ABSTRACT
Rotundine (1 micromol L(-1)) was incubated with a panel of rCYP enzymes (1A2, 2C9, 2C19, 2D6 and 3A4) in vitro. The remained parent drug in incubates was quantitatively analyzed by an Agilent LC-MS. CYP2C19, 3A4 and 2D6 were identified to be the isoenzymes involved in the metabolism of rotundine. The individual contributions of CYP2C19, 3A4 and 2D6 to the rotundine metabolism were assessed using the method of total normalized rate to be 31.46%, 60.37% and 8.17%, respectively. The metabolites of rotundine in incubates were screened with ESI-MS at selected ion mode, and were further identified using MS2 spectra and precise molecular mass obtained from an Agilent LC/Q-TOF-MSMS, as well as MS(n) spectra of LC-iTrap-MS(n). The predominant metabolic pathway of rotundine in rCYP incubates was O-demethylation. A total 5 metabolites were identified including 4 isomerides of mono demethylated rotundine and one di-demethylated metabolite. The results also showed that CYP2C19, 2D6 and 3A4 mediated O-demethylation of methoxyl groups at different positions of rotundine. Furthermore, the ESI-MS cleavage patterns of rotundine and its metabolites were explored by using LC/Q-TOF-MSMS and LC/iTrap-MS(n) techniques.
Subject(s)
Berberine Alkaloids/metabolism , Cytochrome P-450 Enzyme System/metabolism , Analgesics, Non-Narcotic/metabolism , Aryl Hydrocarbon Hydroxylases/metabolism , Chromatography, Liquid , Cytochrome P-450 CYP1A2/metabolism , Cytochrome P-450 CYP2C19 , Cytochrome P-450 CYP2C9 , Cytochrome P-450 CYP2D6/metabolism , Cytochrome P-450 CYP3A/metabolism , Dopamine Antagonists/metabolism , Humans , Isoenzymes/metabolism , Methylation , Recombinant Proteins/metabolism , Spectrometry, Mass, Electrospray IonizationABSTRACT
OBJECTIVE: To investigate effect of demethoxycurcumin on stability of curcumin. METHODS: To add the demethoxycurcumin to pure curcumin, the change of curcumin was determined by HPLC and the dynamics of curcumin degradation was investigated. RESULT: The stability both obtained from alcohol and demethoxycurcumin improved the stabilization of curcumin, the demi-period of curcumin prolonged with the addition of demethoxycurcumin. CONCLUSION: The commixture of curcumin and demethoxycurcumin are more stable than pure curcumin at the same conditions. Stability of curcumin is improved by demethoxycurcumin,it is crude stabilizing agent.