David G. Ahern

Arachidonoyl ethanolamide-[1,2-14C] as a substrate for anandamide amidase

Arachidonoyl ethanolamide-[1,2-14C] was prepared and evaluated as a substrate for anandamide amidase in a radioenzymatic assay that does not require a thin layer chromatography separation step. Using this substrate the release of ethanolamine-[1,2-14C] is linear for approximately thirty minutes. Anandamide amidase exhibits maximal activity between pH 8 and pH 9 with a steep decline in activity at pH values below 6 and above 10. Arachidonoyl ethanolamide-[1,2-14C] was used for the assay of anandamide amidase from 10 micrograms to 100 micrograms protein, from cow brain homogenate, in a 0.2 ml incubation mixture. When plotted as a rectangular hyperbola of the steady-state Michaelis-Menten equation, an approximate Km of 30 +/- 7 microM and a Vmax of 198 +/- 13 nmoles ethanolamine formed per hour per mg protein homogenate was obtained.

Aporphines. 58. N-(2-chloroethyl) [8,9-2H]norapomorphine, an irreversible ligand for dopamine receptors: synthesis and application.

The synthesis of the title compounds (1c and its 2H isomer 1b) from N-(2-hydroxyethyl)norapomorphine was carried out by ring bromination, followed by chlorination to the 2-chloroethyl compound 6. Further reduction with 2H2 or 3H2 and Pd/C gave 1b or 1c. Radiochemically pure (97%) 1c was obtained with a specific activity of 16.3 Ci/mmol. The purity of 1c was determined by LC, HPLC, UV, and NMR. [3H]NCA was shown to label the D2 receptor; however, the D2 signal appears to be only a small portion of the total signal, which may include binding to other dopamine receptor subtypes (D1 and D3).