The phosphorylation and subsequent metabolism of 1-aminopropan-2-ol

3: Final Report on the Safety Assessment of Diisopropanolamine, Triisopropanolamine, Isopropanolamine, and Mixed Isopropanolamine

Diisopropanolamine, Triisopropanolamine, Isopropanolamine, and Mixed Isopropanolamine are used as water-soluble emulsifiers and neutralizers in cosmetic products at concentrations up to 1%. In animal studies these ingredients were slightly toxic to practically nontoxic to rats and guinea pigs via acute oral administration. Triisopropanolamine was relatively nontoxic to rats in the two subchronic oral studies. These ingredients were moderate skin irritants for rabbits. All four ingredients, when tested at 100% concentrations, were severe ocular irritants in rabbits. Products containing small amounts (-1%) of Diisopropanolamine or Triisopropanolamine were not ocular irritants in rabbits. The Triisopropanolamine salt was not mutagenic in Aspergillus nidulans. Diisopropanolamine and Isopropanolamine at concentrations of 2% did not induce allergic contact dermatitis or photoallergic dermatitis in humans. Clinical studies on cosmetic products containing no more than 1% Diisopropanolamine or 1.1% Triisopropanolamine were minimal skin irritant and contact sensitizers. It is concluded that Diisopropanolamine, Triisopropanolamine, Isopropanolamine, and Mixed Isopropanolamine are safe as cosmetic ingredients in the present practices of use and concentration. The Isopropanolamines should not be used in products containing N-nitrosating agents.

Influence of a beta-adrenergic agonist on septic shock-induced alterations of phosphatidylcholine metabolism in rat lung

Changes in surfactant function play an important part in the pathogenesis of adult respiratory distress syndrome (ARDS). Since beta-adrenergic agonists have been shown to exert a decisive influence on surfactant secretion, we studied the effect of fenoterol on lung phospholipid metabolism under conditions of experimental sepsis. Fenoterol administered to live rats increased the incorporation of choline into lung tissue by 80% in normal, by 35% in septic animals. It had no comparable effect on palmitate incorporation. It increased the activity of choline kinase in control animals, but had no additional effect on animals with increased values due to sepsis. Phosphotransferase activity diminished during sepsis was stimulated, and phospholipase activity reduced. Fenoterol restored phosphatidylcholine to normal levels in lung tissue and bronchoalveolar lavage and prevented lysophosphatidylcholine generation. Fenoterol also increased the amount of palmitate in phosphatidylcholine from bronchoalveolar lavage in septic animals. The results imply that a beta-adrenergic agonist influences the conditions of lung phospholipid metabolism altered by sepsis towards normal.

Identification of phosphatidyl-1-aminopropane-2-ol in rat liver after administration of 1-aminopropane-2-ol

Phosphatidyl-1-aminopropane-2-ol has been detected in rat liver after intraperitoneal administration of 1-aminopropane-2-ol hydrochloride. The new glycerophospholipid was chromatographically identified by comparison with chemically and enzymatically synthesized phosphatidyl-1-aminopropane-2-ol and by gas-liquid chromatography of the polar group as trifluoroacetyl derivative.

Effects of analogles of ethanolamine and choline on phospholipid metabolism in rat hepatocytes

1. Analogues of ethanolamine and choline were incubated with different labelled precursors of phospholipids and isolated hepatocytes and the effects on phospholipid synthesis were studied. 2. 2-Aminopropan-1-ol and 2-aminobutan-1-ol were the most efficient inhibitors of [(14)C]ethanolamine incorporation into phospholipids, whereas the incorporation of [(3)H]choline was inhibited most extensively by NN-diethylethanolamine and NN-dimethylethanolamine. 3. When the analogues were incubated with [(3)H]glycerol and hepatocytes, the appearance of (3)H in unnatural phospholipids indicated that they were incorporated, at least in part, via CDP-derivatives. The distribution of [(3)H]glycerol among molecular species of phospholipids containing 2-aminopropan-1-ol and 1-aminopropan-2-ol was the same as in phosphatidylethanolamine. In other phospholipid analogues the distribution of (3)H was more similar to that in phosphatidylcholine. 4. NN-Diethylethanolamine stimulated both the conversion of phosphatidylethanolamine into phosphatidylcholine and the incorporation of [Me-(14)C]methionine into phospholipids. Other N-alkyl- or NN-dialkyl-ethanolamines also stimulated [(14)C]methionine incorporation, but inhibited the conversion of phosphatidylethanolamine into phosphatidylcholine. This indicates that phosphatidyl-NN-diethylethanolamine is a poor methyl acceptor, in contrast with other N-alkylated phosphatidylethanolamines. 5. These results on the regulation of phospholipid metabolism in intact cells are discussed with respect to the possible control points. They also provide guidelines for future experiments on the manipulation of phospholipid polar-headgroup composition in primary cultures of hepatocytes.

Incorporation and subcellular distribution of an unnatural phospholipid base-analog, N-isopropyl-ethanolamine, in rat liver

An unnatural phospholipid, phosphatidyl-N-isopropylethanolamine, was isolated from rat liver after intraperitoneal injections of N-isopropylethanol-amine; it was identified on the basis of enzymic, chemical, and chromatographic analyses. Although this phospholipid was formed at the expense of phosphatidylcholine and phosphatidylethanolamine, its fatty acid composition did not resemble either of these lipids. Microsomes, mitochondria, and plasma membranes contained significant amounts (up to 9%) of this unusual phospholipid. Radioisotope incorporation experiments suggest that the N-isopropylethanol-amine containing phospholipid is rapidly equilibrated between microsomes and mitochondria and more slowly with surface membranes.