title: Synthesis, structure elucidation and in vitro anticancer activities of novel derivatives of diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinate and ethyl (4-oxo-8-aryl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl)acetate.
abstract: The worked out and optimized synthesis routes and remarkable antitumour activities in vitro of novel polynitrogenated derivatives of diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinate (7-10) and ethyl (4-oxo-8-aryl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl)acetate (11-16) are presented. Small molecules based on the privileged 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-one scaffold (11-16) were obtained with fairly modest to good overall yields by very facile addition reactions of the nucleophilic centred 1-aryl-2-hydrazonoimidazolidine hydroiodides to diethyl acetylenedicarboxylate (DEAD) in the presence of triethylamine (TEA) and a subsequent cyclocondensation of the putative intermediate chain hydrazones. Heterobicyclic products 12 and 14-16 could also be prepared in high overall yields by an effective intramolecular cyclocondensation of the isolated stable and antiproliferative active heterocyclic hydrazones, namely, diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinates (7-10), performed in refluxing DMF. These intermediates are the first products to be formed in the result of an addition of the nucleophilic reactants, namely, 1-aryl-2-hydrazonoimidazolidines of the 1-6 type, bearing the basic nitrogen atom of the hydrazono moiety (N-NH2), to the carbon-carbon triple bond of the highly electrophilic alkyne, that is, DEAD. Molecular structures of the synthesized compounds (7-16) in the DMSO-d6 solutions were verified by (1)H NMR and (13)C NMR spectral data. These were finally confirmed based on the advanced 2D HMBC and HMQC NMR experiments, which were performed for the two representatives (8 and 11) of the two synthesized sets of the bioactive substances. Among the majority of antiproliferative active molecules, the disclosed herein ethyl [4-oxo-8-(3-chlorophenyl)-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetate (14) is proposed as a promising lead structure for the design of novel highly selective antitumour agents because of the distinctly marked lower cytotoxicity towards the primary cell line of normal HSF cells and several-fold higher against cancer cells used. A double fluorochrome mix-staining was performed in order to find out about the possible mode of action by which this novel small heterobicycle reveals remarkable antiproliferative effects in vitro. Taking into account the obtained double staining results, this small molecule was identified as capable of inducing significantly higher levels of necrotic cells in human cancer cell lines (T47D and HeLa) than in normal HSF cells. Furthermore, its cytotoxicity against cells was found to be connected to the predominant induction of necrosis over apoptosis.
authors.affiliation: Chair and Department of Medical Chemistry, Laboratory of Bioorganic Synthesis and Analysis, Medical University, 4A Chodźki Street, 20-093 Lublin, Poland. Electronic address: malgorzata.sztanke@umlub.pl.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Sztanke
authors.forename: Jolanta
authors.initials: J
authors.lastname: Rzymowska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Sztanke
mesh_terms: D000085:Acetates / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy; D013386:Succinates / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D014227:Triazines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000085:Acetates; D000970:Antineoplastic Agents; D013386:Succinates; D014227:Triazines
keywords: A lead structure: ethyl [4-oxo-8-(3-chlorophenyl)-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetate; Annulated 1,2,4-triazinylacetic esters; Antitumour activity; BrdU based immunoassay; Diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinates; Predominant induction of necrosis over apoptosis; Selective cytotoxicity; Selective necrotic effects; Structure elucidation; The privileged 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-one template