Inhibition of bovine dihydrofolate reductase and enhancement of methotrexate sensitivity by N4-(2-acetoxyethoxymethyl)-2-acetylpyridine thiosemicarbazone.

N4-(2-Acetoxyethoxymethyl)-2-acetylpyridine thiosemicarbazone (AATSC) belongs to a series of molecules known to have broad antimicrobial inhibitory activity. These molecules contain the 2-acetoxyethoxy moiety which could conceivably take up a conformation analogous to that of the ribosyl group. Moreover, the thiosemicarbazone moiety, when in the presence of a suitable enzymatic site, could mimic the triazine group, which is found in a number of antifolate drugs. AATSC, which has both bacterial inhibitory activity and water solubility, was accordingly evaluated for its antifolate activity against the bovine liver dihydrofolate reductase. AATSC is shown to be a fully uncompetitive inhibitor of that enzyme. Furthermore, AATSC enhances the activity of methotrexate. Such a potentiation could be useful for therapeutic purposes.

Relationship between azo dye structure and rat hepatic azoreductase activity.

The rate of reduction was determined for a variety of azo dyes using the rat hepatic azoreductase enzyme system. In decreasing order, the rates of reduction for the azo dyes expressed as nmol of arylamine product formed/min/0.25 g of liver were amaranth (33.2), azosulfamide (32.5), orange G (12.4), 1,2-dimethyl-4-p-(carboxyphenylazo)-5-hydroxybenzene (CPA) (9.27), brilliant crystal scarlet (8.00), sulfachrysoidine (7.27), and Sudan I (1.03). A comparison of the partition coefficient with its rate of reduction indicated that the water-soluble azo dyes were reduced more rapidly than the lipid-soluble ones. Furthermore, higher rates of reduction were observed for those dyes containing electron-withdrawing groups on the aromatic rings.

Synthesis and antimicrobial activities of N4-(2-acetoxyethoxymethyl)thiosemicarbazones and N3-(2-acetoxyethoxymethyl)thioureas.

A series of thiosemicarbazones and thioureas having an open-chain analogue of the ribosyl group, the 2-acetoxyethoxymethyl moiety, has been synthesized. Significant growth inhibitory activity versus gram-positive and gram-negative organisms, a yeast, and a mold has been found with the 2-acetoxyethoxymethyl derivatives of N-alkyl-, aryl-, and heteroaryl-thiosemicarbazones and thioureas. The molecules may function as inhibitors of ribonucleotide reductase or in utilization of the carbamyl group in pyrimidine biosynthesis.

Identification of metabolites of [1,2,3-(13)C]Propargyl alcohol in mouse urine by (13)C NMR and mass spectrometry and comparison to rat.

Species differences in the metabolism of acetylenic compounds commonly used in the formulation of pharmaceuticals and pesticides have not been investigated. To better understand the in vivo reactivity of this bond, the metabolism of propargyl alcohol (PA), 2-propyn-1-ol, was examined in rats and mice. An earlier study (Banijamali, A. R.; Xu, Y.; Strunk, R. J.; Gay, M. H.; Ellis, M. C.; Putterman, G. J. J. Agric. Food Chem. 1999, 47, 1717-1729) in rats revealed that PA undergoes extensive metabolism primarily via glutathione conjugation. The current research describes the metabolism of PA in CD-1 mice and compares results for the mice to those obtained for rats. [1,2,3-(13)C;2,3-(14)C]PA was administered orally to the mice. Approximately 60% of the dose was excreted in urine by 96 h. Metabolites were identified, directly, in whole urine by 1- and 2-D (13)C NMR and HPLC/MS and by comparison with the available reference compounds. The proposed metabolic pathway involves glucuronide conjugation of PA to form 2-propyn-1-ol-glucuronide as well as oxidation of PA to the proposed intermediate 2-propynal. The aldehyde undergoes conjugation with glutathione followed by further metabolism to yield as final products 3,3-bis[(2-acetylamino-2-carboxyethyl)thio]-1-propanol, 3-[(2-acetylamino-2-carboxyethyl)thio]-3-[(2-amino-2-carboxyethyl)thi o]-1-propanol, 3,3-bis[(2-amino-2-carboxyethyl)thio]-1-propanol, 3-[(2-amino-2-carboxyethyl)thio]-2-propenoic acid, and 3-[(2-formylamino-2-carboxyethyl)thio]-2-propenoic acid. A small portion of 2-propynal is also oxidized to result in the excretion of 2-propynoic acid. On the basis of urinary metabolite data, qualitative and quantitative differences are noted between rats and mice in the formation of the glucuronide conjugate of PA and in the formation of 2-propynoic acid and metabolites derived from glutathione. These metabolites represent further variation on glutathione metabolism following its addition to the carbon-carbon triple bond compared to those described for the rat.

Identification of metabolites of [1,2,3-(13)C]Propargyl alcohol in rat urine by (13)C NMR and mass spectrometry.

Little is known about the metabolism of acetylenic (C&tbd1;C) compounds commonly used in the formulation of pesticides. To better understand the in vivo reactivity of this bond, we examined the metabolism of propargyl alcohol (PA), 2-propyn-1-ol, used extensively in the chemical industry. [1,2,3-(13)C, 2,3-(14)C]PA was administered orally to male Sprague-Dawley rats. Approximately 56% of the dose was excreted in urine by 96 h. Major metabolites were characterized, directly, in the whole urine by one- and two-dimensional (13)C NMR. To determine the complete structures of metabolites of PA, rat urine was also subjected to TLC followed by purification of separated TLC bands on HPLC. The purified metabolites were identified by (13)C NMR and mass spectrometry and by comparison with available synthetic standards. The proposed metabolic pathway involves oxidation of propargyl alcohol to 2-propynoic acid and further detoxification via glutathione conjugation to yield as final products: 3, 3-bis[(2-(acetylamino)-2-carboxyethyl)thio]-1-propanol, 3-(carboxymethylthio)-2-propenoic acid, 3-(methylsulfinyl)-2-(methylthio)-2-propenoic acid, 3-[[2-(acetylamino)-2-carboxyethyl]thio]-3-[(2-amino-2-carboxyethyl)t hio]-1-propanol and 3-[[2-(acetylamino)-2-carboxyethyl]sulfinyl]-3-[2-(acetylamino)-2-car boxyethyl]thio]-1-propanol. These unique metabolites have not been reported previously and represent the first example of multiple glutathione additions to the carbon-carbon triple bond.