ABSTRACT
Objective To characterize the metabolic kinetics of aloe emodin in human liver microsomes(HLM)and rat liver microsomes(RLM)and identify the CYP phenotyping of phaseⅠmetabolism. Methods Aloe emodin was incubated at 37℃ with HLM and RLM in the presence or absence of NADPH,UDGPA or NADPH+UDGPA. The remaining aloe emodin was determined with a validated LC-MS/MS method to assess the metabolic stability and enzymatic kinetics. A panel of rCYP isoforms(CYP1A2,2B6,2C8, 2C9,2C19,2D6 and 3A4)and HLM with specific inhibitors of CYP isoforms were used to identify the CYP phenotyping of aloe emo?din. Results In HLM and RLM,aloe emodin was metabolically eliminated in the presence of NADPH,with 85.8%and 81.7%of the parent compounds eliminated in 30 min,respectively. The t1/2 were(10.3±0.3)and(11.5±3.3)min,and the CLint were(420.1±10.9) and(573.4±188.2)ml/(min·kg),respectively. The apparent Km and Vmax for HLM and RLM were obtained and found to be(2.4±0.9) and(3.9±1.4)μmol/L,(1492±170.5)and(2783±595.8)nmol/(min·g protein),respectively. In RLM with UDPGA,38.5%of aloe emodin was metabolized in 30 min with t1/2 of 31.6 min and CLint of(197.1±15.5)ml/(min·kg). The results of CYP phenotyping indi?cated that CYP1A2,2B6,2C19 and 3A4 were the major enzymes involved in the metabolism of aloe emodin. By using the method of total normalized rate,the contributions of the major enzymes were assessed to be 35.4%,6.6%,2.2%and 21.9%,respectively. Con?clusion Aloe emodin is mainly eliminated by CYP mediated metabolism in HLM and RLM. CYP1A2 and 3A4 are the major responsi?ble enzymes of aloe emodin,and the contributions are above 20%. Species differences in liver metabolism of aloe emodin are observed. It undergoes notable glucuronidation in RLM only.
ABSTRACT
Objective To characterize the metabolic kinetics of aloe emodin in human liver microsomes(HLM)and rat liver microsomes(RLM)and identify the CYP phenotyping of phase-metabolism. Methods Aloe emodin was incubated at 37° with HLM and RLM in the presence or absence of NADPH, UDGPA or NADPH+UDGPA. The remaining aloe emodin was determined with a validated LC-MS/MS method to assess the metabolic stability and enzymatic kinetics. A panel of rCYP isoforms(CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4)and HLM with specific inhibitors of CYP isoforms were used to identify the CYP phenotyping of aloe emodin. Results In HLM and RLM, aloe emodin was metabolically eliminated in the presence of NADPH, with 85.8% and 81.7% of the parent compounds eliminated in 30 min, respectively. The t1/2 were(10.3±0.3)and(11.5±3.3)min, and the CLint were(420.1±10.9) and(573.4±188.2)ml/(min·kg), respectively. The apparent Km and Vmax for HLM and RLM were obtained and found to be(2.4±0.9) and(3.9±1.4)µmol/L, (1492±170.5)and(2783±595.8)nmol/(min·g protein), respectively. In RLM with UDPGA, 38.5% of aloe emodin was metabolized in 30 min with t1/2 of 31.6 min and CLint of(197.1±15.5)ml/(min·kg). The results of CYP phenotyping indicated that CYP1A2, 2B6, 2C19 and 3A4 were the major enzymes involved in the metabolism of aloe emodin. By using the method of total normalized rate, the contributions of the major enzymes were assessed to be 35.4%, 6.6%, 2.2% and 21.9%, respectively. Conclusion Aloe emodin is mainly eliminated by CYP mediated metabolism in HLM and RLM. CYP1A2 and 3A4 are the major responsible enzymes of aloe emodin, and the contributions are above 20%. Species differences in liver metabolism of aloe emodin are observed. It undergoes notable glucuronidation in RLM only.
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OBJECTIVE: To design and synthesize brain targeting danshensu (DSS) derivatives and study their metabolism in rat plasma and brain homogenate in vitro. METHODS: Tetramethylpyrazine and its derivatives were selected as carriers to design the brain targeting danshen suderivatives. Lipid-water partition coefficient (logf), brain blood concentration ratio (BB), and P-glycopro-tein affinity of the derivatives were predicted by some calculation softwares and the better compound DT3 was chosen for the next synthesis. The degradation of DT3 and its intermediate DTI in rat plasma and brain homogenate were measured by HPLC-UV. RESULTS: Two danshensu-pyrazine ester derivatives were synthesized, ie DTI and DT3. A simultaneous determination method of DT3, DTI, and (3,5,6-trimethylpyrazine-2-yl) methanol (TMPM) in rat plasma and brain homogenate was established. The degradation of DT3 in rat plasma and brain homogenate underwent the following process; DT3→DTl→the active metabolites of DSS and TMPM. Compared with DTI, the degradation of DT3 in rat plasma slowed down. The half-lives (t1/2) of TMPM were 1.68 and 1.71 min, respectively. Also, DT3 could quickly release the active metabolitein rat brain homogenate, and the concentration of TMPM showed a steady increase with a t1/2 of 222.88 min. CONCLUSION: The danshensu-pyrazine ester derivative DT3 has an extended t1/2 in rat plasma, and it can be degraded to active metabolite quickly in rat brain homogenate.
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0.05). Conclusions In human liver microsome system in vitro,CYP1A2,2B6 and CYP2A6 contribute to the metabolism of 629.It is very important for bioreduction drugs design and development,and provide the basic experimental and theoretical profiles for extensive application in clinic.