Inhibition by Apple Polyphenols of ADP‐Ribosyltransferase Activity of Cholera Toxin and Toxin‐Induced Fluid Accumulation in Mice

Abstract

The effects of crude polyphenol extracted from immature apples on the enzymatic and biological activities of a cholera toxin (CT) were investigated. When the apple polyphenol extract (APE) was examined for properties to inhibit CT‐catalyzed ADP‐ribosylation of agmatine, it was found that APE inhibited it in a dose‐dependent manner. The concentration of APE to inhibit 50% of the enzymatic activity of CT (15 μg/ml) was approximately 8.7 μg/ml. The APE also diminished CT‐induced fluid accumulation in two diarrhea models for in vivo mice. In the ligated ileum loops, 25 μg of APE significantly inhibited fluid accumulation induced by 500 ng of CT. In a sealed mouse model, even when APE was administered orally 10 min after a toxin injection, fluid accumulation was significantly inhibited at a comparable dosage. Lineweaver‐Burk analysis demonstrated that APE had negative allosteric effects on CT‐catalyzed NAD: agmatine ADP‐ribosyltransferase. We fractionated the APE into four fractions using LH‐20 Sephadex resin. One of the fractions, FAP (fraction from apple polyphenol) 1, which contains non‐catechin polyphenols, did not significantly inhibit the CT‐catalyzed ADP‐ribosylation of agmatine. FAP2, which contains compounds with monomeric, dimeric, and trimeric catechins, inhibited the ADP‐ribosylation only partially, but significantly. FAP3 and FAP4, which consist of highly polymerized catechin compounds, strongly inhibited the ADP‐ribosylation, indicating that the polymerized structure of catechin is responsible for the inhibitory effect that resides in APE. The results suggest that polymerized catechin compounds in APE inhibit the biological and enzymatic activities of CT and can be used in a precautionary and therapeutic manner in the treatment of cholera patients.

Development of a High Performance Liquid Chromatographic Method for Systematic Quantitative Analysis of Chemical Constituents in Rhubarb

“…It has been reported that 29 has psychotropic and anti-cholera toxin activities, 17,18) and 30 possesses a blood urea nitrogen-decreasing activity. 13) Thus, much attention has been paid to detailed quantitative information regarding the polymeric procyanidins in rhubarb.…”

“…), jaundice, diarrhea and food poisoning, in addition to constipation. Although various individual pharmacological effects related to the above treatments, such as purgative activity, 2,3) anti-bacterial and anti-fungal activities, 4) anti-tumor activity, 5) anti-inflammatory and analgesic activities, 6,7) improvement of renal disorders, [8][9][10][11] improvement of nitrogen metabolism, 12,13) psychotropic activity, 14) anti-allergic effects, 15,16) anti-cholera toxin activity, 17,18) promoting blood circulation and removing blood stasis, 19) and the various involved active compounds have been reported, comprehensive chemical study of the composition of bioactive constituents of rhubarb has been rare. Kashiwada et al 20) set up a HPLC method to analyze almost all the phenolic compounds simultaneously, and reported that the majority of the compounds could be separated by a 0.05 M H 3 PO 4 solution-acetonitrile gradient elution system.…”

Polyphenols and gastrointestinal diseases

“…A polyphenol extract from apples was found to have an inhibitory effect on cholera toxin induced diarrhea, in a dose-dependent fashion [13]. This effect could be seen as long as 10 min after toxin injection.…”

Differential Activities of Plant Polyphenols on the Binding and Internalization of Cholera Toxin in Vero Cells

“…It appears that the GM1-binding site of CTB was not masked by interaction with RG-tannin, although complex formation did affect CT internalization. ACT was more potent than applephenon for both inhibition of CT binding and precipitation of CT, which may explain why ACT was more effective than applephenon in inhibiting of CT ADP-ribosyl transferase activity (14). The different interactions of RG-tannin and other polyphenols with CT may reflect the presence in RG-tannin, but not in applephenon and HBT, of galloyl moieties.…”

“…These include applephenon, HBT, and RG-tannin, derived from apple, hop bract, and Daio (Rhei rhizoma), respectively. RG-tannin and applephenon suppress CTcatalyzed ADP-ribosylation and CT-induced fluid accumulation in rabbit or mouse ileal loops (14,15). RG-tannin is most likely a procyanidine polymer (mainly 8-mer) containing galloyl groups.…”