Conversion of allyl alcohol into acrolein by rat liver

1. Acrolein was detected in rat liver suspensions incubated in the presence of allyl alcohol and allyl formate. Acrolein was determined by condensation of the distilled aldehyde with semicarbazide, followed by spectrophotometric measurement of the semicarbazone at 257nm and identification by paper chromatography. 2. The transformation of allyl alcohol into acrolein occurred in the presence of NAD(+). Inhibitors of rat liver alcohol dehydrogenase inhibited the reaction. 3. It is suggested that the hepatotoxic actions of allyl alcohol and of allyl formate on rat liver are related to their conversion into acrolein.     

Formation of mercapturic acids in rats after the administration of aralkyl esters

1. Benzylmercapturic acid and hippuric acid were isolated from the urine of rats that had been injected subcutaneously with benzyl acetate. 2. 1-Menaphthylmercapturic acid and 1-naphthoic acid were isolated from the urine of rats after the subcutaneous injection of each of the following compounds: 1-menaphthyl alcohol and its acetate, propionate, butyrate and benzoate esters. 3. A quantitative method for determining 1-menaphthylmercapturic acid in urine was developed and used to measure the excretion of this compound in the urine of rats in the 4-day period after the subcutaneous injection of 1-menaphthyl alcohol and its acetate, propionate, butyrate and benzoate esters. 4. Chromatographic evidence was obtained for the presence of S-(1-menaphthyl)glutathione and S-(1-menaphthyl)-l-cysteine in bile collected from rats with cannulated bile ducts after the animals had been injected subcutaneously with each of the following compounds: S-(1-menaphthyl)glutathione, 1-menaphthyl acetate, propionate and butyrate. 5. Benzylmercapturic acid and 1-menaphthylmercapturic acid were isolated from the urine of rats that had been injected with sodium benzyl sulphate and sodium 1-menaphthyl sulphate respectively.     

Biosynthesis of amino acids from hydrocarbons

Optimum conditions for the growth ofPseudomonas arvilla, a hydrocarbon utiliser, have been studied. The microorganism produced economic cell yield at pH 5.7 and 4% kerosene concentration. C₁₀-C₁₆ hydrocarbons were utilised by the strain. The growth was maximum on n-decane. Supplementation of the hydrocarbon medium with 0.5% glucose stimulated the growth. Glutamic acid 16.0 mg; leucine 9.0 mg; valine 10.0 mg; methionine 2.5 mg; arginine 2.5 mg; histidine 1.0 mg were present in 100 ml of the broth. Cell protein contained leucine 13.69%, isoleucine 4.9%, histidine 4.37%, tryptophan 2.33%, methionine 1.8% and arginine 2.70%.     

Fatty acids, alcohol and fatty acid ethyl esters: Toxic Ca signal generation and pancreatitis

Pancreatitis, a potentially fatal disease in which the pancreas digests itself as well as its surroundings, is a well recognized complication of hyperlipidemia. Fatty acids have toxic effects on pancreatic acinar cells and these are mediated by large sustained elevations of the cytosolic Ca²⁺ concentration. An important component of the effect of fatty acids is due to inhibition of mitochondrial function and subsequent ATP depletion, which reduces the operation of Ca²⁺-activated ATPases in both the endoplasmic reticulum and the plasma membrane. One of the main causes of pancreatitis is alcohol abuse. Whereas the effects of even high alcohol concentrations on isolated pancreatic acinar cells are variable and often small, fatty acid ethyl esters – synthesized by combination of alcohol and fatty acids – consistently evoke major Ca²⁺ release from intracellular stores, subsequently opening Ca²⁺ entry channels in the plasma membrane. The crucial trigger for pancreatic autodigestion is intracellular trypsin activation. Although there is still uncertainty about the exact molecular mechanism by which this Ca²⁺-dependent process occurs, progress has been made in identifying a subcellular compartment – namely acid post-exocytotic endocytic vacuoles – in which this activation takes place.     

Synthesis and relative stereochemistry of the four mercapturic acids derived from styrene oxide and N-acetylcysteine

The chemical reaction between (±)-styrene oxide and N-acetylcysteine produces both positional isomers ($\text{1}$ and $\text{2}$) as a mixture of diastereoisomers with a preference for the benzylic thioether isomer $\text{1}$ (2 : 1). Synthesis of the mercapturic acid conjugates from either (+)- or (?)-styrene oxide produces only two of the four possible stereoisomers. The single diastereoisomers of $\text{1}$ and $\text{2}$ were separated by high pressure liquid chromatography (HPLC) and identified by ¹H- and ¹³C-nuclear magnetic resonance (NMR). The relative stereochemistry at the benzylic carbon center of the mercapturic acid conjugates was assigned on the basis of the established chemical correlation between optically pure styrene oxide and its precursor mandelic acid, and considerations on the mechanism of ring opening of epoxides by sulfur nucleophiles. The stereochemical definition of the isomers $\text{3}$–$\text{6}$ should prove useful in investigations of the biotransformation of the glutathione (GSH) conjugates of styrene oxide.     

Fatty acids and esters from Panax pseudo-ginseng rhizomes

In addition to methyl palmitate, palmitic acid, stearic acid, eicosanoic acid, triacontanoic acid, hexatriacontanoic acid, pentatriacontane, sitosterol and sitosterol-β-D-glucoside, two new compounds isolated from the rhizomes of Panax pseudo-ginseng have been characterized as 14-hydroxyheneicosanoic acid and dotriacontanyl palmitate, respectively, by physico-chemical studies.     

Biosynthesis of l-tyrosine O-sulphate from the methyl and ethyl esters of l-tyrosine

1. Rat-liver supernatant preparations are capable of achieving the biological sulphation of l-tyrosine methyl ester, the reaction proceeding maximally at a substrate concentration of 30 mm and at pH 7·0. 2. Two sulphated products are formed, one of which has been identified as l-tyrosine O-sulphate. On the basis of indirect evidence the other product can be assumed to be l-tyrosine O-sulphate methyl ester. 3. An enzyme present in rat-liver supernatant preparations is capable of converting l-tyrosine O-sulphate methyl ester into l-tyrosine O-sulphate. This enzyme is inhibited by l-tyrosine methyl ester. 4. l-Tyrosine ethyl ester also yields two sulphated products when used as an acceptor in the liver sulphating system. One of these has been identified chromatographically as l-tyrosine O-sulphate and the other may be presumed to be l-tyrosine O-sulphate ethyl ester.     

Diterpene esters of aristolochic acids from Aristolochia pubescens

From the acetone and ethanol extracts of the tubercula of Aristolochia pubescens, two diterpene esters of aristolochic acids were isolated, together with 23 known compounds. The structures of the compounds were determined on the basis of spectroscopic analysis.     

Biosynthesis of bakuchiol from cinnamic and p-coumaric acids

Specific incorporation of l-[U-¹⁴C]phenylalanine, [U-¹⁴C]cinnamic acid and p[2-¹⁴C]coumaric acid into bakuchiol has been observed in Psoralea corylifolia. Our findings show that the aromatic moiety along with two carbon atoms of the side chain are biosynthetically derived via phenylpropane pathway and not by the alternate pathway proposed earlier.