Quantitation Assay for Absorption and First-Pass Metabolism of Emodin in Isolated Rat Small Intestine Using Liquid Chromatography-Tandem Mass Spectrometry

Abstract

Polyphenols, a group of complex naturally occurring compounds, are widely distributed throughout the plant kingdom and thus are readily consumed by humans.1,2) As members of the polyphenol family, dietary anthraquinones have received much attention as potential protectors against a variety of human diseases, in particular cardiovascular disease and cancer.3,4) Emodin (1,3,8-trihydroxy-6-methylanthraquinone), the active components of many herbal laxatives such as aloe, senna, cascara sagrada, and rhubarb, belongs to the anthraquinone family. 5,6) Intestinal absorption is a prerequisite for a possible causal relationship between emodin intake and its proposed chemopreventive action. However, our limited knowledge of how emodin is absorbed and metabolized has hampered our understanding of its effect in the body. In addition, some similar compounds have poor bioavailability due to weak absorption and significant degradation by enzymes. 7) Furthermore, to date, information on in vivo absorption and metabolism of emodin is scarce-there are no reports of evidence of extensive first-pass metabolism of emodin in the gut-and thus intestinal handling of emodin requires further investigation to appraise its beneficial action in vivo.To address this issue, we evaluated the contribution of the small intestine to the absorption and first-pass metabolism of emodin using an isolated rat small intestine perfusion model. This model facilitates direct investigation of luminal disappearance and venous appearance of administered emodin and analyses the metabolites in both perfusate and mesenteric blood, thereby allowing the direct estimation of intestinal absorption and first-pass metabolism of this drug. 8,9) MATERIALS AND METHODS Reagents and ChemicalsEmodin and chrysophanol was purchased from the National Institute for the Control of Pharmaceutical and Biological Products (Beijing, China) at the highest purity available (98%, as determined by HPLC). Emodin was dissolved in DMSO (0.1% v/v final concentration) because it is hydrophobic and poorly soluble in water. b-Glucuronidase (catalog no. G-0251) and sulfatase (catalog no. S-9754) were purchased from Sigma. All chemicals and reagents used were of analytical grade or HPLC grade.Animals Male Sprague-Dawley rats (70-110 d old) weighing between 270 and 320 g were obtained from the experimental animal center of the Fourth Military Medical University, Xi'an, China. The rats were fasted overnight with free access to water before the day of the experiment.Animal Surgery The rats were anesthetized with an intra-abdominal injection of a mixture containing 40 mg/kg phenobarbital sodium. The animals were then heparinized (90 U/kg Ϫ1 ) via the vena caudalis. During surgery, the body temperature was maintained at 37°C by a heating lamp.The small intestine was prepared as described. [10][11][12] Figure 1 schematically illustrates the vascular-luminal perfused rat intestine preparation. Briefly, the small intestine was exposed by midline incision, and a 7-to 11-cm-long segment of the intestin...

Bioconcentration and Metabolism of Emodin in Zebrafish Eleutheroembryos

“…In the modified test, the accumulation rates of metabolites were fast at first and turned slow subsequently. These results showed that emodin could be highly metabolized in vivo , which is in agreement with the previous studies performed in mammals (Teng et al, 2007; Liu et al, 2012). No metabolite was detected in the media probably due to their low concentrations that were below the low limit of detection.…”

“…For quantification in multiple-reaction monitoring (MRM) cone voltage, collision energy and precursor to production transition m/z for emodin and IS were as shown in Table 1. For metabolism study of emodin, three phase II metabolites of emodin were monitored simultaneously using MRM mode (Teng et al, 2007). …”

Berberine increases the expression of NHE3 and AQP4 in sennosideA-induced diarrhoea model

“…Isolated intestine animal model and sample were prepared according to the methods of Teng ZH et al [28]. The mouse intestine was exposed and separated by midline incision.…”

Liquid Chromatography/Positive-Ion Electrospray Tandem Mass Spectrometry Assay for Nisoldipine in Human Plasma and Its Application to a Pharmacokinetic Study

“…[10,11] Herein, we developed a rapid, sensitive, and specific LC-MS-MS method with positive ion detection mode (ESI þ ) for quantifying nisoldipine in human plasma with nimodipine as the internal standard (IS) and successfully applied it to pharmacokinetics studies of nisoldipine.…”