Effects Of Poria Cocos On Activity And MRNA Expression Of Cytochrome P450 Enzymes In Rats

Objective: Poria cocos,a kind of edible and pharmaceutical mushroom that has a long history of medicinal use in Asian countries,has been used for many years for its unique therapeutic effects.Poria cocos is commercially available and is popularly used in medicines,food and health care products.Recently,herbal medicines are frequently used worldwide,taking herbs together with prescribed western medication places patients at a potential risk for herb–drug interactions(HDIs).The Cytochrome P450(CYP450)superfamily,one of the most important drug-metabolizing enzyme systems in humans,is responsible for the oxidative metabolism of numerous xenobiotic substances as well as endogenous substrates.However,no systematic study has been reported emphasizing the impact of Poria cocos on CYP450 and potential interactions are not predictable when it is co-administered with other drugs.The purpose of this study was to investigate the influences of Poria cocos on the activities and m RNA expression of rat Cyp450 enzymes.Methods: Firstly,this study developed corresponding methods to determine the main ingredients in the water-soluble extracts and ethanol-soluble extracts.Secondly,an LC-MS/MS was used for the determination of probe substrates for Cyp1a2,Cyp2b1,Cyp2c6,Cyp2c11,Cyp2e1 and Cyp3a1 in rat plasma.Thirdly,48 male rats were randomly divided into seven groups(n=6): blank control group,low,medium,high dosage group of aqueous extract of Poria cocos(1,2,4g/kg);low,medium,high dosage group of ethanol extract of Poria cocos(1,2,4g/kg).Then,the aqueous and ethanol extract were oral administration for consective 14 days while control group received physiological saline for 14 days to rats.At the last day,a cocktail solution,which contained phenacetin(1mg/kg),bupropion(1mg/kg),diclofenac sodium(1mg/kg),omeprazole(1mg/kg),chlorzoxazone(1mg/kg)and midazolam(1 mg/kg),was administered by tail vein injection to all rats.Blood samples were collected at a series of time-points and the concentrations of the probe drugs were quantified using LC-MS/MS.The corresponding pharmacokinetic parameters were calculated by thesoftware of DAS 2.0.Lastly 48 male rats were randomly divided into seven groups which is the same to the study of activities of rat Cyp450 enzymes.After the oral administration of extracts of Poria cocos for consective 14 days while control group received physiological saline in rats,at the last day,rats were executed and PCR technology was used to determine the m RNA expression of rat Cyp450 enzymes in rat liver.Results: The content of total polysaccharides were 0.2g/m L in 50 m L extractum in the aqueous extract from 500.0 grams of Poria cocos while the content of total triterpenes were 95.3% in 2.02 grams powder in the ethanol extract from 500.0 grams of Poria cocos,and the four main triterpenes referring to dehydrotumulosic acid,dehydropachymic acid,pachymic acid,dehydrotrametenolic acid were 9.60%,4.80%,12.40%,0.41% in the powder of ethanol extract,respectively.An LC-MS/MS was established for the determination of phenacetin,bupropion,diclofenac sodium,omeprazole,chlorzoxazone and midazolam in rat plasma and the method was formally validated.The study of activities of Cyp450 enzymes and m RNA expression in rats showed that the aqueous and ethanol extract of Poria cocos could significantly induce Cyp2b1,Cyp2c6,Cyp3a1 enzyme activity and m RNA expression.The aqueous of Poria cocos significantly induced Cyp1a2 enzyme activity,m RNA expression,but ethanol extract had no significant effect on Cyp1a2 enzyme activity and m RNA expression;Aqueous extract of Poria cocos had no significant effect on Cyp1a2 enzyme activity,m RNA expression while the ethanol extract of Poria cocos significantly induced Cyp2e1 enzyme activity,m RNA expression;The aqueous and ethanol extract of Poria cocos had no significant effect on Cyp2c11 m RNA expression and enzyme activity levels.Conclusion: Poria cocos had selective regulations on different P450 subtypes in rats which is linked to different constitudes and doses.Except for Cyp2c11,Poria cocos had inductive effects on Cyp1a2,Cyp2b1,Cyp2c6,Cyp2e1 and Cyp3a1 at different degree.It suggested that full consideration shall be given to its side effects caused by HDIs when they are administrated with other drugs,particularly in the combinationwith Cyp1a2,Cyp2b1,Cyp2c6,Cyp2e1 and Cyp3a1 metabolism-related drugs in clinical practice and in live.Meanwhile,whether the induction effect of rat Cyp P450 enzymes gets involved in compatibility mechanism of Poria cocos deserves further studies.