scholarly journals Inhibitory Effects of Ruta graveolens L. Extract on Guinea Pig Liver Aldehyde Oxidase

2006 ◽  
Vol 54 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Pirouzpanah Saieed ◽  
Rashidi Mohammad Reza ◽  
Delazar Abbas ◽  
Razavieh Seyyedvali ◽  
Hamidi Aliasghar
Keyword(s):  
Guinea Pig ◽  
Aldehyde Oxidase ◽  
Ruta Graveolens ◽  
Inhibitory Effects ◽  
Pig Liver ◽  
Guinea Pig Liver

Phenylacetaldehyde Oxidation by Freshly Prepared and Cryopreserved Guinea Pig Liver Slices: The Role of Aldehyde Oxidase

2005 ◽  
Vol 24 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Georgios I. Panoutsopoulos
Keyword(s):  
Guinea Pig ◽  
Xanthine Oxidase ◽  
Aldehyde Dehydrogenase ◽  
Phenylacetic Acid ◽  
Aldehyde Oxidase ◽  
Acid Formation ◽  
Pig Liver ◽  
Liver Slices ◽  
Inhibited Acid ◽  
Guinea Pig Liver

Phenylacetaldehyde is formed when the xenobiotic and biogenic amine 2-phenylethylamine is inactivated by a monoamine oxidase–catalyzed oxidative deamination. Exogenous phenylacetaldehyde is found in certain foodstuffs such as honey, cheese, tomatoes, and wines. 2-Phenylethylamine can trigger migraine attacks in susceptible individuals and can become fairly toxic at high intakes from foods. It may also function as a potentiator that enhances the toxicity of histamine and tyramine. The present investigation examines the metabolism of phenylacetaldehyde to phenylacetic acid in freshly prepared and in cryopreserved guinea pig liver slices. In addition, it compares the relative contribution of aldehyde oxidase, xanthine oxidase, and aldehyde dehydrogenase in the oxidation of phenylacetaldehyde using specific inhibitors for each oxidizing enzyme. The inhibitors used were isovanillin for aldehyde oxidase, allopurinol for xanthine oxidase, and disulfiram for aldehyde dehydrogenase. In freshly prepared liver slices, phenylacetaldehyde was converted mainly to phenylacetic acid, with traces of 2-phenylethanol being present. Disulfiram inhibited phenylacetic acid formation by 80% to 85%, whereas isovanillin inhibited acid formation to a lesser extent (50% to 55%) and allopurinol had little or no effect. In cryopreserved liver slices, phenylacetic acid was also the main metabolite, whereas the 2-phenylethanol production was more pronounced than that in freshly prepared liver slices. Isovanillin inhibited phenylacetic acid formation by 85%, whereas disulfiram inhibited acid formation to a lesser extent (55% to 60%) and allopurinol had no effect. The results in this study have shown that, in freshly prepared and cryopreserved liver slices, phenylacetaldehyde is converted to phenylacetic acid by both aldehyde dehydrogenase and aldehyde oxidase, with no contribution from xanthine oxidase. Therefore, aldehyde dehydrogenase is not the only enzyme responsible in the metabolism of phenylacetaldehyde, but aldehyde oxidase may also be important and thus its role should not be ignored.

THE FORMATION OF ACETOACETATE FROM ACETYL COENZYME A, MALONYL COENZYME A, AND PYRUVATE BY WASHED MITOCHONDRIA ISOLATED FROM GUINEA PIG LIVER

1963 ◽  
Vol 41 (1) ◽  
pp. 1997-2011
Author(s):  
F. Sauer
Keyword(s):  
Guinea Pig ◽  
Coenzyme A ◽  
Inhibitory Effects ◽  
Significant Extent ◽  
Acetyl Coa ◽  
Pig Liver ◽  
Malonyl Coa ◽  
Binding Agents ◽  
Guinea Pig Liver ◽  
Tracer Experiments

Washed mitochondria isolated from guinea pig liver were capable of synthesizing acetoacetate from pyruvate. Both acetyl-CoA and malonyl-CoA were incorporated into acetoacetate in the presence of pyruvate. However, without pyruvate, only acetyl-CoA was incorporated to any significant extent. Tracer experiments indicated that although malonyl-CoA was incorporated into acetoacetate, increased acetoacetate synthesis in the presence of pyruvate plus malonyl-CoA resulted primarily from increased pyruvate incorporation.The results of the present experiments indicated that a CO2fixation step was involved in the conversion of pyruvate to acetoacetate. Evidence in favor of this was based on the inhibitory effects of avidin (with partial reversal by biotin), stimulation with increasing bicarbonate concentration, and increased acetoacetate synthesis in the presence of malonyl-CoA.Sulphydryl binding agents completely inhibited acetoacetate synthesis from pyruvate. In the formation of acetoacetate, carbon atom 1 of pyruvate was eliminated. This indicated that pyruvate was converted into an active 2-carbon unit.

THE FORMATION OF ACETOACETATE FROM ACETYL COENZYME A, MALONYL COENZYME A, AND PYRUVATE BY WASHED MITOCHONDRIA ISOLATED FROM GUINEA PIG LIVER

1963 ◽  
Vol 41 (9) ◽  
pp. 1997-2011
Author(s):  
F. Sauer
Keyword(s):  
Guinea Pig ◽  
Coenzyme A ◽  
Inhibitory Effects ◽  
Significant Extent ◽  
Acetyl Coa ◽  
Pig Liver ◽  
Malonyl Coa ◽  
Binding Agents ◽  
Guinea Pig Liver ◽  
Tracer Experiments

Washed mitochondria isolated from guinea pig liver were capable of synthesizing acetoacetate from pyruvate. Both acetyl-CoA and malonyl-CoA were incorporated into acetoacetate in the presence of pyruvate. However, without pyruvate, only acetyl-CoA was incorporated to any significant extent. Tracer experiments indicated that although malonyl-CoA was incorporated into acetoacetate, increased acetoacetate synthesis in the presence of pyruvate plus malonyl-CoA resulted primarily from increased pyruvate incorporation.The results of the present experiments indicated that a CO2fixation step was involved in the conversion of pyruvate to acetoacetate. Evidence in favor of this was based on the inhibitory effects of avidin (with partial reversal by biotin), stimulation with increasing bicarbonate concentration, and increased acetoacetate synthesis in the presence of malonyl-CoA.Sulphydryl binding agents completely inhibited acetoacetate synthesis from pyruvate. In the formation of acetoacetate, carbon atom 1 of pyruvate was eliminated. This indicated that pyruvate was converted into an active 2-carbon unit.

scholarly journals Simultaneous formation of 2- and 4-quinolones from quinolinium cations catalysed by aldehyde oxidase

1984 ◽  
Vol 220 (1) ◽  
pp. 67-74 ◽  
Author(s):  
S M Taylor ◽  
C Stubley-Beedham ◽  
J G P Stell
Keyword(s):  
Guinea Pig ◽  
Aldehyde Oxidase ◽  
Oxidation Products ◽  
Pig Liver ◽  
Simultaneous Formation ◽  
Ph Values ◽  
Quaternary Compounds ◽  
Guinea Pig Liver ◽  
Quinolinium Salts

Quinolinium salts were incubated with partially purified aldehyde oxidase, and the products were separated by high-pressure liquid chromatography and fully characterized by u.v. spectroscopy, i.r. spectroscopy and mass spectrometry. Oxidation of N-methylquinolinium salts with either rabbit or guinea-pig liver aldehyde oxidase in vitro gave two isomeric products, N-methyl-4-quinolone and N-methyl-2-quinolone. Incubation of N-phenylquinolinium perchlorate similarly yielded two oxidation products, N-phenyl-4-quinolone and N-phenyl-2-quinolone. The ratio of 2- to 4-quinolone production was species-dependent, the proportion of 4-quinolone with the guinea-pig enzyme being greater than that obtained with the rabbit liver enzyme. Kinetic constants were determined spectrophotometrically for both the quinolinium salts and a number of related quaternary compounds. In general, quaternization facilitated oxidation of a substrate, but a number of exceptions were noted, e.g. N-methylisoquinolinium and N-methylphen-anthridinium. Km values varied with the nature of electron acceptor employed, and this difference was more marked for quaternary substrates than the unquaternized counterparts. The product ratio obtained from N-methylquinolinium salts was found to be constant under various conditions, including purification of the enzyme and the use of either induced or inhibited aldehyde oxidase, but a change in the ratio was found at high pH values and in the presence of a competing substrate, N-methylphenanthridinium. This may indicate that a quaternary substrate binds to aldehyde oxidase in two alternative positions.

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