verapamil on the absorptive profile of aconitine. doi:10.1371/journal.pone.0124110.g006 Effect of a P-glycoprotein inhibitor on the level of aconitine in the rat gut sacs P-gp is an important glycoprotein in the intestinal mucous membrane epithelia. Because it can help pump medicine from the intestinal serosal side to the mucosal side, P-gp has a negative effect on the level of a majority of medicines. However, for toxic substances, P-glycoprotein might play a positive role. To determine the potential role of intestinal P-gp in the dynamic level of aconitine, verapamil, was added to a K-R solution that contained a high PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19768583/ concentration of aconitine. As shown in Fig 6, the content of aconitine increased when verapamil was added into every gut sac; in other words, the inhibition of intestinal P-gp by verapamil significantly increased the aconitine content in the rat intestine. Therefore, it can be deduced that aconitine is a potential substrate of P-glycoprotein. Effect of the Rhizoma Zingiberis extract on the level of P-gp substrates Because digoxin is a well-known substrate of P-glycoprotein, it was selected to be incubated with the Rhizoma Zingiberis extract to determine whether this extract could alter the level of digoxin. As shown in Fig 7, the digoxin content decreased in every gut sac when the Rhizoma Zingiberis extract was added; in other words, the Rhizoma Zingiberis extract decreased digoxin level in the rat intestine. Therefore, it 10 / 16 Qualitative and Quantitative Analysis of Natural Components by UPLC/MS Fig 7. Effect of the Rhizoma Zingiberis extract on the absorptive profile of digoxin. doi:10.1371/journal.pone.0124110.g007 can be deduced that the Rhizoma Zingiberis extract might be an inducer of P-glycoprotein. Furthermore, it can be deduced that the Rhizoma Zingiberis extract might decrease the conitine content by activating P-glycoprotein. Detection of gingerols in the Rhizoma Zingiberis PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19768759 extract 
The above results demonstrated that the Rhizoma Zingiberis extract reduced the level of aconitine in the rat gut sacs by inducing intestinal P-gp; however, the material basis was not determined. Therefore, the following experiments were purchase Luteolin 7-glucoside conducted to identify the main components of Rhizoma Zingiberis that affect aconitine levels in the rat gut sacs. Previous reports have suggested that the major bioactive constituents in Rhizoma Zingiberis are gingerols. In this section, the general components in the aqueous extract of Rhizoma Zingiberis were detected using UPLC/MSn, and the base peak chromatogram was shown in Fig 8. In Fig 8, eleven peaks were identified tentatively on the basis of their diagnostic ions and of a previous study, as shown in Effect of 6-gingerol on the level of aconitine in the rat gut sacs The experiment described in this section was conducted under the same conditions as decribed in the “Effect of the Rhizoma Zingiberis extract on the level of aconitine in the rat gut sacs” 11 / 16 Qualitative and Quantitative Analysis of Natural Components by UPLC/MS Fig 8. Base peak ion chromatogram of the extract of Rhizoma Zingiberis: blank solvent, 6-gingerol standard, and the Rhizoma Zingiberis extract. doi:10.1371/journal.pone.0124110.g008 section. The calculated Papp value of aconitine is shown in doi:10.1371/journal.pone.0124110.t007 12 / 16 Qualitative and Quantitative Analysis of Natural Components by UPLC/MS Fig 9. Effect of 6-gingerol on the absorptive profile of digoxin. doi:10.1371/journal.pone.0124110.g009 Effect