Synthesis and intramitochondrial levels of valproyl-coenzyme A metabolites

A number of valproate adverse reactions are due to its interference with se veral metabolic pathways, including that of fatty acid oxidation. In order to resolve which mitochondrial enzymes of fatty acid oxidation are inhibite d by which VPA intermediates we have developed methods to synthesize their CoA ester forms. This paper describes the synthesis of VPA acyl-CoA ester m etabolites as well as data on the fate of VPA in rat Liver mitochondria, Va lproyl-CoA, Delta (2)-valproyl-CoA, and 3-OH-valproyl-CoA were obtained thr ough chemical synthesis. 3-Keto-valproyl-CoA was prepared by a novel enzyma tic procedure followed by a combination of solid-phase extraction and prepa rative HPLC purification. This approach proved to be efficient in obtaining all the beta -oxidation intermediates of valproyl-CoA The synthetic standa rds were used for the determination of intramitochondrial concentrations of valproyl-CoA, Delta (2)-valproyl-CoA, 3-OH-valproyl-CoA, and 3-keto-valpro yl-CoA by HPLC. These levels were determined after incubation of intact rat Liver mitochondria with VPA under conditions of state 3 and state 4 respir ation, The results show that valproyl-CoA and to a much lesser extent 3-ket o-valproyl-CoA are the main metabolites of VPA in mitochondria, This inform ation will be of great use in resolving the mechanisms involved in the inhi bition of mitochondrial processes hire fatty acid oxidation by VPA. (C) 200 1 Academic Press.