Design, Synthesis, and Evaluation of 2-Diethanolamino-4,8-diheptamethyleneimino-2-(<i>N</i>-aminoethyl-<i>N</i>-ethanolamino)-6-(<i>N,N</i>-diethanolamino)pyrimido[5,4-<i>d</i>]pyrimidine-fluorescein Conjugate (8MDP-fluor), As a Novel Equilibrative Nucleoside Transporter Probe
作者:Wenwei Lin、John K. Buolamwini
DOI:10.1021/bc2000758
日期:2011.6.15
Nucleoside transporters are integral membrane glycoproteins that play critical roles in physiological nucleoside and nucleobase fluxes, and influence the efficacy of many nucleoside chemotherapy drugs. Fluorescent reporter ligands/substrates have been shown to be useful in the analysis of nucleoside transporter (NT) protein expression and discovery of new NT inhibitors. In this study, we have developed a novel dipyridamole (DP)-based equilibrative nucleoside transporter 1 (ENT1) fluorescent probe. The potent ENT1 and ENT2 inhibitor analogue of dipyridamole, 2,6-bis(diethanolamino)-4,8-diheptamethyleneiminopyrimido[5,4-d]pyrimidine (4, 8MDP), was modified to replace one beta-hydroxyethyl group of the amino substituent at the 2-position with a beta-aminoethyl group and then conjugated through the amino group to 6-(fluorescein-5carboxamido)hexanoyl moiety to obtain a new fluorescent molecule, 2-diethanolamino-4,8-diheptamethyleneimino-2-(N-aminoethyl-N-ethanolamino)-6-(N,N-diethanolamino)pyrimido[5,4-d]pyrimidine-fluorescein conjugate, designated 8MDP-fluorescein (8MDP-fluor, 6). The binding affinities of 8MDP-fluor at ENT1 and ENT2 are reflected by the uridine uptake inhibitory K(i) values of 52.1 nM and 285 nM, respectively. 8MDP-fluor was successfully demonstrated to be a flow cytometric probe for ENT1 comparable to the nitrobenzylmercaptopurine riboside (NBMPR) analogue ENT1 fluorescent probe SAENTA-X8-fluorescein (SAENTA-fluor, 1). This is the first reported dipyridamole-based ENT1 fluorescent probe, which adds a novel tool for probing ENT1, and possibly ENT2.