Biomedical subjects

W Fedeli

Publications and source records attributed to W Fedeli.

12 recordsLinked to original sources

PubMed1989

N-benzhydryl-tryptamines and 1,1-diphenyl-tetrahydro-beta-carbolines: synthesis, X-ray crystal structure and benzodiazepine receptor affinity.

Several N-benzhydryl-tryptamines and 1,1-diphenyl-tetrahydro-beta-carbolines were synthetized and the requisites for their formation were established. Crystallographic and conformational analyses were carried out on selected compounds and the affinity for the central benzodiazepine receptors was measured.

Animals↗

PubMed1984

Metabolites of microorganisms. 229. Absolute configuration of naphthomycin A determined by X-ray analysis and chemical degradation.

The relative and absolute configurations of naphthomycin A were elucidated by an X-ray structural analysis of a methylation product, 25-O-methylnaphthomycin A iminomethyl ether. The absolute configuration was confirmed by degradation (O3, NaBH4) to (S)-butane-1,2,4-triol.

Anti-Bacterial Agents↗

PubMed1984

X-ray crystal structure of 4-deoxy-3'-bromopyrido[1',2'-1,2]imidazo[5,4-c]rifamycin S.

This paper reports the determination of the X-ray molecular structure of 4-deoxy-3'-bromopyrido[1',2'-1,2]imidazo[5,4-c]rifamycin S, carried out in order to unequivocally define the general structure of a new series of rifamycin SV derivatives, which are potent antibacterial agents, and are not absorbed at the gastroenteric level. They have been prepared by Alfa Farmaceutici, Bologna, by condensing 2-aminopyridine derivatives to 3-bromorifamycin S. The solid state X-ray study has confirmed the structure proposed on the basis of 1H NMR studies in solution. It has also shown that the newly formed pyridoimidazo system is in a mesomeric betaine form, the pyrido nitrogen being positively charged and the imidazo nitrogen being negatively charged. This feature is believed responsible for the pharmacokinetic behavior of these new drugs, one of which, denoted either as rifamycin L 105 or rifaximin, is actually under clinical trial as a topical intestinal disinfectant.

Magnetic Resonance Spectroscopy↗

PubMed1982

Structure-activity relationships in the ansamycins. Molecular structure and activity of 3-carbomethoxy rifamycin S.

The X-ray and NMR structural study of 3-carbomethoxy rifamycin S5 was undertaken in order to determine whether its low antimicrobial activity was related to a conformation of the molecule which was unfavorable for interaction with bacterial DNA-dependent RNA polymerase. However, the molecule assumes a conformation similar to that of the active rifamycins. Indeed the compound was found to be active on the isolated enzyme, so that its low activity on whole bacteria has to be attributed to factors affecting its penetration through the bacterial cell wall.

Anti-Bacterial Agents↗

PubMed1978