Synthesis and in vitro investigation of novel cytotoxic pyrimidine and pyrazolopyrimidne derivatives showing apoptotic effect

Abstract

A series of novel derivatives of hydrazinylpyrimidines, pyrazolylpyrimidines and 3-amino[3,4-d]pyrazolopyrimidines have been synthesized and tested for their in vitro cytotoxic activity against 60 tumor cell lines by NCI. The in vitro cytotoxic IC₅₀ values for the most active compounds were determined against the colon-KM12 cell line (5d, 7c and 7d), breast-MCF-7 (6a) and melanoma-MDA-MB-435 (6h) using 5-fluorouracil (5-FU) as a positive control. Derivatives 5d and 7c were found to be the most potent derivatives against KM12 cell line (IC₅₀ = 1.73 and 1.21 µM, respectively) with a high selectivity index (SI) (18.82 and 35.49, respectively) compared to 5-FU (IC₅₀ = 12.26 µM, SI = 1.93). Compounds 5d and 7c were further investigated for their apoptotic behavior in KM12 cell line. The investigations showed the up-regulation of caspase 3/9 and the pro-apoptotic factor Bax. On the other hand, the expression of the anti-apoptotic factor Bcl-2, was down-regulated, as well as its inhibition at a nanomolar concentration. Furthermore, the apoptotic effect for derivatives 5d and 7c in KM12 cells was detected using annexin V-FITC staining method.

Keywords: Apoptosis; Cytotoxicity; Pyrazolopyrimidine hybrids; Pyrimidine based hybrids.