Identification of inhibitory component in cinnamon--O-methoxycinnamaldehyde inhibits CYP1A2 and CYP2E1-.
The Cinnamomi Cortex and Ephedra Herba were found to more strongly inhibit aminopyrine N-demethylation in rat liver microsomes compared to other constituents included in Sho-seiryu-to. The component inhibiting drug oxidations catalyzed by CYP1A2 and CYP2E1 was isolated from Cinnamomi Cortex, and was identified as o-methoxycinnamaldehyde (OMCA). When phenacetin and 4-nitrophenol were used as probe substrates for CYP1A2 and CYP2E1, respectively, the OMCA was shown to be a competitive inhibitor against CYP1A2 while it was a mixed type inhibitor against CYP2E1. The inhibitory effect of OMCA on 4-nitrophenol 2-hydroxylation (K(i)=6.3 microM) was somewhat potent compared to that observed on phenacetin O-deethylation (K(i)=13.7 microM) in rat liver microsomes.
Hasegawa
Atsushi
A
Division of Pharmacy, Chiba University Hospital, Faculty of Medicine, Chiba University, Japan. a-hasegawa@umin.ac.jp
Yoshino
Masaki
M
Nakamura
Hiroyoshi
H
Ishii
Itsuko
I
Watanabe
Toshiko
T
Kiuchi
Masahiro
M
Ishikawa
Tsutomu
T
Ohmori
Shigeru
S
Kitada
Mitsukazu
M