Synthesis and Biological Evaluation of 12-Aryl-11-hydroxy-5,6-dihydropyrrolo[2″,1″:3',4']pyrazino[1',2':1,5]pyrrolo[2,3- d ]pyridazine-8(9 H )-one Derivatives as Potential Cytotoxic Agents.

In the present paper, a facile and efficient synthetic procedure has been applied to obtain dihydrodipyrrolo[1,2- a :2',1'- c ]pyrazine-2,3-dicarboxylates ( 5a - s ), which have subsequently gone through the cyclization in the presence of hydrazine hydrate to afford 12-aryl-11-hydroxy-5,6-dihydropyrrolo[2″,1″:3',4']pyrazino[1',2':1,5]pyrrolo[2,3- d ]pyridazine-8(9 H )-ones ( 7a - q ). The molecular structures of these novel compounds were extensively examined through the analysis of spectroscopic data in combination with X-ray crystallography techniques. Following that, the in vitro cytotoxic activities of all derivatives against three human cancer cell lines (Panc-1, PC3, and MDA-MB-231) were comprehensively evaluated alongside the assessment on normal human dermal fibroblast (HDF) cells using the MTT assay. Among the compounds, the 3-nitrophenyl derivative ( 7m ) from the second series showed the best antiproliferative activity against all tested cell lines, particularly against Panc-1 cell line, (IC 50 = 12.54 μM), being nearly twice as potent as the standard drug etoposide. The induction of apoptosis and sub-G1 cell cycle arrest in Panc-1 cancer cells by compound 7m was confirmed through further assessment. Moreover, the inhibition of kinases and the induction of cellular apoptosis by compound 7m in Panc-1 cancer cells were validated using the Western blotting assay.