Synthesis of (2-[11C]methoxy)rotenone, a marker of mitochondrial complex I activity

Recent studies suggest that defects in the function of the complexes of the electron transport chain might be involved in the pathology of neurological diseases such as mitochondrial encephalopathies, Parkinson's, Huntington's and Alzheimer's disease. Rotenone is a potent reversible competitive inhibitor of complex I (NADH-CoQ reductase). To study the possible involvement of complex I in such diseases, we synthesized (2-[11C]methoxy)rotenone by [11C]alkylation of 2-O-desmethyl rotenone methyl enol ether followed by hydrolysis of the enol ether to the ketone using aqueous trifluoroacetic acid. (2-[11C]Methoxy)rotenone was purified by high pressure liquid chromatography (silica gel) and was obtained in 7-10% yields decay corrected to end of bombardment in synthesis times typically shorter than 48 min. Radiochemical purities were over 95% and specific activities averaged 1000 Ci/mmol at end of synthesis.