Sex Differences in the Metabolism of (+)- and (-)-Limonene Enantiomers to Carveol and Perillyl Alcohol Derivatives by Cytochrome P450 Enzymes in Rat Liver Microsomes
详细信息 查看全文
- 作者：Mitsuo Miyazawa ; Masaki Shindo ; and Tsutomu Shimada
- 刊名：Chemical Research in Toxicology
- 出版年：2002
- 出版时间：January 2002
- 年：2002
- 卷：15
- 期：1
- 页码：15 - 20
- 全文大小：78K
- 年卷期：v.15,no.1(January 2002)
- ISSN：1520-5010
文摘
(+)-Limonene is reported to cause nephropathy in male rats, but not in female rats andother species of animals including mice, rabbits, guinea pigs, and dogs. Male rats contain highlevels of 
2u-globulin in kidneys, and it has been shown that limonene and/or its metabolitesare able to bind noncovalently to 2u-globulin, resulting in an accumulation of protein dropletsin the renal tubules. In this study, we investigated whether (+)- and (-)-limonene enantiomersare differentially metabolized by liver microsomes of male and female rats. (+)- and(-)-limonene enantiomers were found to be oxidized to their respective trans-carveol (6-hydroxylation) and perillyl alcohol (7-hydroxylation) derivatives in greater amounts by livermicrosomes of male rats than those of female rats. The limonene hydroxylation activities werenot detected in liver microsomes of rat fetuses and were increased developmentally after birth,only in male rats. Treatment of male rats with phenobarbital significantly increased livermicrosomal 6-hydroxylation activities with both enantiomers whereas 
-naphthoflavone,isosafrole, and pregnenolone 16-carbonitrile did not cause such effects. Anti-P450 2C9 whichcross-reacts with rat P450 2C11 inhibited limonene hydroxylations catalyzed by livermicrosomes of untreated male rats, and it was also found that anti-P450 2B1 suppressed theactivities catalyzed by liver microsomes of phenobarbital-treated rats. Possible roles of P4502C11 and P450 2B1 in the limonene hydroxylation activities were supported by the experimentswith purified rat liver P450s in reconstitution systems and with recombinant rat P450s inTrichoplusia ni. Our present results showing that there are sex-related differences in theoxidative metabolism of limonene enantiomers by liver microsomes may provide usefulinformation on the basis of limonene-induced toxicities in different animal species.
2u-globulin in kidneys, and it has been shown that limonene and/or its metabolitesare able to bind noncovalently to 2u-globulin, resulting in an accumulation of protein dropletsin the renal tubules. In this study, we investigated whether (+)- and (-)-limonene enantiomersare differentially metabolized by liver microsomes of male and female rats. (+)- and(-)-limonene enantiomers were found to be oxidized to their respective trans-carveol (6-hydroxylation) and perillyl alcohol (7-hydroxylation) derivatives in greater amounts by livermicrosomes of male rats than those of female rats. The limonene hydroxylation activities werenot detected in liver microsomes of rat fetuses and were increased developmentally after birth,only in male rats. Treatment of male rats with phenobarbital significantly increased livermicrosomal 6-hydroxylation activities with both enantiomers whereas -naphthoflavone,isosafrole, and pregnenolone 16-carbonitrile did not cause such effects. Anti-P450 2C9 whichcross-reacts with rat P450 2C11 inhibited limonene hydroxylations catalyzed by livermicrosomes of untreated male rats, and it was also found that anti-P450 2B1 suppressed theactivities catalyzed by liver microsomes of phenobarbital-treated rats. Possible roles of P4502C11 and P450 2B1 in the limonene hydroxylation activities were supported by the experimentswith purified rat liver P450s in reconstitution systems and with recombinant rat P450s inTrichoplusia ni. Our present results showing that there are sex-related differences in theoxidative metabolism of limonene enantiomers by liver microsomes may provide usefulinformation on the basis of limonene-induced toxicities in different animal species.