PT  - JOURNAL ARTICLE
AU  - Geri A. Sawada
AU  - Lawrence R. Williams
AU  - Barry S. Lutzke
AU  - Thomas J. Raub
TI  - Novel, Highly Lipophilic Antioxidants Readily Diffuse Across the Blood-Brain Barrier and Access Intracellular Sites
DP  - 1999 Mar 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 1327--1333
VI  - 288
IP  - 3
4099  - http://jpet.aspetjournals.org/content/288/3/1327.short
4100  - http://jpet.aspetjournals.org/content/288/3/1327.full
SO  - J Pharmacol Exp Ther1999 Mar 01; 288
AB  - In an accompanying article, an in vitro assay for permeability predicts that membrane-protective, antioxidant 2,4-diamino-pyrrolo[2,3-d]pyrimidines should have improved blood-brain barrier (BBB) permeation over previously described lipophilic antioxidants. Using a first-pass extraction method and brain/plasma quantification, we show here that two of the pyrrolopyrimidines, one of which is markedly less permeable, readily partition into rat brain. The efficiency of extraction was dependent on serum protein binding, and in situ efflux confirms the in vitro data showing that PNU-87663 is retained in brain longer than PNU-89843. By exploiting inherent fluorescence properties of PNU-87663, its distribution within brain and within cells in culture was demonstrated using confocal scanning laser microscopy. PNU-87663 rapidly partitioned into the cell membrane and equilibrates with cytoplasmic compartments via passive diffusion. Although partitioning of PNU-87663 favors intracytoplasmic lipid storage droplets, the compound was readily exchangeable as shown by efflux of compound from cells to buffer when protein was present. The results demonstrated that pyrrolopyrimidines were well suited for quickly accessing target cells within the central nervous system as well as in other target tissues. The American Society for Pharmacology and Experimental Therapeutics