The metabolism of the alkylphosphate antagonists and its pharmacologic implications

Cyanogenic glucosides: the biosynthetic pathway and the enzyme system involved

In vitro studies with a microsomal system obtained from etiolated sorghum seedlings have indicated a biosynthetic pathway for cyanogenic glucosides involving amino acids, N-hydroxyamino acids, aldoximes, nitriles and cyanohydrins. NADPH is an essential cofactor. Simultaneous measurements of tyrosine metabolism and oxygen consumption show that three molecules of oxygen are consumed for each molecule of p-hydroxymandelonitrile produced. This indicates the operation of three monooxygenases in the pathway and implies the involvement of one hitherto undetected intermediate in the pathway. The nature of this intermediate is unknown. Gel filtration and sucrose gradient centrifugation of the microsomal system resulted in a more than tenfold increase in specific activity. Attempts to further purify the system did not produce preparations of higher specific activity because of a simultaneous partial loss of essential components as demonstrated by reconstitution experiments.

Identification of two metabolites of the cholinesterase reactivator HI-6 isolated from rat urine

Two metabolites, isolated from the urine of rats given the cholinesterase reactivator HI-6 intravenously, still contained quaternary nitrogen atoms and therefore could not be extracted from aqueous solutions by organic solvents. Both metabolites were isolated by preparative high performance liquid chromatography and were identified using mass spectrometry, gas chromatography, infrared spectrometry, ultraviolet spectrometry and proton nuclear magnetic resonance spectrometry. The structures were confirmed by in-vitro preparation of the compounds. both metabolites contained 2-pyridone moieties. One had an intact pyridinium-aldoxime moiety, and therefore could still be therapeutically active. The excretion of unchanged HI-6 together with the two identified metabolites does not provide for a 100% mass balance, indicating that in the rat, other, as yet unidentified, metabolites must be formed.