31129-95-0

Eleven kinds of catechin metabolites produced from (?)-epigallocatechin (EGC) and (?)-epigallocatechin gallate (EGCg) by intestinal microbiota were evaluated for inhibitory activity on the proliferation of HeLa cells, which are human cervical cancer cells

New derivatives of Vaccinia H1-related phosphatase (VHR) inhibitor RE12 (5) were designed by replacing the long straight alkyl chain with other hydrophobic functionalities containing two aromatic rings, with the aim of obtaining potent, cell-active inhibitors. We established a direct coupling reaction between tetronic acid derivative and thioimidate to prepare the RE derivatives 6a-6i efficiently. These compounds all showed VHR-inhibitory activity in the presence of 0.001% NP-40, whereas RE12 (5) was inactive under this condition, even at 100 μM. Further structure-activity studies focused on terminal substitution afforded trifluoromethyl derivative 6k (RE176) and nitro derivative 6l (RE177). The IC50 value of 6l in the presence of NP-40 was almost equivalent to that of RE12 (5) in its absence. Compound 6k (RE176) potently inhibited proliferation of HeLa cells.

Anaerobic metabolism of ( - )-epigallocatechin gallate (EGCg) by rat intestinal bacteria was investigated in vitro. First, intestinal bacteria which are capable of hydrolyzing EGCg to ( - )epigallocatechin (EGC) and gallic acid (2) were screened with 169 strains of enteric bacteria. As a result, Enterobacter aerogenes, Raoultella planticola, Klebsiella pneumoniae susp. pneumoniae, and Bifidobacterium longum subsp. infantis were found to hydrolyze EGCg. Subsequent steps of EGCg metabolism are degradation of EGC (1) by intestinal bacteria. Then, EGC was incubated with rat intestinal bacteria in 0.1 M phosphate buffer (pH 7.1) and the degradation products were analyzed with time by HPLC or LC-MS. Further, the products formed from EGC were isolated and identified by LC-MS and NMR analyses. The results revealed that EGC was converted first to 1-(3', 4', 5'-trihydroxyphenyl)-3-(2 , 4 , 6 -trihydroxyphenyl)propan-2-ol (3) by reductive cleavage between 1 and 2 positions of EGC, and subsequently metabolite 3 was converted to 1-(3', 5'-dihydroxyphenyl)-3-(2 , 4 , 6 -trihydroxyphenyl)propan-2-ol (4) followed by the conversion to 5-(3, 5-dihydroxyphenyl)-4-hydroxyvaleric acid (5) by decomposition of the phloroglucinol ring in metabolite 4. This degradation pathway was considered to be the major route of EGCg metabolism in the in vitro study, but two minor routes were also found. In addition to the in vitro experiments, metabolites 3, 4, 5, and 6 were detected as the metabolites after direct injection of EGC into rat cecum. When EGCg was administered orally to the rats, metabolites 4, 5, 6, 11, and 12 were found in the feces. Among the metabolites detected, metabolite 5 was dominant both in the cecal contents and feces. These findings suggested that the metabolic pathway of EGCg found in the in vitro study may be regarded as reflecting its metabolism in vivo.

The biotransformation of (-)-epicatechin 3-O-gallate (1) and related compounds was undertaken using a human fecal suspension. Of fifteen metabolites isolated, four compounds were new, namely, two epimers of 1-(3'- hydroxyphenyl)-3-(2'',4'',6''-trihydroxyphenyl)propan-2-ols (6, 19); 2'',3''- dihydroxyphenoxyl 3-(3',4'-dihydroxyphenyl)propionate (14) and 1-(3',4'- dihydroxyphenyl)-3-(2'',4'',6''-trihydroxyphenyl)propan-2-ol (18). (-)- Epicatechin (2), (-)-epigallocatechin (16) and their 3-O-gallates (1, 17) were extensively metabolized by a human fecal suspension after incubation for 24 h, whereas the gallates (1, 17) resisted any degradation by a rat fecal suspension, even after a prolonged incubation time (48 h), suggesting a difference in metabolic ability between two intestinal bacterial mixtures from different species.

Antibodies have been raised to a 1-benzazepine hapten and the properties of two of the strongly binding clones, designated C3 and C5, as catalysts examined.Neither antibody catalysed the reaction for which they were first generated, electrophilic substitu