ОБНАРУЖЕНИЕ ГИДРОПЕРОКСИДОВ В РАСТВОРАХ ФОТООКИСЛЕННОГО ПСОРАЛЕНА

Photooxidized psoralen solutions possess a variety of biological effects, which implementation mechanism may presumably involve hydroperoxides. Here, the hydroperoxide content in photooxidized psoralen solutions was assessed using photometric FOX assay (from Ferrous Oxidation + Xylenol Orange). FOX reagent with 10× content of Xylenol Orange, modified for quantitative analysis of up to 50 μM of hydroperoxides in aqueous phase was used in experiments. During photooxidation of 0.1 mM psoralen in phosphate buffer solution, hydroperoxide production increases with dose of UVA irradiation (~2.5 μM eq. of H2O2 for dose of 252 kJ/m2 and ~11 μM eq. of H2O2 for dose of 1512 kJ/m2) and reaches ~16.5 μM eq. of H2O2 at the highest dose investigated (3024 kJ/m2). A comparison of kinetics of psoralen photolysis and hydroperoxide generation allows us to suggest that generation of hydroperoxide results from the secondary photochemical processes involving psoralen photoproducts, presumably from photoinduced autooxidation of aldehydic photoproducts of psoralen.Растворы фотоокисленного псоралена обладают целым рядом биологических эффектов, механизм реализации которых предполагает участие в них гидропероксидов. В настоящей работе содержание гидропероксидов в растворах фотоокисленного псоралена оценивали фотометрически методом FOX-анализа (от англ. Ferrous Oxidation + Xylenol Orange). В экспериментах использовали модифицированный FOX-реагент, с 10-кратным содержанием ксиленолового оранжевого, позволяющий количественно обнаруживать в водной фазе до 50 мкМ гидропероксидов. В процессе фотоокисления 0.1 мМ раствора псоралена в фосфатном буферном растворе продукция гидропероксидов растет с увеличением дозы УФ-А-облучения (~2.5 мкМ экв. H2O2 для дозы 252 кДж/м2 и ~11 мкМ экв. H2O2 для дозы 1512 кДж/м2) и достигает ~16.5 мкМ экв. H2O2 в случае максимальной исследованной дозы облучения (3024 кДж/м2). Сравнение кинетики фотолиза псоралена и формирования гидропероксидов позволяет сделать вывод, что генерация гидропероксидов является результатом вторичных фотохимических процессов с участием фотопродуктов псоралена, предположительно, фотоиндуцированного автоокисления фотопродуктов псоралена альдегидной природы

pH-Dependent Photoinduced Interconversion of Furocoumaric and Furocoumarinic Acids

Photo-controlled or photo-regulated molecules, especially biologically active and operating in physiological conditions, are in steady demand. Herein, furocoumaric and furocoumarinic acids being (Z/E)-isomers relative to each other were obtained in two stages starting from psoralen: the alkaline solvolysis of psoralen led to furocoumaric acid, which was further Z → E photoisomerized (365 nm) to furocoumarinic acid. The kinetics of Z → E photoisomerization was monitored by HPLC and UV-vis spectrophotometry. Photophysical characteristics in the aqueous phase for both acids, as well as the reversibility of (Z/E) photoisomerization process, were also assessed. Furocoumarinic acid was found to be visibly fluorescent at pH 2.0–12.0, with the maxima of fluorescence emission spectra being pH-dependent. The reverse E → Z photoisomerization predicted by quantum chemistry calculations as energetically favorable for the monoanionic form of furocoumarinic acid was proved in the experiment while being complicated by pyrone ring closure back to psoralen in acidic and neutral conditions. The preparative synthesis of furocoumarinic acid outlined in this work is particularly valuable in view of a wide range of pharmacological effects previously predicted for this compound

DETECTION OF HYDROPEROXIDES IN SOLUTIONS OF PHOTOOXIDIZED PSORALEN

Photooxidized psoralen solutions possess a variety of biological effects, which implementation mechanism may presumably involve hydroperoxides. Here, the hydroperoxide content in photooxidized psoralen solutions was assessed using photometric FOX assay (from Ferrous Oxidation + Xylenol Orange). FOX reagent with 10× content of Xylenol Orange, modified for quantitative analysis of up to 50 μM of hydroperoxides in aqueous phase was used in experiments. During photooxidation of 0.1 mM psoralen in phosphate buffer solution, hydroperoxide production increases with dose of UVA irradiation (~2.5 μM eq. of H2O2 for dose of 252 kJ/m2 and ~11 μM eq. of H2O2 for dose of 1512 kJ/m2) and reaches ~16.5 μM eq. of H2O2 at the highest dose investigated (3024 kJ/m2). A comparison of kinetics of psoralen photolysis and hydroperoxide generation allows us to suggest that generation of hydroperoxide results from the secondary photochemical processes involving psoralen photoproducts, presumably from photoinduced autooxidation of aldehydic photoproducts of psoralen

Twice as Nice: The Duff Formylation of Umbelliferone Revised

More efficient and preferably more convenient and greener synthetic solutions in coumarin scaffold functionalization are in steady demand. The Duff ortho-formylation of unsubstituted umbelliferone was revised in this study. The reaction conditions were optimized based upon data from the literature analysis and resulted in unexpectedly rapid ortho-formylation of umbelliferone, yielding a mixture of ortho-formyl position isomers. Thorough studies on the separation of ortho-formylated umbelliferones using chromatographic and recrystallization methods as well as the evaluation of their solubility in common organic solvents led to complete resolution of 8-formyl- and 6-formylumbelliferones. The precise protocol for simultaneous preparation, extraction, and purification of 8-formyl- and 6-formylumbelliferones is provided, and the prospective studies of biological and pharmacological activities of these compounds are synopsized

A 2,5-Dihydroxybenzoic Acid–Gelatin Conjugate Inhibits the Basal and Hsp90-Stimulated Migration and Invasion of Tumor Cells

The extracellular cell surface-associated and soluble heat shock protein 90 (Hsp90) is known to participate in the migration and invasion of tumor cells. Earlier, we demonstrated that plasma membrane-associated heparan sulfate proteoglycans (HSPGs) bind the extracellular Hsp90 and thereby promote the Hsp90-mediated motility of tumor cells. Here, we showed that a conjugate of 2,5-dihydroxybenzoic acid with gelatin (2,5-DHBA–gelatin), a synthetic polymer with heparin-like properties, suppressed the basal (unstimulated) migration and invasion of human glioblastoma A-172 and fibrosarcoma HT1080 cells, which was accompanied by the detachment of a fraction of Hsp90 from cell surface HSPGs. The polymeric conjugate also inhibited the migration/invasion of cells stimulated by exogenous soluble native Hsp90, which correlated with the inhibition of the attachment of soluble Hsp90 to cell surface HSPGs. The action of the 2,5-DHBA–gelatin conjugate on the motility of A-172 and HT1080 cells was similar to that of heparin. The results demonstrate a potential of the 2,5-DHBA–gelatin polymer for the development of antimetastatic drugs targeting cell motility and a possible role of extracellular Hsp90 in the suppression of the migration and invasion of tumor cells mediated by the 2,5-DHBA–gelatin conjugate and heparin