3 -Methyl-catechin glucuronide

Methyl catechin glucuronide Methyl catechin sulfate... 

Catechin glucuronide Epicatechin glucuronide Methyl catechin glucuronide Trimer... 

Hackett AM, Shaw IC, Griffiths LA. 3t(9-methyl-(+)-catechin glucuronide and 3t 0-methyl-(+)-catechin sulphate New urinary metabolites of (+)-catechin in the rat and the marmoset. Experimentia 1982 38(5) 538-540. 

Then, different procyanidin metabolites were generated, these being catechin and epicatechin in its glucuronide forms, catechin and epicatechin in its sulfate forms, methyl-catechin and methyl-epicatechin in its glucuronide forms, and methyl-calechin and methyl-epicatechin in its sulfate forms [31-33,35-39], In some studies, the aglycones, catechin, epicatechin, dimer, and trimer were also identified [31,33,35,36]. The main metabolites generated from the procyanidin-rich extract intake are shown in Table 14.3. 

Apart from these in vivo applications, a coculture system on hepatic cells was also reported for assaying the bioactivity of a procyanidin extract. In this report, different procyanidin metabolites were identified, these being catechin and epicatechin in its sulfate forms methyl-catechin and methyl-epicatechin in its sulfate forms epicatechin glucuronide, methyl-catechin, and methyl-epicatechin in its glucuronide forms and the aglycones catechin and epicatechin, epicatechin in its gallate forms, dimer and trimer [38]. 

Kuhnle G, Spencer JPE, Schroeter H, Shenoy B, Debnam E, Srai S, Rice-Evans C, Hahn U. Epicatechin and catechin are O-methylated and glucuronidated in the small intestine. Biochem Biophys Res Commun 2000 277(5) 507-512. 

Within the hver, SULT activity is predominant, but further methylation may also occur. Catechin glucuronides were subsequently sulfated, as well as methylated, in rat hver after in situ perfusion [49]. Piskula and Terao [73] also reported that SULT activity for epicatechin was present exclusively in liver. Within hepatocytes, it is also possible that catechin glucmonides are deglucu-ronidated and then reglucuronidated before reaching systemic circulation [49]. 

Tea flavonoids, or tea extracts, are increasingly being added to foods. However, interactions with food and drink components remain unclear, and thus need to be carefully assessed in order that the full potential benefits from consuming tea, in whatever form, can be achieved. Meanwhile, tea catechins themselves undergo extensive O-methylation, glucuronidation, sulphation and ring fission... 

LC/ESI-MS analyses were applied to determine urinary glucuronidated and sulfated tea catechins after the administration of green tea to humans, mouse and rats [109]. The major conjugates were identified as monoglucuronides and monosulfates of EGC and EC. Besides these metabolites, also G-methyl-EGC-G-glucuronides, O-sulfates and O-methyl-EC-O-sulfates in human urine were detected. Furthermore, the ring-fission metabolites of EGC and (-)-epicatechin, 5-(3 ,4 ,5 -trihydroxyphenyl)-y-valerolactone and 5-(3 ,4 -dihydroxyphenyl)- valerolactone respectively, have been detected in the monoglucuronide and monosulfate forms. 

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