TY - JOUR
T1 - Direct observation of a fluorinated anticonvulsant in brain tissue using 19F-NMR techniques
AU - Canney, Daniel J.
AU - Covey, Douglas F.
AU - Evers, Alex S.
N1 - Funding Information:
Acknowledgements-The authors wish to thank Dr. Katherine Holland and Ann McKeon for assistancew ith the animalt estinga nd radioligandb indinga ssaysW. e also wisht o thankD r. Andre d’Avignon for helpfuld iscussions. This work was supportedb y grants from the Lucille P. Markey Charitable Trust to Washington University (D.F.C.), and NIH grantsG M-37846( A.S.E.), NS14834 (D.F.C.) and5 -T32-NSO712(D9 .J.C.). Assistancew asa lso providedb y the WashingtonU niversity High Resolution NMR (NIH 1 SlO RR00204a nd the Monsanto Co.) and Mass Spectrometry(N IH RRO0954)F acilities.
PY - 1993/2/24
Y1 - 1993/2/24
N2 - A fluorinated derivative of an anticonvulsant γ-butyrolactone [α-(1,1-difluoroethyl)-α-methyl-γ-butyrolactone; γ-DFGBL] was synthesized as a probe for NMR spectroscopic observation of the drug in brain tissue. The fluorinated compound is an efficacious anticonvulsant in mice, and inhibits the specific binding of [35S]t-butylbicyclophosphorothionate ([35SITBPS) to mouse brain membranes with a concentration dependence similar to that of the non-fluorinated compound α-ethyl-α-methyl-γ-butyrolactone. Quantitative 19F-NMR spectroscopic studies, coupled with Chromatographic measurements of drug tissue concentration, showed that virtually all of the α-DFGBL in brain was NMR-observable and that, following intraperitoneal injection, α-DFGBL rapidly achieved millimolar concentrations in brain. The 19F-NMR spectra of a α-DFGBL in brain and liver tissue were broad (1-2 ppm) and complex, exhibiting multiple chemical shift features. The major chemical shift features in these spectra were assigned on the basis of differential extraction and comparison of 19F spin-spin relaxation times (T2s) and 19F chemical shifts of α-DFGBL in tissue to those in pure solvents. The major feature at 10.4 ppm in the tissue spectra was assigned to a weakly polar, membrane-associated environment for the fluorinated compound, while the feature at 11.2 ppm was assigned to an aqueous environment for α-DFGBL. The drug was in slow exchange between these two environments in brain. In addition, the feature at lowest field (9.7-9.8 ppm) was identified as a water-soluble hydroxy-acid metabolite of α-DFGBL produced by the liver. These data indicate that γ-butyrolactone anticonvulsants achieve high concentrations in brain, where they exist in several, largely membrane-associated, environments. These findings are consistent with the purported action of the γ-butyrolactones as low-affinity modulators of γ-aminobutyric acid-A channels.
AB - A fluorinated derivative of an anticonvulsant γ-butyrolactone [α-(1,1-difluoroethyl)-α-methyl-γ-butyrolactone; γ-DFGBL] was synthesized as a probe for NMR spectroscopic observation of the drug in brain tissue. The fluorinated compound is an efficacious anticonvulsant in mice, and inhibits the specific binding of [35S]t-butylbicyclophosphorothionate ([35SITBPS) to mouse brain membranes with a concentration dependence similar to that of the non-fluorinated compound α-ethyl-α-methyl-γ-butyrolactone. Quantitative 19F-NMR spectroscopic studies, coupled with Chromatographic measurements of drug tissue concentration, showed that virtually all of the α-DFGBL in brain was NMR-observable and that, following intraperitoneal injection, α-DFGBL rapidly achieved millimolar concentrations in brain. The 19F-NMR spectra of a α-DFGBL in brain and liver tissue were broad (1-2 ppm) and complex, exhibiting multiple chemical shift features. The major chemical shift features in these spectra were assigned on the basis of differential extraction and comparison of 19F spin-spin relaxation times (T2s) and 19F chemical shifts of α-DFGBL in tissue to those in pure solvents. The major feature at 10.4 ppm in the tissue spectra was assigned to a weakly polar, membrane-associated environment for the fluorinated compound, while the feature at 11.2 ppm was assigned to an aqueous environment for α-DFGBL. The drug was in slow exchange between these two environments in brain. In addition, the feature at lowest field (9.7-9.8 ppm) was identified as a water-soluble hydroxy-acid metabolite of α-DFGBL produced by the liver. These data indicate that γ-butyrolactone anticonvulsants achieve high concentrations in brain, where they exist in several, largely membrane-associated, environments. These findings are consistent with the purported action of the γ-butyrolactones as low-affinity modulators of γ-aminobutyric acid-A channels.
UR - http://www.scopus.com/inward/record.url?scp=0027463186&partnerID=8YFLogxK
U2 - 10.1016/0006-2952(93)90181-U
DO - 10.1016/0006-2952(93)90181-U
M3 - Article
C2 - 8452571
AN - SCOPUS:0027463186
SN - 0006-2952
VL - 45
SP - 949
EP - 959
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 4
ER -