lines. Structure-activity relationship studies have shown that appropriate substitution on different positions of the pyrazole ring can significantly enhance anticancer efficacy and tumor selectivity. It is noteworthy that many pyrazole derivatives have demonstrated multiple mechanisms of anticancer action by interacting with various targets including tubulin, EGFR, CDK, BTK, and DNA. Therefore, this review summarizes the current understanding on the structural features of pyrazole derivatives and their structure-activity relationships with different targets, aiming to facilitate the development of potential pyrazole-based anticancer drugs. We focus on the latest research advances in anticancer activities of pyrazole compounds reported from 2018 to present.

Anticancer evaluation and molecular docking of new pyridopyrazolo-triazine and pyridopyrazolo-triazole derivatives

3-Amino-4,6-dimethylpyrazolopyridine was applied as a precursor for the synthesis of some new pyridopyrazolo-triazine and pyridopyrazolo-triazole derivatives through diazotization, followed by coupling with many 2-cyanoacetamide compounds, ethyl 3-(phenylamino)-3-thioxopropanoate, 3-oxo-N-phenylbutanethioamide, and α-bromo-ketone reagents [namely; 2-bromo-1-(4-fluorophenyl)ethan-1-one, 5-bromo-2-(bromoacetyl)thiophene, 3-(2-bromoacetyl)-2H-chromen-2-one and/or 3-chloroacetylacetone]. The prepared compounds were identified by spectroscopic analyses as IR, ¹H NMR, and mass data. The anticancer activity of these pyrazolopyridine analogues was investigated in colon, hepatocellular, breast, and cervix carcinoma cell lines. The pyridopyrazolo-triazine compound 5a substituted with a carboxylate group gave a distinguished value of IC₅₀ = 3.89 µM against the MCF-7 cell line compared to doxorubicin as a reference drug. Also, the pyridopyrazolo-triazine compound 6a substituted with the carbothioamide function gave good activity toward HCT-116 and MCF-7 cell lines with IC₅₀ values of 12.58 and 11.71 µM, respectively. The discovered pyrazolopyridine derivatives were studied theoretically by molecular docking, and this study exhibited suitable binding between the active sides of pyrazolopyridine ligands and proteins (PDB ID: 5IVE). The pyridopyrazolo-triazine compound 6a showed the highest free binding energy (- 7.8182 kcal/mol) when docked inside the active site of selected proteins.

Crystal structure analysis of ethyl 3-(4-chloro-phen-yl)-1,6-dimethyl-4-methyl-sulfanyl-1H-pyrazolo[3,4-b]pyridine-5-carboxyl-ate

In the title compound, C18H18ClN3O2S, the dihedral angle between the fused pyrazole and pyridine rings is 3.81 (9)°. The benzene ring forms dihedral angles of 35.08 (10) and 36.26 (9)° with the pyrazole and pyridine rings, respectively. In the crystal, weak C-H⋯O hydrogen bonds connect mol-ecules along [100].