PubMed Health⌕ Search

Biomedical subjects

Slovenko Polanc

Publications and source records attributed to Slovenko Polanc.

6 recordsLinked to original sources
PubMed2003

Diels-Alder reactions of fused pyran-2-ones with maleimides: efficient syntheses of benz[e]isoindoles and related systems.

[reaction: see text] The Diels-Alder reaction of some substituted 5,6,7,8-tetrahydro-2H-1-benzopyran-2-ones (1a-f) with N-substituted maleimides (2a-c) leading to fused isoindole derivatives (5a-n, 7) or, in a few cases, to bridged double cycloadducts (fused bicyclo[2.2.2]octene derivatives) (6a-f) is presented. When X = CO, the first efficient, substituent-driven aromatization of an intermediary-formed cycloadduct was observed, resulting in substituted benz[e]isoindoles (5a-k). The same type of aromatization can also be achieved in an unprecedented catalysis with Rh/C.

Journal Article↗
PubMed2003

D-Gulonolactone as a synthon for L-noviose: first preparation of 4-O-demethyl-L-noviofuranose and related derivatives.

[reaction: see text] A new synthesis of L-noviose (11), a sugar moiety of novobiocin, is presented. D-Gulonolactone was initially converted in a few steps to the key ester derivative 7 [1-O-benzyl methyl 2,3-O-(1-methylethylidene)-alpha-L-lyxofuranosiduronate]. An appropriate selection of protecting groups enabled transformation of 7 under mild reaction conditions to 4-O-demethyl-L-noviofuranose 9a and related 9b-c. Derivatives 9 were further converted either to L-lyxopyranoses (10a and 10b) or to methyl L-lyxofuranoside 12.

Furans↗
PubMed2002

Diazenecarboxamide UP-91, a potential anticancer agent, acts by reducing cellular glutathione content.

Glutathione (GSH) is a ubiquitous non-protein thiol essential for cellular homeostasis and protection. Diazenecarboxamides (diazenes) are new compounds that could, according to their biochemical properties, lower the intracellular GSH content, thus inhibiting the growth of tumour cells. In the present study we examined four such compounds: JK-914, JK-918, JK-1013 and UP-91. Their cytotoxic effect on the growth of eight human tumour cell lines (glioblastoma, cervical and laryngeal carcinoma cells, mammary carcinoma cells and four drug-resistant sublines) was determined using a modified colorimetric MTT assay. The rate of reaction of thiophenol (as a model thiol) with diazenes leading to diphenyl disulfide was established by chromatography (TLC). Reactivity of diazenes with GSH under quasi-physiological conditions was determined by NMR spectroscopy. Intracellular GSH content was examined spectrophotometrically by the procedure developed by Tietze (1969). Diazene UP-91 reduced significantly the cell survival of all eight examined cell lines, including four drug-resistant cell lines. Other diazenes did not influence the survival of tumour cells. Reaction time for quantitative conversion of thiophenol to diphenyl disulfide was shortest for diazene UP-91, which is highly consistent with high reactivity of the same diazene with GSH, observed under quasi-physiological conditions. UP-91 reduced intracellular GSH level, while other diazenes had no effect on it. Thus, diazenecarboxamides UP-91 is a potential anticancer agent that may inhibit the growth of tumour cells due to reduction in glutathione level.

Antineoplastic Agents↗
PubMed2002

Cytotoxic effects of diazenes on tumor cells in vitro.

BACKGROUND: We have shown previously that diazenecarboxamides (diazenes) were cytotoxic for several tumor cell lines. Their target seems to be the intracellular glutathione (GSH). To improve the solubility and biological activity of these drugs, new compounds have been synthesized. In the present study we examined the cytotoxic effect of six new diazenes: BR-25, UP-39, UP-11, JK-1024, RL-514 and RL-625. METHODS: The cytotoxicity of diazenes was tested on nine human tumor cell lines: laryngeal carcinoma HEp2 cells, cervical carcinoma HeLa cells, mammary carcinoma MCF-7 cells, breast adenocarcinoma SK-BR-3 cells, and glioblastoma A1235 cells and their four drug-resistant cell lines. Cytotoxicity was determined using the colorimetric MTT assay. The intracellular GSH content (following the treatment with diazenes) was examined spectrophotometrically in human cervical carcinoma cells by the procedure developed by Tietze. RESULTS: Results show that diazene UP-39 was mostly efficient, significantly reducing the cell survival of all nine cell lines examined, including four drug-resistant cell lines. Diazenes UP-11, RL-514 and BR-25 given in the highest concentrations decreased the survival of some examined cell lines, but to less than 50%. Diazenes RL-625 and JK-1024 had no influence on the cell survival. None of the examined diazenes significantly influenced the intracellular level of GSH. CONCLUSION: Our results suggest that diazene UP-39 may be a promising new drug for the treatment of tumors and encourage further research on this compound.

Antineoplastic Agents↗
PubMed1997

Nitrosation with Sodium Hexanitrocobaltate(III).

Na(3)Co(NO(2))(6) has been investigated as a new reagent for the nitrosation of various substrates containing an amino functionality. Reactions took place in an aqueous solution of the reagent. The pH of the reaction mixture remained in the range 4.3-5. Thus, hydrazides were transformed to the corresponding acyl azides, and the reactions with arenesulfonyl hydrazines afforded arenesulfonyl azides. Treatment of aromatic amines with Na(3)Co(NO(2))(6) gave 1,3-diaryltriazenes in excellent yields; coupling of the initially formed diazo compound to the electron rich aromatic ring was also observed. Nitrosation of aliphatic amines was not possible due to complex formation with the reagent.

Journal Article↗