In:
Zeitschrift für Naturforschung C, Walter de Gruyter GmbH, Vol. 53, No. 3-4 ( 1998-4-1), p. 173-181
Abstract:
The inhibitory effect of a series of 5′-O-amino acid and oligopeptide derivatives of uridine on rat liver UDP-glucuronosyltransferase (UGT) activities was investigated using two assay systems. A quantitative structure-activity relationship (QSAR) study was performed. The compounds include a lipophilic residue linked to the nucleoside by a variable spacer. More over, half of the derivatives have two spacers linked to the uridine moiety. Compound 1, a serine derivative of isopropylideneuridine, was found to be the most potent inhibitor of both 4-nitrophenol (4-NP) and phenolphthalein (PPh) glucuronidation, with an I 50 of 0.45 mᴍ and 0.22 mᴍ , respectively. Kinetic studies with this substance revealed a mixed type of inhibition towards 4-NP and UDP-glucuronic acid, with apparent Ki values of 150 μᴍ and 120 μᴍ , respectively. The dipeptide derivatives 11-14 exhibited a low activity against 4-NP conjuga tion. However, a marked suppression of PPh glucuronidation was found with compounds 11 and 13. Generally, compounds with two spacers are more inhibitory against the UGT activities studied. The QSAR analysis outlined the significance of the spacers with a minimum length of 5 atoms and lipophilic residues linked to them for the inhibitory effect of the compounds. The most significant contribution to this effect is given by the six-atom spacer for both, 4-NP and PPh substrates. 4-NP converting UGT isoforms seem to respond more specifically to the inhibitors: a five-atom for the first and a six-atom for the second spacer enhance binding to both 4-NP and PPh conjugating isoenzymes, while a long second spacer contributes to inhibitor binding to UGT isoforms only converting PPh.
Type of Medium:
Online Resource
ISSN:
1865-7125
,
0939-5075
DOI:
10.1515/znc-1998-3-406
Language:
English
Publisher:
Walter de Gruyter GmbH
Publication Date:
1998
detail.hit.zdb_id:
2078107-6
SSG:
12
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