The photodynamic effect in the yeastSaccharomyces cerevisiae sensitized with methylene blue in the presence of various substrates

Деятельность дыхат ельной системы из Saccharomyces cerevisiae снижается в видимом свете в пр исутствии метиленов ого синий только от г олода клеток. Если клетки обладают нек оторые метаболическ ой энергии Фото-окис лительные поврежден ия дыхательных enzymic системы является лишь весьма незначи тельные. Наличие полезной уг леводов, такие, как са хароза, глюкоза или а цетата защищает дых ательной активности клеток из Saccharomyces cerevisiae от Фото-окислительные повреждения. Адаптивно полезной субстрата, например галактозы, не защища ет, не адаптированные Клетки Saccharomyces cerevisiae. Адаптиро ванный клеток, охран яются в соответстви и с галактозы также глюкоза или сахаро за.     

Photooxidation of amino acids in the presence of methylene blue

A systematic study was made of the photochemical action of methylene blue on amino acids.Tyrosine, tryptophan, histidine, methionine, and cystine were highly reactive during the photoöxidation; the rest of the amino acids acted sluggishly or not at all.In tyrosine, tryptophan, and histidine, the entire oxygen uptake and CO₂ evolution were due to the cyclic nucleus, involving rupture of the rings.During the photochemical action of methylene blue on tyrosine, tryptophan, and methionine, intermediary oxidizing agents were formed; in methionine this was shown to be H₂O₂.The photoöxidation of methionine resulted in the formation of methionine sulfoxide as an end product.Iodometric titration and measurement of ultraviolet absorption during irradiation of methionine indicate the formation of an intermediary dehydrogenation product which appears to differ from Lavine's dehydromethionine.Cystine was photoöxidized, probably beyond the cysteic acid stage.Peptide bonds did not participate in the photochemical action of methylene blue.Methylation of the α-amino group of lysine to the corresponding secondary and tertiary compounds produced increased reactivity in the photoöxidation.     

Analysis of methylene blue in human urine by capillary electrophoresis

A capillary electrophoresis method for the determination of the dye methylene blue (tetramethylthionine, MB) in human urine depending on liquid/liquid-extraction and diode array detection has been developed, validated, and applied to samples of healthy individuals, who had been dosed with methylene blue within clinical studies. After extraction with dichloromethane and sodium hexanesulfonate, sample extracts were measured on an extended light path capillary. The dye was detected simultaneously at 292 and 592 nm using methylene violet 3 RAX as internal standard. The limit of quantification was 1.0 microg/ml. The accuracy of the method varied between -15.2 and +0.8% and the precision ranged from 2.0 to 12.0%. The method was linear at least within 1.0 and 60 microg/ml. In contrast to earlier indirect determinations no leuco methylene blue (LMB) was directly detected in urine, whereas in aqueous test solutions containing surplus amounts of ascorbic acid leuco methylene blue was well separated from MB in a single run.