ascorbic-acid and cyanuric-acid

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.

Topics: Ascorbic Acid; Cell Line; Crystallography, X-Ray; Cytosine; Cytostatic Agents; Fibroblasts; HeLa Cells; Hep G2 Cells; Humans; Hydrogen Bonding; Inhibitory Concentration 50; MCF-7 Cells; S Phase Cell Cycle Checkpoints; Stereoisomerism; Structure-Activity Relationship; Triazines; Uracil

Every year over 250 million pounds of cyanuric acid (CA) and chlorinated isocyanurates are produced industrially. These compounds are standard ingredients in formulations for household bleaches, industrial cleansers, dishwasher compounds, general sanitizers, and chlorine stabilizers. The method developed for CA using high-performance liquid chromatography (HPLC) with UV detection simplifies and optimizes certain parameters of previous methodologies by effective pH control of the eluent (95% phosphate buffer: 5% methanol, v/v) to the narrow pH range of 7.2-7.4. UV detection was set at the optimum wavelength of 213 nm where the cyanuric ion absorbs strongly. Analysis at the lower pH range of 6.8-7.1 proved inadequate due to CA keto-enol tautomerism, while at pHs of <6.8 there were substantial losses in analytical sensitivity. In contrast, pHs of >7.4 proved more sensitive but their use was rejected because of CA elution at the chromatographic void volume and due to chemical interferences. The complex equilibria of chlorinated isocyanurates and associated species were suppressed by using reductive ascorbic acid to restrict the products to CA. UV, HPLC-UV, and electrospray ionization mass spectrometry techniques were combined to monitor the reactive chlorinated isocyanurates and to support the use of ascorbic acid. The resulting method is reproducible and measures CA in the 0.5-125 mg/L linear concentration range with a method detection limit of 0.05 mg/L in water.

Topics: Ascorbic Acid; Chromatography, High Pressure Liquid; Hydrogen-Ion Concentration; Indicators and Reagents; Oxidation-Reduction; Spectrophotometry, Ultraviolet; Triazines; Water Pollutants