Identification of New Flavone-8-Acetic Acid Metabolites Using Mouse Microsomes and Comparison with Human Microsomes

Abstract

ABSTRACT:Flavone-8-acetic acid (FAA) is a potent anticancer agent in mouse but has not shown activity in humans. Because FAA metabolism could play a role in this interspecies difference, our aim was to identify the metabolites formed in vitro using mouse microsomes compared with those in human microsomes. Mouse microsomes produced six metabolites as detected by reversed-phase highperformance liquid chromatography-mass spectrometry (MS). Three metabolites were identified as the 3-, 4-, or 6-hydroxy-FAA, by comparison with retention times and UV and MS spectra of standards. Two metabolites presented a molecular weight of 296 (FAA ‫؍‬ 280) indicating the presence of one oxygen but did not correspond to any monohydroxylated FAA derivative. These two metabolites were identified as epoxides because they were sensitive to epoxide hydrolase. The position of the oxygen was determined by the formation of the corresponding phenols under soft acidic conditions: one epoxide yielded the 3-and 4-hydroxy-FAA, thus corresponding to the 3,4-epoxy-FAA, whereas the other epoxide yielded 5-and 6-hydroxy-FAA, thus identifying the 5,6-epoxy-FAA. The last metabolite was assigned to the 3,4-dihydrodiol-FAA because of its molecular weight (314) and sulfuric acid dehydration that indicated that the 3-and 4-positions were involved. Compared with mouse microsomes, human microsomes (2 pools and 15 individual microsomes) were unable to metabolize FAA to a significant extent. In conclusion, we have identified six new FAA metabolites formed by mouse microsomes, whereas human microsomes could not metabolize this flavonoid to a significant extent. The biological importance of the new metabolites identified herein remains to be evaluated.

Characterization of monohydroxylated derivatives of the anticancer agent flavone‐8‐acetic acid by liquid chromatography with on‐line UV and mass spectrometry

“…Flavone‐8‐acetic acid (FAA) and its monohydroxylated derivatives at positions 3, 5, 7, 2′, 3′ or 4′ were kindly provided by Dr Jean‐Jacques Berthelon (Merck‐Lipha Santé, Lyon, France). The 6‐OH‐FAA was synthesized according to our previously described methodology using appropriate starting materials 13–16. Standard solutions at 5 µg/mL of each derivative were prepared in methanol.…”

“…As part of an ongoing project on FAA metabolism, we have previously shown that FAA can be metabolized in vitro into several monohydroxylated metabolites using mouse microsomes 13. The challenge of FAA metabolite identification led us to consider every possible position where a hydroxyl group could be found on the parent compound after phase 1 metabolism by cytochrome P450s, for example.…”

Drug design: hiding in full view

“…Other phenylated drugs can be metabolized to an epoxy derivative, which is then opened by epoxide hydrolase to form a catechol ring, which then is oxidized to an oquinone. In the case of flavone-8-acetic acid, the resultant catechol derivative [Pham et al, 2007] can be expected to form an o-quinone in which the double bonds are conjugated with the adjacent flavone pyrone group. This additional allylic ketone group should enhance the activity.…”

<p>Metabolite Profiling in Anticancer Drug Development: A Systematic Review</p>

“…Out of 78 articles included in the analysis (42 in vitro, 42 in vivo, and 16 clinical studies), 47 (60.3%), 14 (17.9%) and 17 (21.8%) articles respectively, investigated metabolite profiles of conventional anticancer drugs/synthetic anticancer candidates, small-molecules targeted therapy, and herbderived compounds with anticancer activities. These studies involved a total of 57 (57.0%) conventional anticancer drugs/ synthetic anticancer candidates, 6, 22 (22.0%) studies for small-molecules targeted therapy, 4,5,[59][60][61][62][63][64][65][66][67][68][69][70] and 21 (21.0%) studies for herb-derived compounds with anticancer activities 2,3,7,9,[71][72][73][74][75][76][77][78][79][80][81][82][83] (Tables 1-3). Anticancer drugs or candidate compounds are metabolized by either Phase I, or phase II metabolizing enzyme alone, or both phase I and phase II metabolizing enzymes.…”