RESUMEN
Breast cancer is a common public health disease causing mortality worldwide. Thus, providing novel chemotherapies that tackle breast cancer is of great interest. In this investigation, novel pyrido[2,3-d]pyrimidine derivatives 3,4,(6a-c),(8a,b),9-20 were synthesized and characterized using a variety of spectrum analyses. The geometric and thermal parameters of the novel thiouracil derivatives 3,4,6a,(8a,b),11,12,17,18, 19 were measured using density functional theory (DFT) via DFT/B3LYP/6-31 + G(d,p) basis set. All synthesized compounds were evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) method using MCF-7 and MDA-MB-231 breast cancerous cells, compound 17 had the maximum anticancer activity against both breast cancerous cells, recording the lowest half-maximal inhibitory concentration (IC50) values (56.712 µg/mL for MCF-7 cells and 48.743 µg/mL for MDA-MB-231 cells). The results were confirmed in terms of the intrinsic mechanism of apoptosis, where compound 17 had the highest percentage in the case of both cancer cells and recorded Bax (Bcl-2 associated X)/Bcl-2 (B-cell lymphoma 2) ratio 17.5 and 96.667 for MCF-7 and MDA-MB-231 cells, while compound 19 came after 17 in the ability for induction of apoptosis, where the Bax/Bcl-2 ratio was 15.789 and 44.273 for both cancerous cells, respectively. Also, compound 11 recorded a high Bax/Bcl-2 ratio for both cells. The safety of the synthesized compounds was applied on normal WI-38 cells, showing minimum cytotoxic effect with undetectable IC50. Compounds 17, 11, and 19 recorded a significant increase of p53 upregulated modulator of apoptosis (PUMA) expression levels in the cancerous cells. The DFT method was also used to establish a connection between the experimentally determined values of the present investigated compounds and their predicted quantum chemical parameters. It was concluded that Compounds 17, 11, and 19 had anti-breast cancer potential through the induction of apoptotic Bax/Bcl-2 and PUMA expression levels.