1,721,001 research outputs found
Mass spectrometric study of 5,6- and 5,7-dihydroxytryptamines and their biological precursors.
No full textEnzyme activities along the kynurenine pathway in mice
No full textTryptophan metabolism was studied in adult male Swiss mice by determining enzyme activities along the kynurenine pathway. The following enzymes were assayed: liver tryptophan 2,3-dioxygenase, small intestine indole 2,3-dioxygenase, liver and kidney kynurenine 3-monooxygenase, kynureninase, kynurenine-oxoglutarate transaminase, 3-hydroxyanthranilate 3,4-dioxygenase, and aminocarboxymuconate-semialdehyde decarboxylase. Liver tryptophan 2,3-dioxygenase was present only as a holoenzyme: similar results were obtained in the absence or in the presence of the cofactor haematin. The specific activity of small intestine indole 2,3-dioxygenase was higher than that of tryptophan 2,3-dioxygenase. As superoxide dismutase was very active in mouse intestine, this enzyme may be one of the rate controlling factors of the indole 2,3 dioxygenase activity. Kynurenine 3-monooxygenase appeared to be very active. Kidneys showed higher activity than liver. Instead, kynureninase was more active in liver, but activity was lower than that demonstrated by the other enzymes of the kynurenine pathway. Conversely, kynurenine-oxoglutarate transaminase was much more active in kidney than in liver. However, the most active enzyme along the kynurenine pathway was 3-hydroxyanthranilate 3,4-dioxygenase, with liver showing the highest activity; aminocarboxymuconate-semialdehyde decarboxylase, which showed similar values in both liver and kidney, showed activity markedly lower than 3-hydroxyanthranilate 3,4-dioxygenase. Serum tryptophan appeared to be 87% bound to proteins. Results demonstrate that, in mouse, tryptophan is mainly metabolised along the kynurenine pathway. Therefore, mouse is a suitable animal model for studying tryptophan metabolism in the pathological field
An investigation of the aroma fraction of some Italian wines by solid phase micro extraction gas chromatography mass spectrometry and membrane inlet mass spectrometry
No full textTwo analytical approaches have been applied to the characterization of the aroma fraction of five Italian wines, solid-phase micro-extraction coupled with gas chromatography, and membrane inlet mass spectrometry. The first approach resulted in highly specific and reproducible data and permitted the differentiation among wine samples from the same grape but from different production areas. The second technique, notable for its short time of analysis and ease of use, exhibited a lower specificit
Application of matrix-assisted laser desorption/ionization mass spectrometry to the detection of melanins formed from DOPA and dopamine
No full textQuinoa: protein and nonprotein tryptophan in comparison with other cereal and legume flours and bread
No full text• nutritional value of bread can be improved making composite flours with non wheat cereals or supplementing its flour with protein-rich sources, such as legume flours, especially in the several countries where the production of wheat is insufficient;
• quinoa can be an alternative to cereals in the human diet for its nutritional value and high good quality proteins similar to those of milk, and for these reasons, its use should be promoted to enrich the nutritional value of bakery products;
• tryptophan is present in cereals and legumes not only as protein tryptophan but also as non protein tryptophan (Figure 7);
• non protein tryptophan should be taken into account when the nutritional value of a food is determined;
• the determination of non protein tryptophan in cereals and legumes is very important since this fraction is easily absorbable at the gastrointestinal level increasing its availability for brain serotonin synthesis
Tryptophan metabolism along the kynurenine pathway in diet-induced and genetic hypercholesterolemic rabbits
No full textBACKGROUND:
The activity of nicotinic acid in hypercholesterolemia has been poorly understood. In man, nicotinic acid derives for the most part from tryptophan along the tryptophan-nicotinic acid pathway, also called the kynurenine pathway, kynurenine being the key metabolite in this process. In the present paper, we investigated if, in animals with hypercolesterolemia, degradation of tryptophan to nicotinic acid along the kynurenine pathway was perturbated.
METHODS:
Liver, kidney and intestine enzyme activities of the tryptophan-nicotinic acid pathway in normolipidemic, diet-induced hyperlipidemic New Zealand and heritable hypercholesterolemic Watanabe (WHHL) rabbits were determined.
RESULTS:
Liver tryptophan 2,3-dioxygenase (TDO) activity was present only as a holoenzyme and was higher in the controls than in the hyperlipidemic and Watanabe rabbits, but no difference was present between the group fed an atherogenic hyperlipidic diet and the WHHL rabbits. Small intestine indole 2,3-dioxygenase (IDO) did not vary significantly among the three groups but was higher in comparison with liver TDO activity. In liver, kynurenine 3-monooxygenase and kynurenine-oxoglutarate transaminase activities did not show any significant difference among the three groups of rabbits. Kynureninase and 3-hydroxyanthranilate 3,4-dioxygenase activities per g of fresh tissue decreased significantly in the group of hyperlipidemic and in WHHL rabbits. In the kidneys, kynurenine 3-monooxygenase and kynureninase activity did not change significantly in the three groups of rabbits; kynurenine-oxoglutarate transaminase activity per g of fresh tissue decreased in both hyperlipidemic groups, but no significant difference was observed between hyperlipidemic and Watanabe rabbits. 3-Hydroxyanthranilate 3,4-dioxygenase activity in kidney was decreased markedly in hyperlipidemic and Watanabe rabbits, but there was no difference between the two hypercholesterolemic groups. Aminocarboxymuconate-semialdehyde decarboxylase activity did not change. Thus 3-hydroxyanthranilate 3,4-dioxygenase may be an important regulatory mechanism in the control of the flow of tryptophan along the kynurenine pathway to NAD in hypercholesterolemic rabbits.
CONCLUSIONS:
This study first demonstrates that in rabbits, hypercholesterolemia, both diet- or genetically induced, can influence the enzyme activities of the tryptophan-nicotinic acid pathway leading to a decreased formation of nicotinic acid, and thus NAD
Cloricromene effect on the enzyme activities of the tryptophan-nicotinic acid pathway in diabetic/hyperlipidemic rabbits
No full textSince alterations of tryptophan metabolism have been reported in diabetes and atherosclerosis, it was thought of interest to investigate any role of cloricromene through the influence on the oxidative metabolism of the amino acid by using diabetic/hyperlipidemic rabbits. Male 4-month-old New Zealand white rabbits, fed a diet enriched with 1% cholesterol and 10% corn oil, were made diabetic with alloxan. During the hyperlipidemic diet, a group of rabbits was treated with cloricromene (10 mg/kg/day subcutaneously plus 1.5 mg/kg/day intravenously, for 5 weeks). The other group received saline. Normometabolic New Zealand rabbits fed standard diet, treated or not with cloricromene, were used as control. The specific activities of liver tryptophan 2,3-dioxygenase and small intestine indole 2,3-dioxygenase were not significantly changed by the drug treatment. Also the specific activities of other enzymes of the kynurenine pathway in the liver and kidneys, specifically kynurenine 3-monooxygenase, kynureninase and kynurenine-oxoglutarate transaminase, did not show any significant difference in both tissues between the two groups of rabbits. On the contrary, 3-hydroxyanthranilate 3,4-dioxygenase activity in the liver of diabetic/hyperlipidemic rabbits and control rabbits treated with cloricromene showed a slight increase in comparison with untreated animals. Conversely, the specific activity of the enzyme in kidneys was not affected by the drug treatment in diabetic/hyperlipidemic animals but was reduced in controls. Aminocarboxymuconate-semialdehyde decarboxylase specific activity remained unchanged in the liver following cloricromene treatment, instead the specific activity of the enzyme in the kidneys of the diabetic/hyperlipidemic rabbits was significantly increased by the drug, with a value more than double in comparison to untreated animals. The activity of the scavenger enzyme Cu/Zn superoxide dismutase (Cu/Zn SOD) in the small intestine was also determined and found significantly increased of about twice as much in the group of diabetic/hyperlipidemic rabbits treated with cloricromene. In conclusion, in diabetic/hyperlipidemic rabbits, cloricromene appeared to influence the enzymes involved in the last steps of tryptophan oxidative metabolism through the kynurenine pathway. This, together with the antioxidant action through the activation of Cu/Zn SOD, might deserve further investigation for evaluating any link between the observed experimental findings at the level of the kynurenine pathway and the clinical effect of the drug
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