Characterization of in vitro metabolites from human liver microsomes using directly coupled hplc-nmr: application to a phenoxathiin monoamine oxidase-A inhibitor.

1. The metabolism of 1-ethylphenoxathiin-10,10-dioxide (BW1370U87), an experimental compound designed as an inhibitor of monoamine oxidase-A for use as a possible anti-depression agent, has been studied in a human liver microsome preparation. 2. The identities of the metabolites have been determined using directly coupled hplc-1H nmr at 600 MHz in the stop-flow mode in this first study of in vitro xenobiotic metabolism using hplc-nmr. 3. The xenobiotic substances that were identified comprised the parent compound BW1370U87 (with -CH2CH3 at C1) together with sidechain-oxidized metabolites with C1 substituents of -CHOH.CH3, -CH2.CH2OH, -CHOH.CH2OH and -CH2.COOH, plus the unsubstituted phenoxathiin-10,10-dioxide.