Procyanidin C1 from apple extracts inhibits Fc epsilon RI-mediated mast cell activation.

BACKGROUND: Polyphenol-enriched fractions, which are extracted from unripe apples (Rosaceae, Malus spp.), consisting of procyanidins (polymers of catechins) are known to have an anti-allergenic effect on patients with various allergic diseases. Although it has been reported that apple extracts inhibit histamine release from mast cells, the molecular mechanisms for this anti-allergenic effect are not well understood. To elucidate the molecular mechanisms by which apple extracts induce their anti-allergenic effects, the effects of purified apple extract components on high-affinity receptors for IgE (Fc epsilon RI)-mediated mast cell activation were investigated. METHODS: The anti-allergic effect of oral administration of apple procyanidin extracts on passive cutaneous anaphylactic responses of BALB/c mice was assessed. We evaluated the effects of procyanidin C1 (PC1) [epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-epicatechin], a component of the procyanidin fraction, on mouse bone-marrow-derived mast cell degranulation, cytokine production, protein tyrosine phosphorylation and on the generation of intracellular reactive oxygen species (ROS) of cells stimulated by Fc epsilon RI cross-linking in vitro. RESULTS: In an in vivo study, oral administration of the procyanidin fraction suppressed the mast-cell-dependent allergic reaction. In in vitro studies, PC1 dose-dependently decreased Fc epsilon RI-mediated degranulation and cytokine production of mast cells. Furthermore, PC1 inhibited tyrosine phosphorylation of Syk and linker for activation of T cells, and the ROS generation in stimulated mast cells. CONCLUSIONS: PC1 suppresses Fc epsilon RI-mediated mast cell activation by inhibiting intracellular signaling pathways. These observations provide evidence for the anti-allergenic effects of the procyanidin-enriched apple extract.

Hop polyphenols suppress production of water-insoluble glucan by Streptococcus mutans and dental plaque growth in vivo.

OBJECTIVE: This study determined the effect of Hop polyphenols (HPP) on water-insoluble glucan (WIG), which is a major component of dental plaque along with microorganisms, and the effect of HPP-containing tablets on the growth of dental plaque. METHODS: The effects of HPP on Streptococcus mutans MT8148 were determined. HPP concentrations employed in this study were 0% (as the HPP control), 0.001%, 0.01%, 0.1%, and 0.5%. The average result of six independent experiments was obtained at each concentration of HPP. Suppression of plaque formation in vivo was examined by a clinical trial that was designed as a randomized, single-blind, three-treatment study using 28 healthy subjects. The subjects used either 20 mg or seven mg HPP-containing tablets representing high and low dosages, respectively. The composition of each tablet was similar, except for the level of HPP; the control tablet had none. For the treatment period, subjects took one tablet seven times a day (before breakfast, after each meal, between meals, and at bedtime) for three days. The tablets were dissolved in the mouth and naturally swallowed. Plaque levels were then assessed for the subjects in the three groups. RESULTS: In vitro, after 24-hour incubation, 0.5% HPP significantly reduced the growth of S. mutans compared to the control (p < 0.01). After 18-hour incubation, HPP at 0.1% and 0.5% significantly reduced lactic acid production (p < 0.05 and p < 0.001, respectively), and HPP at 0.01%, 0.1%, and 0.5% also suppressed WIG production (p < 0.01, p < 0.001 and p < 0.001, respectively). In vivo, the effect of HPP-containing tablets (seven times a day) on three-day dental plaque regrowth was assessed by the plaque scoring system (PSS). The high-dosage group using 20 mg HPP tablets exhibited a reduction in PSS (1.37 +/- 0.48 vs. 2.41 +/- 1.15 in the control group, p < 0.05). CONCLUSION: It was concluded that HPP tablets might be a significant means of delivering HPP onto tooth surfaces to prevent dental plaque formation.

Oligomeric procyanidins in apple polyphenol are main active components for inhibition of pancreatic lipase and triglyceride absorption.

Inhibitory effects of apple polyphenol extract (AP) and procyanidin contained in AP on in vitro pancreatic lipase activity and in vivo triglyceride absorption in mice and humans were examined. AP and procyanidin considerably inhibited in vitro pancreatic lipase activity. However, polyphenols, except for procyanidin, in AP (i.e., catechins, chalcones, and phenol carboxylic acids) showed weak inhibitory activities on pancreatic lipase. Procyanidins separated by normal-phase chromatography according to the degree of polymerization were also examined. Inhibitory effects of procyanidins increased according to the degree of polymerization from dimer to pentamer. On the other hand, pentamer or greater procyanidins showed maximal inhibitory effects on pancreatic lipase. These results suggested that with respect to in vitro pancreatic lipase inhibition, the degree of polymerization was an important factor and oligomeric procyanidin mainly contributed. Next, we performed a triglyceride tolerance test in mice and humans. Simultaneous ingestion of AP and triglyceride significantly inhibited an increase of plasma triglyceride levels in both models. These results suggested that the oligomeric procyanidins contained in AP inhibited triglyceride absorption by inhibiting pancreatic lipase activity in mice and humans.

Safety evaluation of polyphenols extracted from hop bracts.

Hop bract polyphenols contain polyphenols as promising functional ingredients. To assess the safety of topical hop bract polyphenols, Hopsphenon, we examined acute, 14-day, 28-day and 90-day toxicity tests in rats, and mutagenicity tests using Ames test and micronucleus test in mice. The acute, 14-day, 28-day and 90-day toxicity tests revealed that Hopsphenon produced no symptoms of significant injury. The lethal dose of hop bract polyphenols is greater than 2000 mg/kg. The Ames test in the absence of S9 mix for TA98 and in the presence of S9 mix for TA1537 revealed that Hopsphenon had slight mutagenicity at a high dose of 5000 microg/plate; however, in the micronucleus test, Hopsphenon was negative. These tests demonstrated that hop bract polyphenols are safe and do not cause any detrimental effects in vivo under the conditions investigated in this study.

Characteristics and physiological functions of polyphenols from apples.

Apples contain many kinds of polyphenols, and the main components are oligomeric procyanidins. Applephenon is apple polyphenol extract produced commercially from unripe apples, and has been used as food additive in order to prevent oxidation of components in foods and its application in functional foods is expected. In a lipid metabolism regulation study, administration of Applephenon has the potential to exert strong anti-oxidative activity and to inhibit consumption of vitamin E and anti-oxidative enzymes. Double blind clinical trials of Applephenon on pediatric patients with atopic dermatitis, and tests using type I allergic model mice suggested that Applephenon might regulate allergic reactions. We found the no observed adverse effect level (NOAEL) of Applephenon is greater than 2000 mg/kg in a 90~day consecutive oral administration toxicity test in rats, and Applephenon is safe and acceptable based on mutagenicity tests.

Evaluation of safety of excessive intake and efficacy of long-term intake of beverages containing apple polyphenols.

In the present study, a randomized, double-blind, placebo-controlled study was performed to evaluate the safety of an excessive intake and the efficacy of a long-term intake of polyphenols derived from apples for moderately underweight to moderately obese subjects (long-term intake: 94 subjects; excessive intake: 30 subjects). For each trial, the subjects were divided into the following two groups: a group that drank beverages with apple polyphenols (600 mg) (hereinafter referred to as the apple group) and a group that drank beverages without apple polyphenols (hereinafter referred to as the placebo group). For the long-term intake trial, the subjects were given a regular amount of the beverage (340 g) each day for 12 weeks. For the excessive intake trial, the subjects were given three times the regular amount of the beverage each day for 4 weeks. It is noteworthy that the visceral fat area (VFA) of subjects in the apple group for the long-term intake trial had decreased significantly by the 8- and 12-week marks (week 8: p < 0.05; week 12: p < 0.01) compared to the baseline (week 0). The degree of change in VFA experienced by subjects in the apple group compared to those in the placebo group was significantly lower by the 8- and 12-week marks (p < 0.01). Stratified analysis indicated that the VFA of subjects in the apple group that started with a high VFA (VFA > or = 100 cm(2)) had decreased significantly by the 8- and 12-week marks compared to the baseline (week 8: p < 0.05; week 12: p < 0.01). However, no significant change in the VFA of subjects in the apple group that started with a normal VFA (VFA < 100 cm(2)) was exhibited by the 8- and 12-week marks. No clinical problems arose in the blood examinations or physical examinations for the long-term intake trial or the excessive intake trial. No adverse reaction was observed in either trial. These results demonstrated the efficacy and the safety of the beverage with apple polyphenols.

Apple polyphenols influence cholesterol metabolism in healthy subjects with relatively high body mass index.

We performed a randomized double-blind, placebo-controlled study on moderately obese male and female subjects (71 subjects) with a body mass index ranging from 23 to 30 to evaluate the efficacy of 12-week intake of polyphenols extracted from apples and hop bract (600 mg/day). We confirmed that 12-week ingestion of polyphenol-containing capsules significantly decreased total cholesterol and LDL-cholesterol levels. The effects of the apple polyphenol-containing capsules were more marked than those of the hop bract polyphenol-containing capsules. The visceral fat area and the level of adiponectin in the group administered apple polyphenols improved in comparison with the control group. Blood and physical examinations revealed on clinical problems, and no adverse reactions were observed during the ingestion period. These results demonstrate that apple polyphenols regulate fat metabolism in healthy subjects with relatively high body mass index.

Inhibitory effect of polyphenol-enriched apple extracts on mast cell degranulation in vitro targeting the binding between IgE and FcepsilonRI.

Extracts from immature fruit of the apple (Rosaceae, Malus sp.), which contain procyanidins (polymers of catechins) as the major ingredients, are known to inhibit histamine release from mast cells. We analyzed in this study the mechanism for the anti-allergic activity of two polyphenol-enriched apple extracts. These extracts, termed "crude apple polyphenol (CAP)" and "apple condensed tannin (ACT)", reduced the degranulation of mast cells caused by cross-linking of the high-affinity receptor for IgE (FcepsilonRI) with IgE and the antigen in a dose-dependent manner. Furthermore, western blotting revealed that phosphorylation of the intracellular signal-transduction molecules caused by cross-linking of FcepsilonRI was markedly decreased by the addition of CAP or ACT. We then analyzed the effects of CAP and ACT on the binding of the IgE antibody to FcepsilonRI on mast cells, which is the first key step in the allergic reaction mediated by mast cells, and found that this binding was markedly inhibited by both CAP and ACT. These results indicate that the inhibition of binding between FcepsilonRI and IgE by either CAP or ACT was the probable cause of the suppression of mast cell activation. This is the first report demonstrating the molecular mechanism for the anti-allergic effect of procyanidin-enriched extracts from apples.