Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “OSAZONES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

31 records · Page 2Linked to original sources
PubMed1986

Correlation between mechanistic biotransformation and biochemical toxicology of some antihypertensive drugs.

Mechanistic biochemistry (consideration of metabolism in the context of knowledge of contemporary biochemistry) was applied to propanolol (1), hydrochlorothiazide (2), hydralazine (3), and triamterene (4), representative of the main types of anti-hypertensive drugs in common use. Three routes of metabolism, that is, acetylation, generation of free radicals (leading to peroxidation of lipids), and osazone formation were considered in relation to the structures of these drugs. The possibility that acetylation can lead to hepatic toxicity, lipid peroxidation to membrane lesion, and osazone formation to glucose and energy depletion was highlighted. Hydralazine, with its potential for osazone formation and great susceptibility to acetylation and free radical formation, was judged most capable of giving rise to these side effects, in agreement with reported toxicity. Triamterene was judged less susceptible than hydralazine to acetylation and free radical formation, and hydrochlorothiazide even less so. Propanolol is immune to any of these consequences.

Acetylation↗
PubMed1986

Radiolysis of poly(U) in oxygenated solution.

Aqueous N2O/O2-saturated solutions of poly(U) were irradiated at 0 degrees C and the release of unaltered uracil determined. Immediately after irradiation G(uracil release) was 1.5 which increased to a value of 5.3 +/- 0.3 upon heating to 95 degrees C. Thereby all of the organic hydroperoxides (G = 6.8 +/- 0.7) and some of the hydrogen peroxide (G = 1.7 +/- 0.2) was destroyed leaving G(peroxidic material; mainly hydrogen peroxide) = 1.0 +/- 0.7. G(chromophore loss) = 8-11 was measured immediately after irradiation, but no increase was observed upon heating. Addition of iodide destroyed the hydroperoxides and caused immediate base release to rise to G = 4 and further heating brought the value to that observed in the absence of iodide. In contrast, on reducing the hydroperoxides with NaBH4, immediate uracil release rose to only G = 2.8 and no further increase was observed on heating. A major product (G = 2.7) is carbon dioxide. There are also osazone-forming compounds produced (G = 2.7), all of which are originally bound to poly(U). Heating in acid solutions, as is required for this test, releases glycoladehyde-derived osazone (G = 0.8) and further unidentified low molecular weight material (G = 0.9). It is concluded that the primary radicals which cause these lesions are the base OH adduct radicals. In the presence of oxygen these are converted into the corresponding peroxyl radicals which abstract an H atom from the sugar moiety. In the course of this reaction base-hydroperoxides are formed. However, such base hydroperoxides cannot be the only organic hydroperoxides, but some (G congruent to 2.5) sugar-hydroperoxides must be formed as indicated by the increase in base release by the addition of iodide. It is speculated that a sugar-hydroperoxide located at C(3') is reduced by iodide to a carbonyl function at C(3'), a lesion that releases the base, while reduction with NaBH4 reduces it to an alcohol function at C(3') thus preventing base release.

DNA↗
PubMed1998

Separative determination of ascorbic acid analogs contained in mushrooms by high-performance liquid chromatography.

Analogs (6-deoxyascorbic acid, erythroascorbic acid, and associated glycosides) of L-ascorbic acid (AA) contained in mushrooms were allowed to react with hydrazine to form osazones, and the conditions for separative determination by HPLC using a Zorbax SIL column were examined. Separation was started using solvent system 1 (ethylacetate/n-hexane/acetone/acetic acid, 50:50:1:1, v/v) as the mobile phase, and switching after 15 min to solvent system 2 (ethylacetate/acetone/acetic acid, 100:1:1, v/v). Detection was performed by absorbance at 500 nm. Because these analogs showed different formation rates for osazone, calibration curves were prepared for each substance. The recovery rate in the load test was 93-105%. By this method, AA and the analogs contained in eight species of edible mushrooms have been determined. The results revealed that: (1) the main constituents of all mushrooms are AA analogs rather than AA itself; (2) only one species contained AA in a very small amount (2 mumol/kg); (3) the types of AA analogs present differed according to the species of mushrooms, and (4) the total amount of AA analogs was between ca. 100-500 mumol/kg (2-9 mg per 100 g, converted to AA). In addition, a new AA analog was found in Pleurotus ostreatus and identified as 5-O-(alpha-D-xylopyranosyl)-D-erythroascorbic acid in structural analyses by NMR and other methods.

Ascorbic Acid↗
PubMed1977

Compartmentation of redox metabolites in the anterior eye segment?

In bovine corneal epithelium, stroma, and aqueous humor the levels of ascorbic acid (ASC) and dehydroascorbic acid (DHA) were investigated. Two methods were used, the photometric assay with 2,6-dichlorophenolindophenol and the formation of osazone by 2,4-dinitrophenylhydrazine. The ASC levels in the corneal epithelium and aqueous humor were found to be in the millimolar range, the ASC/DHA ratio being about 10. The stromal ASC and DHA levels were much lower, with a ratio of 0.7. ASC and DHA had similar levels and ratios to those of reduced and oxidized glutathione (GSH/GSSG) reported in the literature. In the corneal epithelium the redox ratio of glutathione was higher than that of ascorbic acid. Therefore, glutathione was supposed to reduce dehydroascorbic acid.

Animals↗
PubMed1978

Isolation of methylglyoxal from liver.

Acetaldehyde and methylglyoxal were shown to be present in liver bound to protein. They were isolated in the form of 2,4-dinitrophenylhydrazones and osazones, respectively. The NMR spectrum of pure methylglyoxal was recorded.

Aldehydes↗
PubMed1994

Distribution of ascorbic acid analogs and associated glycosides in mushrooms.

Mushrooms contain reducing substances with chemical properties similar to ascorbic acid (AsA). In this study, the four types of reducing substances contained in Flammulina velutipes (Enokitake), Hypsizigus mamoreus (Bunashimeji), Pholiota nameko (Nameko), and Grifola frondosa (Maitake) were respectively purified, and the structure of each was analyzed using nuclear magnetic resonance (NMR) and other methods. The results confirmed that those substances were AsA analogs and associated glycosides (6-deoxy-AsA, 6-deoxy-5-O-(alpha-D-xylopyranosyl)-AsA, 6-deoxy-5-O-(alpha-D-glucopyranosyl)-AsA, and 5-O-alpha-D-glucopyranosyl-erythro-AsA). These substances were characteristic in that saccharide was bonded with the C-5 of the AsA analogs. Osazones were formed from the reducing substances in 19 kinds of edible mushrooms. Using thin-layer chromatography (TLC), they were developed to examine the distribution of the above reducing substances and AsA. The results showed that at least one of the above compounds was certain to be present in any mushroom; that AsA was present in very small quantities if at all; and that several substances similar to the above compounds were present.

Ascorbic Acid↗