title: Synthesis and evaluation of N-nicotinoyl-2-{2-(2-methyl-5-nitroimidazol-1-yl)ethyloxy}-D,L-glycine as a colon-specific prodrug of metronidazole.
abstract: Metronidazole (MTZ) is a drug of choice for protozoal infections such as luminal amoebiasis. We designed and synthesized N-nicotinoyl-2-{2-(2-methyl-5-nitroimidazol-1-yl)ethyloxy}-D,L-glycine (NMG) as a colon-specific prodrug of MTZ. The synthetic yield of NMG was about 34%. The apparent partition coefficient of MTZ was greatly reduced by the chemical modification. While (bio)chemically stable in the contents of the upper intestine, NMG was rapidly cleaved to liberate MTZ on incubation with the cecal contents of rats. MTZ metabolized quickly in the cecal contents at least partly by a microbial nitroreductase, suggesting that the metabolism of MTZ is relevant to its bioactivation leading to amoebicidal action. The systemic absorption, analyzed by the blood concentration and urinary recovery of NMG, was very low after oral administration of NMG. In parallel with this, whereas MTZ disappeared mostly during the transit of the proximal small intestine, a substantial amount of NMG remained in the small intestine moving down to the large intestine where it metabolized rapidly. Moreover, comparing systemic absorption of MTZ after oral administration of NMG or MTZ, NMG markedly reduced the systemic absorption. These results suggest that NMG is a potential colon-specific prodrug of MTZ which improves therapeutic and toxicological properties.
authors.affiliation: Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735, Republic of Korea.
authors.forename: Duksoo
authors.initials: D
authors.lastname: Kim
authors.forename: Sungchae
authors.initials: S
authors.lastname: Hong
authors.forename: Sunhwa
authors.initials: S
authors.lastname: Jung
authors.forename: Yunjin
authors.initials: Y
authors.lastname: Jung
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Kim
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000981:Antiprotozoal Agents / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology; D002432:Cecum / Q000378:metabolism; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D004355:Drug Stability; D005998:Glycine / Q000031:analogs & derivatives; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption / Q000187:drug effects; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008795:Metronidazole / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology; D015394:Molecular Structure; D011355:Prodrugs / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000981:Antiprotozoal Agents; C546319:N-nicotinoyl-2-(2-(2-methyl-5-nitroimidazol-1-yl)ethyloxy)-D,L-glycine; D011355:Prodrugs; D008795:Metronidazole; D005998:Glycine