The role of cytoplasmic aldehyde dehydrogenase in the metabolism of N-tele-methylhistamine

Effect of Chinese Herbs on Serum Biochemical Parameters, Immunity Indices, Antioxidant Capacity and Metabolomics in Early Weaned Yak Calves

Chinese traditional herbs are used widely as feed supplements to improve the immune response and antioxidant capacity of livestock. Twenty early-weaned 4-month-old yak calves (72.3 ± 3.65 kg) were divided randomly into four groups (n = 5 per group); three groups were provided with supplementary 80 mL/kg DMI of the root water extracts of either Angelica sinensis, Codonopsis pilosula or Glycyrrhiza uralensis, and one group (control) was not provided with a supplement. Compared to control calves, calves consuming the three herbal extracts increased serum concentrations of albumin (ALB) and glutathione peroxidase (GSH-Px), but decreased serum concentrations of free fatty acids (FFAs) and malondialdehyde (MDA) (p < 0.05). Calves consuming A. sinensis decreased (p < 0.05) serum concentration of total cholesterol (TC), and increased (p < 0.05) serum concentration of total proteins (TP). Serum FFA concentrations increased (p = 0.004) linearly with time in the control group, but not in the groups consuming herbs. Serum metabolomic data demonstrated that A. sinensis and C. pilosula regulate mainly amino acid metabolism, while G. uralensis regulates mainly carbon and amino acid metabolism. It was concluded that the three herbal root extracts, as dietary supplements, improved energy and nitrogen metabolism, and enhanced the antioxidant capacity of yak calves.

Participation of aldehyde dehydrogenase in the oxidative deamination pathway of histamine and putrescine

Some guinea pig tissue homogenates have shown the ability to catabolize, in vitro, imidazoloacetaldehyde (ImAAL) and gamma-aminobutyraldehyde (GABAL) via NAD-dependent aldehyde dehydrogenase (ALDH, EC 1.2.1.3). The liver, kidney, small intestine and gastric mucosa are the richest sources of ALDH activity towards ImAAL. The liver, kidney, small intestine and pancreas also show ALDH activity with GABAL as a substrate. All tissues tested have shown low Km and high Km ALDH activity with propionaldehyde as substrate. The guinea pig liver ALDH which is able to oxidize ImAAL and GABAL is located exclusively in the cytoplasm.

Human aldehyde dehydrogenase: metabolism of putrescine and histamine

Imidazoleacetaldehyde and gamma-aminobutyraldehyde, metabolites of histamine and putrescine, respectively, have been shown to be substrates of human liver aldehyde dehydrogenase (EC 1.2.1.3) cytoplasmic (E1) and mitochondrial (E2) isozymes. The Km values at pH 7.4 and 500 microM NAD for imidazoleacetaldehyde and gamma-aminobutyraldehyde for the E1 isozyme are 40 and 800 microM, respectively, and for the E2 isozyme are 50 and 500 microM, respectively. The Km values with gamma-aminobutyraldehyde with both isozymes are high relative to Km values with acetaldehyde (50 microM for E1 and 1 microM for E2). Since activity with both imidazoleacetaldehyde and gamma-aminobutyraldehyde in crude liver homogenates paralleled that of aldehyde dehydrogenase (EC 1.2.1.3) during purification it appears likely that in the human liver this enzyme is responsible for metabolism of both compounds. If this is the case, interaction between metabolism of histamine and putrescine and that of alcohol is likely. Both imidazoleacetaldehyde and gamma-aminobutyraldehyde were synthesized in this laboratory and their stability has been investigated. Procedures for assaying aldehyde dehydrogenase employing synthetic metabolites of histamine and putrescine are provided.

Subcellular distribution of aldehyde dehydrogenase activities in human liver

The subcellular distributions of aldehyde dehydrogenase activities towards acetaldehyde have been determined in wedge-biopsy samples of human liver. A form with Km values of less than 1 microM and 285 microM towards acetaldehyde and NAD+ respectively was present in the mitochondrial fraction. This enzyme had no detectable activity towards N-tele-methylimidazole acetaldehyde, the aldehyde derived from the oxidation of N-tele-methylhistamine. The activity in the cytosol was more sensitive to inhibition by disulfiram and had Km values of 270 microM and 25 microM for acetaldehyde and NAD+, respectively. It was active towards N-tele-methylimidazole acetaldehyde with a Km value of 2.5 microM and a maximum velocity that was 40% of that determined with acetaldehyde. Both these cytosolic activities had alkaline pH optima.