title: The new 5- or 6-azapyrimidine and cyanuric acid derivatives of l-ascorbic acid bearing the free C-5 hydroxy or C-4 amino group at the ethylenic spacer: CD-spectral absolute configuration determination and biological activity evaluations.
abstract: We report on the synthesis of the novel types of cytosine and 5-azacytosine (1-9), uracil and 6-azauracil (13-18) and cyanuric acid (19-22) derivatives of l-ascorbic acid, and on their cytostatic activity evaluation in human malignant tumour cell lines vs. their cytotoxic effects on human normal fibroblasts (WI38). The CD spectra analysis revealed that cytosine (5 and 6), uracil (14-16), 6-azauracil (17) and cyanuric acid (21) derivatives of l-ascorbic acid bearing free amino group at ethylenic spacer existed as a racemic mixture of enantiomers, whereas L-ascorbic derivatives containing the C-5 substituted hydroxy group at the ethylenic spacer were obtained in (4R, 5S) enantiomeric form. The stereochemistry of 6-azauracil derivative of l-ascorbic acid (13) was confirmed by X-ray crystal structure analysis. The molecules are self-assembled by one N-H⋯O hydrogen bond, two C-H⋯O hydrogen bonds and two C-H⋯π interactions into three-dimensional framework. Cytostatic activity evaluation indicated that compounds did not show distinctive antiproliferative effects on tested cell line panel. However, the cytosine derivative of l-ascorbic acid (1) containing the C4-C5 double bond conjugated with the lactone moiety produced rather marked growth inhibitory effect on hepatocellular carcinoma (HepG2), metastatic breast epithelial carcinoma (MCF-7) and cervical carcinoma (HeLa) cell lines at micromolar concentrations, but also exerted strong cytostatic effect on WI38. 5-Azacytosine derivative of l-ascorbic acid (2) with a double bond at the C4-C5 conjugated with the lactone moiety displayed potent antitumour activity against tested tumour cell lines with meanIC(50) values ranging from 0.92 to 5.91 μM. However, this compound also exhibited pronounced cytotoxicity towards WI38. Flow cytometric analysis of the cell cycle revealed that compound 2 triggers S phase arrest, which clearly demonstrates its interference with DNA replication, a key event of cell proliferation. Marked anticancer efficacy of compound 2 supports further in vivo investigation into its possible clinical utility.
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 20, HR-10000 Zagreb, Croatia.
authors.forename: K
authors.initials: K
authors.lastname: Wittine
authors.forename: M Stipković
authors.initials: MS
authors.lastname: Babić
authors.forename: M
authors.initials: M
authors.lastname: Košutić
authors.forename: M
authors.initials: M
authors.lastname: Cetina
authors.forename: K
authors.initials: K
authors.lastname: Rissanen
authors.forename: S Kraljević
authors.initials: SK
authors.lastname: Pavelić
authors.forename: A Tomljenović
authors.initials: AT
authors.lastname: Paravić
authors.forename: M
authors.initials: M
authors.lastname: Sedić
authors.forename: K
authors.initials: K
authors.lastname: Pavelić
authors.forename: M
authors.initials: M
authors.lastname: Mintas
mesh_terms: D001205:Ascorbic Acid / Q000138:chemical synthesis* / Q000494:pharmacology; D002460:Cell Line; D018360:Crystallography, X-Ray; D003596:Cytosine / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000494:pharmacology; D054697:Cytostatic Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D005347:Fibroblasts; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D006860:Hydrogen Bonding; D020128:Inhibitory Concentration 50; D061986:MCF-7 Cells; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014227:Triazines / Q000138:chemical synthesis* / Q000494:pharmacology; D014498:Uracil / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000494:pharmacology
chemical_list: D054697:Cytostatic Agents; D014227:Triazines; D014498:Uracil; D003596:Cytosine; C004632:cyanuric acid; D001205:Ascorbic Acid