Improved chemical syntheses of 5,6-dihydro-5-fluorouracil

Dihydrofolate reductase, thymidylate synthase, and serine hydroxy methyltransferase: successful targets against some infectious diseases

Parasitic diseases have a serious impact on the world in terms of health and economics and are responsible for worldwide mortality and morbidity. The present review features the hybrid targeting involving three main enzymes for the treatment of different parasitic diseases. The enzymes Dihydrofolate reductase, thymidylate synthase, and Serine hydroxy methyltransferase play an essential role in the folate pathway. The present review focuses on these enzymes, which can be targeted against several diseases. It shed light on the past, present, and future of these targets, and it can be assessed that these targets can play a significant role against several infectious diseases. For combating viral and protozoal infectious diseases, these targets in combination should be addressed.

Metabolic Disposition and Elimination of Cyadox in Pigs, Chickens, Carp, and Rats

The metabolism, distribution, and elimination of cyadox (CYA) is investigated in pigs, chickens, carp, and rats to identify the marker residue and target tissue of CYA in food animals for food safety concerns. Following a single oral gavage of [(3)H]-CYA, the total radioactivity was rapidly excreted, with more than 95% of the dose excreted within 14 days in the four species. Fecal excretion of the total radioactivity was 66.2% and 51.6%, and urinary excretion of the total radioactivity was 28.35% and 44.3% in rats and pigs, respectively. Radioactivity was observed in nearly all of the tissues in the first 6 h after 7 days of consecutive oral dosing. The highest radioactivity and longest persistence were in the livers and kidneys, where the majority of the radioactivity was cleared within 7 days. A total of 15 metabolites were identified in rats, pigs, chickens, and carp, and eight new metabolites were identified for the first time in vivo. No parent drug could be detected in the tissues of rats and pigs. The major metabolites of CYA were Cy1, Cy3, and Cy6 in pigs, Cy1, Cy5, and Cy6 in chickens, Cy1, Cy2, and Cy4 in carp, and Cy1, Cy2, Cy4, and Cy5 in rats. Cy1 was suggested to be the marker residue, and the kidneys were identified as the target tissue of CYA in pigs and chickens. These results provide comprehensive information for the food safety evaluation of CYA in food animals and will improve the understanding of the pharmacology and toxicology of CYA in animals.

Dehydrogenative alkenylation of uracils via palladium-catalyzed regioselective C-H activation

A regioselective Pd-catalyzed cross-dehydrogenative coupling between uracils and alkenes is reported. This protocol provides easy access to a variety of 5-alkenyluracil structural motifs.

Metabolism of cyadox by the intestinal mucosa microsomes and gut flora of swine, and identification of metabolites by high-performance liquid chromatography combined with ion trap/time-of-flight mass spectrometry

Cyadox (CYX), 2-formylquinoxaline-1,4-dioxide cyanoacetylhydrazone, is an antimicrobial and growth-promoting feed additive for food-producing animals. To reveal biotransformation of CYX in swine intestine, CYX was incubated with swine intestinal microsomes and mucosa in the presence of an NADPH-generating system and swine ileal flora and colonic flora, respectively. The metabolites of CYX were identified using high-performance liquid chromatography combined with ion trap/time-of-flight mass spectrometry (LC/MS-ITTOF). Structural elucidation of the metabolites was precisely performed by comparing their changes in molecular mass, full scan MS/MS spectra and accurate mass measurements with those of the parent drug. Finally, seven metabolites were identified as follows: three reduced metabolites (cyadox 1-monoxide (Cy1), cyadox 4-monoxide (Cy2) and bisdesoxycyadox (Cy4)); hydroxylation metabolite (3-hydroxylcyadox 1-monoxide (Cy3)); hydrolysis metabolite of the amide bond (N-decyanoacetyl cyadox (Cy5)); a hydrogenation metabolite (11,12-dihydro-bisdesoxycyadox (Cy6)) and a side-chain cleavage metabolite (2-hydromethylquinoxaline (Cy7)). Only one metabolite (Cy1) was found in intestinal microsomes. Cy1, Cy2 and Cy4 were detected in intestinal mucosa, ileal and colonic flora. In addition, Cy3 and Cy5 were only obtained from ileal flora, and Cy6 and Cy7 alone were observed in colonic bacteria. The results indicated that N→O group reduction was the main metabolic pathway of CYX metabolism in swine ileal flora, intestinal microsomes and mucosa. New metabolic profiles of hydrogenation and cleavage on the side chain were found in colonic bacteria. Among the identified metabolites, two new metabolites (Cy6, Cy7) were detected for the first time. These studies will contribute to clarify comprehensively the metabolism of CYX in animals, and provide evidence to explain the pharmacology and toxicology effects of CYX in animals.