During biosynthesis of bile acid, carbons 25-26-27 are removed from the cholesterol side-chain. Side-chain oxidation begins either with hydroxylation at the 26-position, in which case the three-carbon fragment is released as propionic acid, or with hydroxylation at the 25-position, in which case the threecarbon fragment is released as acetone. We have previously shown in the rat that the contri...

Acetone is activated by aerobic and nitrate-reducing bacteria via an ATP-dependent carboxylation reaction to form acetoacetate as the first reaction product. In the activation of acetone by sulfate-reducing bacteria, acetoacetate has not been found to be an intermediate. Here, we present evidence of a carbonylation reaction as the initial step in the activation of acetone by the strictly anaero...

Lipid peroxidation is one of the most important sources of endogenous toxic metabolites. 4-Hydroxy-2-nonenal (HNE) and 4-hydroxy-2-hexenal (HHE) are produced in several oxidative stress associated diseases from peroxidation of n-6 and n-3 polyunsaturated fatty acids, respectively. Both are able to form covalent adducts with many biomolecules. Particularly, proteins adduction can induce structur...

The rat adrenal gland secretes a Porter-Silber chromogen with a mobility of 0.6 relative to corticosterone in toluene-propylene glycol (l-3) .I It does not reduce tetrazolium derivatives and differs in this respect from steroids containing a dihydroxyacetone side chain, which reduce tetraeolium, and from the 20keto-21 aldehydes which do not reduce tetrazolium but react more rapidly with the Por...

The aim of this research was to develop a simple procedure for a highly sensitive determination of low-molecular-weight (LMW) carbonyl compounds in drinking water and natural water. We employed a preconcentration HPLC system with 2,4-dinitrophenylhydrazine (DNPH) for the determination of LMW carbonyl compounds. A C-18 reverse-phase preconcentration column was used instead of a sample loop at th...

Milk is among the food more consumed by humanity. In this way, a study of its physical-chemical characteristics justified to analyze if components are legislation and hygiene conditions, precisely use formaldehyde as preservative, established. The International Agency for Research on Cancer warns that has physicochemical properties make it carcinogenic when in food. Brazil, does not establish m...

Two main methods are in current use for the estimation of dehydroascorbic acid. In the one, developed by Roe and his colleagues (Roe & Kuether, 1943; Roe, Mills, Oesterling & Damron, 1948), the dehydroascorbic acid is condensed with 2:4-dinitrophenylhydrazine and the product treated with sulphuric acid to give a red colour, the intensity of which is measured photoelectrically. In a second techn...

Present techniques for the estimation of platelet ascorbic acid allow interference by other substances in the sample. A new and more specific method of analysis is presented. The proposed method owes its increased specificity to resolution of the extract by thin-layer chromatography. By this means ascorbic acid is separated from other reducing substances present. The separated ascorbic acid is ...