2′-, 3′-, and 4′-Methoxyflavones (MeFs) were incubated with nine forms of recombinant human cytochrome P450 (P450 or CYP) enzymes in the presence of an NADPH-generating system and the products formed were analyzed with LC-MS/MS methods.

CYP1B1.1 and 1B1.3 were highly active in demethylating 4′MeF to form 4′-hydroxyflavone (rate of 5.0 nmol/min/nmol P450) and further to 3′,4′-dihydroxyflavone (rates of 2.1 and 0.66 nmol/min/nmol P450, respectively). 3′MeF was found to be oxidized by P450s to m/z 239 (M-14) products (presumably 3′-hydroxyflavone) and then to 3′,4′-dihydroxyflavone. P450s also catalyzed oxidation of 2′MeF to m/z 239 (M-14) and m/z 255 (M-14, M-14 + 16) products, presumably mono- and di-hydroxylated products, respectively.

At least two types of ring oxidation products having m/z 269 fragments were formed, although at slower rates than the formation of mono- and di-hydroxylated products, on incubation of these MeFs with P450s; one type was products oxidized at the C-ring, having m/z 121 fragments, and the other one was the products oxidized at the A-ring (having m/z 137 fragments).

Molecular docking analysis indicated the preference of interaction of O-methoxy moiety of methoxyflavones in the active site of CYP1A2.

These results suggest that 2′-, 3′-, and 4′-methoxyflavones are principally demethylated by human P450s to form mono- and di-hydroxyflavones and that direct oxidation occurs in these MeFs to form mono-hydroxylated products, oxidized at the A- or B-ring of MeF.

在产生NADPH的系统中，将2'-，3'-和4'-甲氧基黄酮（MeFs）与9种形式的重组人细胞色素P450（P450或CYP）酶一起孵育，并用LC- MS / MS方法。

CYP1B1.1和1B1.3在4'MeF脱甲基形成4'-羟基黄酮（5.0 nmol / min / nmol P450的速率）和进一步形成3'，4'-二羟基黄酮（2.1和0.66 nmol / min / nmol P450）。发现3'MeF被P450氧化为m / z 239（M-14）产物（大概是3'-羟基黄酮），然后被氧化为3'，4'-二羟基黄酮。P450还将2'MeF催化氧化为m / z 239（M-14）和m / z 255（M-14，M-14 + 16）产品，可能分别是单羟基和二羟基产品。

将这些MeF与P450一起孵育时，至少形成了两种类型的具有m / z 269片段的环氧化产物，尽管其速度比单羟基和二羟基化产物的形成慢。一种是在C环上氧化的产物，具有m / z 121片段，另一种是在A环上氧化的产物（具有m / z 137片段）。

分子对接分析表明在CYP1A2的活性位点中，甲氧基黄酮的O-甲氧基部分相互作用的偏好。

这些结果表明2'-，3'-和4'-甲氧基黄酮主要被人P450脱甲基形成单羟基和二羟基黄酮，并且在这些MeF中发生直接氧化形成单羟基化产物，在A处被氧化。 -或MeF的B环。