Abstract
Three new functionalized 4-aminopyrazole derivatives were synthesized and cyclized with phenyl isothiocyanate to yield the corresponding three pyrazolo[4,3-d]pyrimidine analogues. The DFT quantum chemical calculations were utilized in the determination of the frontier molecular orbital energies and Fukui’s indices. The data showed that they have a low HOMO-LUMO energy gap, ranging from 1.16 to 2.35 eV for 5 and 6, respectively. The newly created analogues' cytotoxic qualities were evaluated in comparison to the reference 5-florouracil (5-Fu) using an in vitro MTT cytotoxicity screening investigation toward four different cell lines, including HCT-116, HepG2, MCF-7, and WI38. The results showed variable potency against human cell lines, with MCF-7 and HepG-2 showing cytotoxic selectivity. The most potent agent against MCF-7 and HCT-116 human cancer cells were found to be aminopyrazole and pyrazolopyrimidine derivatives 4–9. The structure–activity relationships (SAR) for the synthesized compounds were discussed. The examined compounds had superior cytotoxic properties; the most potent derivative 7, had an IC50 ranged from 11.51 ± 0.35 to 21.25 ± 0.37 µM. Meanwhile, quantum chemical computation used independent variables EH, EL, ΔEH-L, χ and η were applied to determine the best way to describe activity. As a result, an increase in the HOMO-LUMO gap and hardness will result in an increase in the anticancer activity. While the EH, EL, and showed negative coefficients, increasing them will decrease the anticancer activity. Furthermore, 5IVE protein's crystal structure for KDM5A was docked with the newly created aminopyrazole and pyrazolopyrimidine derivatives to afford the theoretical prediction on the KDM5A enzyme.