Preferential overexpression of a class MU glutathione S-transferase subunit in mouse liver by myristicin.

The present studies were undertaken to elucidate the mechanism of induction of glutathione S-transferase (GST) in mouse liver by myristicin, an active constituent of parsley leaf. A/J albino mice, given 5 to 50 mg doses of myristicin, showed 4- to 14-fold increase in liver GST specific activity over the control. GST purified from equal amounts of control and myristicin-treated livers indicated a marked increase in the GST activity. A relatively higher increase in GST activity towards 2,4-dichloronitrobenzene and a profound increase in the levels of GST mu on Western blot analysis of the myristicin-treated mouse liver suggest a preferential induction of GST mu. Results of the study also indicate that out of the two mu class GST subunits (Mr. 26,500 and Mr. 25,000) expressed in liver only one (Mr. 26,500) is significantly elevated. Myristicin treatment caused a slight change in the GST pi levels while the levels of GST alpha showed a modest increase. These results suggest that myristicin could be an effective chemopreventive agent, particularly for carcinogens that are detoxified by the mu class GST.