title: Impact of chrysosplenetin on the pharmacokinetics and anti-malarial efficacy of artemisinin against Plasmodium berghei as well as in vitro CYP450 enzymatic activities in rat liver microsome.
abstract: BACKGROUND
  Artemisinin (ART) is an efficacious and safe anti-malarial drugs but has low oral bioavailability and auto-induction profiles during multiple dosing. The pharmacokinetic disadvantages have been found to partially depend on the induction of cytochrome P-450 enzymes by ART and resulted in the therapeutic failure due to insufficient drug levels. The present study, therefore, investigated the impacts of chrysosplenetin (CHR), a polymethoxylated flavonoid from Artemisia annua, on the pharmacokinetics and the anti-malarial efficacy of ART against Plasmodium berghei. The inhibition of CHR on enzymatic activity of CYP1A2, CYP2A, CYP2C19, CYP2D6, CYP2E1, and CYP3A in rat liver microsome was also investigated. IC50, Km, Ki, and inhibitory type of CHR were respectively calculated.
  
  
  METHODS
  Twenty rats were randomly divided into four groups and received three-day oral doses of ART in absence or presence of CHR (in ratio of 1:0, 1:1, 1:2, and 1:4, respectively). Plasma samples were separately harvested for ART pharmacokinetics analysis using a valid liquid chromatography tandem mass spectrometric (LC-MS/MS) method. Female Kunming mice were inoculated by P. berghei K173 strain and pre-exposed to three-day oral administration of ART with or without CHR as pharmacokinetics protocol. Giemsa staining method was applied to calculate percent parasitaemia (%) and inhibition (%). In vitro rat liver microsomal model was employed to elucidate the inhibitory effect of CHR on CYP1A2, CYP2A, CYP2C19, CYP2D6, CYP2E1, and CYP3A.
  
  
  RESULTS
  The AUC0-t, Cmax, and t 1/2 of ART increased significantly (P < 0.05 or P < 0.01) as well as declined CLz (P < 0.05 or P < 0.01) after three-day oral doses of ART in presence of CHR (1:2) when compared with ART alone. Also, parasitaemia (%) remarkably attenuated 1.59 folds with 1.63-fold augmented inhibition (%) when the ratio between ART and CHR reached 1:2. CHR itself had no anti-malarial efficacy (P > 0.05). CHR inhibited in vitro activity of CYP1A2 and CYP2C19 (P < 0.01, IC50 = 4.61 and 6.23 μM) in a concentration-response manner. The inhibition did not emerge on CYP2E1 and CYP3A until the CHR concentration exceeded 4.0 μM (P < 0.01, IC50 = 28.17 and 3.38 µM). CHR has no impact on CYP 2A and CYP2D6 (P > 0.05). The inhibition types of CHR on CYP1A2 and CYP3A belonged to noncompetitive and uncompetitive, respectively.
  
  
  CONCLUSIONS
  Co-administration of ART with CHR in ratio of 1:2 achieved a synergic anti-malarial effect partly because of the noncompetitive or uncompetitive inhibition of CHR of drug-metabolism enzymes, especially CYP3A which is closely related to the auto-induction of ART.
authors.affiliation: School of Pharmacy, Ningxia Medical University, 1160# Shengli Street, Xingqing District, Yinchuan, 750004, People's Republic of China. 378482625@qq.com.|Institute of Clinical Pharmacology, General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China. 378482625@qq.com.
authors.forename: Shijie
authors.initials: S
authors.lastname: Wei
authors.affiliation: Institute of Clinical Pharmacology, General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China. 894495249@qq.com.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Ji
authors.affiliation: School of Pharmacy, Ningxia Medical University, 1160# Shengli Street, Xingqing District, Yinchuan, 750004, People's Republic of China. 284938703@qq.com.
authors.forename: Bei
authors.initials: B
authors.lastname: Yang
authors.affiliation: School of Pharmacy, Ningxia Medical University, 1160# Shengli Street, Xingqing District, Yinchuan, 750004, People's Republic of China. 465582600@qq.com.
authors.forename: Liping
authors.initials: L
authors.lastname: Ma
authors.affiliation: Institute of Epidemic Disease, Academy of Military Medical Sciences, Beijing, People's Republic of China. beizhuchun@hotmail.com.
authors.forename: Zhuchun
authors.initials: Z
authors.lastname: Bei
authors.affiliation: School of Pharmacy, Ningxia Medical University, 1160# Shengli Street, Xingqing District, Yinchuan, 750004, People's Republic of China. 132400@sina.com.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Clinical Pharmacology, General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China. dhwbeining@163.com.
authors.forename: Hongwan
authors.initials: H
authors.lastname: Dang
authors.affiliation: Institute of Clinical Pharmacology, General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China. 932711474@qq.com.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Yang
authors.affiliation: School of Pharmacy, Ningxia Medical University, 1160# Shengli Street, Xingqing District, Yinchuan, 750004, People's Republic of China. lc389476050@qq.com.
authors.forename: Cheng
authors.initials: C
authors.lastname: Liu
authors.affiliation: School of Pharmacy, Ningxia Medical University, 1160# Shengli Street, Xingqing District, Yinchuan, 750004, People's Republic of China. Wu.xiuli2005@163.com.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Wu
authors.affiliation: School of Pharmacy, Ningxia Medical University, 1160# Shengli Street, Xingqing District, Yinchuan, 750004, People's Republic of China. chenjing2005@126.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000493:pharmacokinetics / Q000494:pharmacology*; D037621:Artemisinins / Q000493:pharmacokinetics / Q000494:pharmacology*; D002853:Chromatography, Liquid; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics*; D005260:Female; D005419:Flavonoids / Q000494:pharmacology*; D008288:Malaria / Q000188:drug therapy*; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010949:Plasma / Q000737:chemistry; D010962:Plasmodium berghei / Q000187:drug effects; D017207:Rats, Sprague-Dawley; D053719:Tandem Mass Spectrometry; D016896:Treatment Outcome
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D003577:Cytochrome P-450 Enzyme System; C570121:chrysosplenetin; C031327:artemisinin