Blood-Brain-Barrier-Penetrating 6-Halogenopurines Suitable as Pro-Probes for Positron Emission Tomography are Substrates for Human Glutathione Transferases
Birgitta Sjodin and Bengt Mannervik*
Department of Neurochemistry, Stockholm University, Arrhenius Laboratories, SE-10691 Stockholm, Sweden
- *Corresponding Author:
- Bengt Mannervik
Department of Neurochemistry
Svante Arrhenius väg 16B, SE-10691 Stockholm, Sweden
E-mail: [email protected]
Received date: February 29, 2016; Accepted date: April 12, 2016; Published date: April 15, 2016
Citation: Sjodin B, Mannervik B (2016) Blood-Brain-Barrier-Penetrating 6-Halogenopurines Suitable as Pro-Probes for Positron Emission Tomography are Substrates for Human Glutathione Transferases. J Pharma Reports 1:114. doi:10.4172/jpr.1000114
Copyright: © 2016 Mannervik B, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
6-Chloro- and 6-bromopurines can cross the blood-brain barrier and in situ give rise to substrates of multidrug resistance-associated proteins (MRPs). The electrophilic purines form glutathione conjugates in reactions catalyzed by intracellular glutathione transferases (GSTs), and the conjugates are subsequently exported from the cells by ATPdependent membrane transporters. In rodent model systems it has been demonstrated that suitably radiolabeled 6-halogenopurines by this scheme are pro-probes useful in monitoring the functionality of MRPs in intact brains using positron emission tomography. Prior to applications in human subjects it is imperative to establish the purine pro-probes as effective substrates for human GSTs occurring in brain and other tissues. We have developed a spectrophotometric assay for the glutathione conjugation and determined specific activities with a range of human GSTs as well as with some rat GSTs for comparison. The ubiquitous GST P1-1 showed the highest activities with the 6-halogenopurines, which bodes well for the application of pro-probes for human investigations.