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Bioactivity-guided fractionation of an antidiarrheal Chinese herb Rhodiola kirilowii (Regel) Maxim reveals (-)-epicatechin-3-gallate and (-)-epigallocatechin-3-gallate as inhibitors of cystic fibrosis transmembrane conductance regulator.

Chen L, Yu B, Zhang Y, Gao X, Zhu L, Ma T, Yang H - PLoS ONE (2015)

Bottom Line: However, the active ingredients responsible for their therapeutic effectiveness remain unknown.In an intestinal closed-loop model in mice, intraluminal application of EGCG (10 μg) and ECG (10 μg) significantly reduced cholera toxin-induced intestinal fluid secretion.CFTR Cl- channel is a molecular target of natural compounds EGCG and ECG.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, Liaoning Normal University, Dalian, 116029, P. R. China.

ABSTRACT
Cystic fibrosis transmembrane conductance regulator (CFTR) is the principal apical route for transepithelial fluid transport induced by enterotoxin. Inhibition of CFTR has been confirmed as a pharmaceutical approach for the treatment of secretory diarrhea. Many traditional Chinese herbal medicines, like Rhodiola kirilowii (Regel) Maxim, have long been used for the treatment of secretory diarrhea. However, the active ingredients responsible for their therapeutic effectiveness remain unknown. The purpose of this study is to identify CFTR inhibitors from Rhodiola kirilowii (Regel) Maxim via bioactivity-directed isolation strategy. We first identified fractions of Rhodiola kirilowii (Regel) Maxim that inhibited CFTR Cl- channel activity. Further bioactivity-directed fractionation led to the identification of (-)-epigallocatechin-3-gallate (EGCG) as CFTR Cl- channel inhibitor. Analysis of 5 commercially available EGCG analogs including (+)-catechins (C), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG) and EGCG revealed that ECG also had CFTR inhibitory activity. EGCG dose-dependently and reversibly inhibited CFTR Cl- channel activity in transfected FRT cells with an IC50 value around 100 μM. In ex vivo studies, EGCG and ECG inhibited CFTR-mediated short-circuit currents in isolated rat colonic mucosa in a dose-dependent manner. In an intestinal closed-loop model in mice, intraluminal application of EGCG (10 μg) and ECG (10 μg) significantly reduced cholera toxin-induced intestinal fluid secretion. CFTR Cl- channel is a molecular target of natural compounds EGCG and ECG. CFTR inhibition may account, at least in part, for the antidiarrheal activity of Rhodiola kirilowii (Regel) Maxim. EGCG and ECG could be new lead compounds for development of CFTR-related diseases such as secretory diarrhea.

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CFTR inhibition by EGCG and ECG.A. Dose—response relationship of EGCG and ECG determined in the iodide influx assay. Data were expressed as mean±SE, n = 3). B. EGCG and ECG inhibition short-circuit current after amiloride and indomethacin addition and stimulation by FSK (20 μM) in isolated rat colonic mucosa. EGCG and ECG were added to mucosal surfaces as indicated. One experiment typical of four or five is shown.
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pone.0119122.g005: CFTR inhibition by EGCG and ECG.A. Dose—response relationship of EGCG and ECG determined in the iodide influx assay. Data were expressed as mean±SE, n = 3). B. EGCG and ECG inhibition short-circuit current after amiloride and indomethacin addition and stimulation by FSK (20 μM) in isolated rat colonic mucosa. EGCG and ECG were added to mucosal surfaces as indicated. One experiment typical of four or five is shown.

Mentions: CFTR is expressed in the crypt cells in the distal small intestine and colon, and it is the major pathway for Cl- secretion into intestinal lumen [4, 27]. The efficacies of EGCG and ECG were tested ex vivo in isolated rat colonic mucosa by Ussing chamber short-circuit assay with CFTRinh-172 as a positive control. Amiloride (10 μM) and indomethacin (10 μM) were present in the chamber solutions for entire experimental periods to prevent Na+ current and prostaglandin generation. As shown in Fig. 5, EGCG and ECG dose-dependently inhibited short-circuit currents in intact rat colonic mucosa.


Bioactivity-guided fractionation of an antidiarrheal Chinese herb Rhodiola kirilowii (Regel) Maxim reveals (-)-epicatechin-3-gallate and (-)-epigallocatechin-3-gallate as inhibitors of cystic fibrosis transmembrane conductance regulator.

Chen L, Yu B, Zhang Y, Gao X, Zhu L, Ma T, Yang H - PLoS ONE (2015)

CFTR inhibition by EGCG and ECG.A. Dose—response relationship of EGCG and ECG determined in the iodide influx assay. Data were expressed as mean±SE, n = 3). B. EGCG and ECG inhibition short-circuit current after amiloride and indomethacin addition and stimulation by FSK (20 μM) in isolated rat colonic mucosa. EGCG and ECG were added to mucosal surfaces as indicated. One experiment typical of four or five is shown.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4352019&req=5

pone.0119122.g005: CFTR inhibition by EGCG and ECG.A. Dose—response relationship of EGCG and ECG determined in the iodide influx assay. Data were expressed as mean±SE, n = 3). B. EGCG and ECG inhibition short-circuit current after amiloride and indomethacin addition and stimulation by FSK (20 μM) in isolated rat colonic mucosa. EGCG and ECG were added to mucosal surfaces as indicated. One experiment typical of four or five is shown.
Mentions: CFTR is expressed in the crypt cells in the distal small intestine and colon, and it is the major pathway for Cl- secretion into intestinal lumen [4, 27]. The efficacies of EGCG and ECG were tested ex vivo in isolated rat colonic mucosa by Ussing chamber short-circuit assay with CFTRinh-172 as a positive control. Amiloride (10 μM) and indomethacin (10 μM) were present in the chamber solutions for entire experimental periods to prevent Na+ current and prostaglandin generation. As shown in Fig. 5, EGCG and ECG dose-dependently inhibited short-circuit currents in intact rat colonic mucosa.

Bottom Line: However, the active ingredients responsible for their therapeutic effectiveness remain unknown.In an intestinal closed-loop model in mice, intraluminal application of EGCG (10 μg) and ECG (10 μg) significantly reduced cholera toxin-induced intestinal fluid secretion.CFTR Cl- channel is a molecular target of natural compounds EGCG and ECG.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, Liaoning Normal University, Dalian, 116029, P. R. China.

ABSTRACT
Cystic fibrosis transmembrane conductance regulator (CFTR) is the principal apical route for transepithelial fluid transport induced by enterotoxin. Inhibition of CFTR has been confirmed as a pharmaceutical approach for the treatment of secretory diarrhea. Many traditional Chinese herbal medicines, like Rhodiola kirilowii (Regel) Maxim, have long been used for the treatment of secretory diarrhea. However, the active ingredients responsible for their therapeutic effectiveness remain unknown. The purpose of this study is to identify CFTR inhibitors from Rhodiola kirilowii (Regel) Maxim via bioactivity-directed isolation strategy. We first identified fractions of Rhodiola kirilowii (Regel) Maxim that inhibited CFTR Cl- channel activity. Further bioactivity-directed fractionation led to the identification of (-)-epigallocatechin-3-gallate (EGCG) as CFTR Cl- channel inhibitor. Analysis of 5 commercially available EGCG analogs including (+)-catechins (C), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG) and EGCG revealed that ECG also had CFTR inhibitory activity. EGCG dose-dependently and reversibly inhibited CFTR Cl- channel activity in transfected FRT cells with an IC50 value around 100 μM. In ex vivo studies, EGCG and ECG inhibited CFTR-mediated short-circuit currents in isolated rat colonic mucosa in a dose-dependent manner. In an intestinal closed-loop model in mice, intraluminal application of EGCG (10 μg) and ECG (10 μg) significantly reduced cholera toxin-induced intestinal fluid secretion. CFTR Cl- channel is a molecular target of natural compounds EGCG and ECG. CFTR inhibition may account, at least in part, for the antidiarrheal activity of Rhodiola kirilowii (Regel) Maxim. EGCG and ECG could be new lead compounds for development of CFTR-related diseases such as secretory diarrhea.

Show MeSH
Related in: MedlinePlus