TY - JOUR
T1 - Valproyl-dephosphoCoA: a novel metabolite of valproate formed in vitro in rat liver mitochondria
AU - Silva, Margarida F. B.
AU - Ijlst, Lodewijk
AU - Allers, Paul
AU - Jakobs, Cornelis
AU - Duran, Marinus
AU - de Almeida, Isabel Tavares
AU - Wanders, Ronald J. A.
PY - 2004
Y1 - 2004
N2 - The mitochondrial metabolism of valproic acid (VPA) was investigated in vitro to elucidate its beta-oxidation pathway since the characterization of VPA intermediates in the acyl-CoA thioester form, and not just in their free acid form, has not been fully achieved. Intact rat liver mitochondria were incubated with [4,5-3H2]VPA and [2-3H]VPA. The respective intermediates, valproyl-CoA, Delta2(E)-valproyl-CoA, 3-hydroxyvalproyl-CoA, and 3-oxovalproyl-CoA were analyzed by reverse phase high performance liquid chromatography (HPLC) with radioisotope and UV detection. An unknown metabolite, originating from both labeled substrates, was detected. It was identified as valproyl-dephosphoCoA (valproyl-dephCoA) by fast atom bombardment mass spectrometry (FAB-MS) analysis of the corresponding HPLC peak fraction. The FAB-MS spectrum of the authentic chemically synthesized valproyl-dephCoA proved to be consistent with that of the unknown compound. Valproyl-dephCoA is produced from valproyl-CoA in mitochondria, probably via a phosphatase-catalyzed reaction. This conversion was shown to be more dependent on the energy state involving [AXP] ([AXP] = [ATP] + [ADP] + [AMP]) and [phosphate] concentrations rather than the strict mitochondrial [ATP]/[ADP] ratio. The results indicate that higher concentrations of AXP and phosphate inhibit the dephosphorylation of valproyl-CoA. A complete understanding of the toxic significance of valproyl-dephCoA formation in vivo as a potential inhibitor of fatty acid beta-oxidation is important to clarify the pathogenesis of VPA-associated hepatotoxicity
AB - The mitochondrial metabolism of valproic acid (VPA) was investigated in vitro to elucidate its beta-oxidation pathway since the characterization of VPA intermediates in the acyl-CoA thioester form, and not just in their free acid form, has not been fully achieved. Intact rat liver mitochondria were incubated with [4,5-3H2]VPA and [2-3H]VPA. The respective intermediates, valproyl-CoA, Delta2(E)-valproyl-CoA, 3-hydroxyvalproyl-CoA, and 3-oxovalproyl-CoA were analyzed by reverse phase high performance liquid chromatography (HPLC) with radioisotope and UV detection. An unknown metabolite, originating from both labeled substrates, was detected. It was identified as valproyl-dephosphoCoA (valproyl-dephCoA) by fast atom bombardment mass spectrometry (FAB-MS) analysis of the corresponding HPLC peak fraction. The FAB-MS spectrum of the authentic chemically synthesized valproyl-dephCoA proved to be consistent with that of the unknown compound. Valproyl-dephCoA is produced from valproyl-CoA in mitochondria, probably via a phosphatase-catalyzed reaction. This conversion was shown to be more dependent on the energy state involving [AXP] ([AXP] = [ATP] + [ADP] + [AMP]) and [phosphate] concentrations rather than the strict mitochondrial [ATP]/[ADP] ratio. The results indicate that higher concentrations of AXP and phosphate inhibit the dephosphorylation of valproyl-CoA. A complete understanding of the toxic significance of valproyl-dephCoA formation in vivo as a potential inhibitor of fatty acid beta-oxidation is important to clarify the pathogenesis of VPA-associated hepatotoxicity
U2 - https://doi.org/10.1124/dmd...
DO - https://doi.org/10.1124/dmd...
M3 - Article
C2 - 15483197
SN - 0090-9556
VL - 32
SP - 1304
EP - 1310
JO - Drug metabolism and disposition: the biological fate of chemicals
JF - Drug metabolism and disposition: the biological fate of chemicals
IS - 11
ER -