Effect of carbon dioxide in carbonated drinks on linguapalatal swallowing pressure.

This study aimed to investigate the influence of carbonated drinks with gas volumes (GV) of 0, 1.5, and 2.7 on linguapalatal swallowing pressure, intraoral carbonation perception, and maximum velocity of a bolus through the pharynx in healthy volunteers (N = 20, all female, age range; 20-21 years). The volunteers swallowed a 12-mL drink in the natural state. Linguapalatal swallowing pressure was measured using a special sensor sheet, and maximum velocity of the bolus through the pharynx was measured using ultrasonic diagnostic imaging equipment. Peak magnitude, integrated value, and duration of linguapalatal swallowing pressure and maximum velocity of a liquid bolus through the pharynx increased with an increase in carbon dioxide content in the carbonated drink. The total integrated values of carbonated drinks with GV of 1.5 and 2.7 were larger than that of the drink without carbon dioxide. These results suggest that the carbon dioxide dissolved in carbonated drinks influences the activity of taste receptors in the mouth and results in neuromotor responses.

Relation between the rheological properties and the swallowing characteristics of vegetable juices fortified with carrot puree.

The relation between the rheological properties and the swallowing characteristics of vegetable juices fortified with 0-30.0% carrot puree (CP) was evaluated. The apparent viscosity of vegetable juices increased with increasing CP concentrations, and a increases in yield stress were observed at and above 17.5% CP. In a sensory evaluation, texture perceived in the oral cavity varied as between vegetable juices with >17.5% CP and those with <12.5% CP. The maximum velocity in the pharyngeal region was classified into three same-quality subgroups: vegetable juices with 0-12.5% CP, with 10.0-25.0% CP, and with 17.5-30.0% CP. It significantly decreased with increasing CP concentrations.

Black tea theaflavins suppress dioxin-induced transformation of the aryl hydrocarbon receptor.

Dioxins cause various adverse effects through transformation of aryl hydrocarbon receptor (AhR). In this study, we investigated whether black tea extract and its components, theaflavins, suppress AhR transformation in vitro. First, we confirmed that black tea extract strongly suppressed AhR transformation compared to green and oolong tea, although the catechin contents did not change significantly among the extracts. Then we isolated four theaflavins as active compounds from black tea leaves. They suppressed 1 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced AhR transformation in a dose-dependent manner. The IC(50) values of theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate, and theaflavin-3,3'-digallate (Tfdg) were 4.5, 2.3, 2.2, and 0.7 muM, respectively. The suppressive effect of Tfdg was observed not only by pre-treatment but also by post-treatment. This suggests that theaflavins inhibit the binding of TCDD to the AhR and also the binding of the transformed AhR to the specific DNA-binding site as putative mechanisms.

Pigments in green tea leaves (Camellia sinensis) suppress transformation of the aryl hydrocarbon receptor induced by dioxin.

Environmental contaminants such as dioxins enter the body mainly through diet and cause various toxicities through transformation of the aryl hydrocarbon receptor (AhR). We previously reported that certain natural flavonoids at the dietary level suppress the AhR transformation induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In this study, we identified lutein and chlorophyll a and b from green tea leaves as the novel antagonists for AhR. These active compounds suppressed AhR transformation dose-dependently with the 50% inhibitory concentration (IC(50)) values against 0.1 nM TCDD-induced AhR transformation at 3.2, 5.0, and 5.9 microM, respectively. (-)-Epigallocatechin gallate, which is the most abundant flavonoid in green tea leaves, also showed stronger suppressive effects than did other major tea components, with the IC(50) value of 1.7 microM. Thus, these pigments of green tea leaves have the potential to protect from dioxin toxicity through the suppression of AhR transformation.

Black tea extract suppresses transformation of aryl hydrocarbon receptor induced by dioxin.

Dioxins cause various adverse effects through binding to an aryl hydrocarbon receptor (AhR) and transformation of the receptor. In this study, we investigated whether black tea extract suppresses AhR transformation. Dried black tea leaves were extracted with 75% ethanol, and the extract was pretreated to the rat liver cytosol fraction 10 min prior to addition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Transformed AhR was detected by electrophoretic gel mobility shift assay. Black tea extract suppressed AhR transformation in a dose-dependent manner, and the IC50 value against 1 nM TCDD-induced AhR transformation was 8.9 microg/ml. The result suggests that intake of black tea has a potential to suppress the AhR transformation, leading protection from dioxin toxicity.

[Isolation and determination of an antidote for botulinum neurotoxin from black tea extract].

The botulinum neurotoxin produced by Clostridium botulinum exhibits the strongest neurotoxicity, and causes botulism in mammals. We have found an inactivator for clostridial neurotoxins in black tea extract (thearubigin fraction) as a natural foodstuff. In this study, we have isolated and identified the inactivators. The activity against the neuromuscular blocking action of botulinus neurotoxin type A was examined in mouse phrenic nerve diaphram preparation. The purification procedure of the inactivators was as follows. Tea was extracted with aqueous acetone, and then filtrated and lyophilized. It was also extracted with n-hexane, chloroform, ethyl acetate, n-butylalchol and water, so the activity of the antidote was recognized to be in the n-butylalchol layer (named the thearubigin fraction). A two-step reversed phase HPLC was developed for the thearubigin fraction. Three flavonoids were found to have the major activity. The structural elucidation of the compounds by means of NMR spectrascopy revealed, kaempfenol-3-O-[glc-(6-1)-rha-(3-1)-glc];keampfetrin, kaempferol-3-O-[glc-(6-1)-rha];nicotiflorin and quercetin glycoside.

The mechanism underlying the protective effect of the thearubigin fraction of black tea (Camellia sinensis) extract against the neuromuscular blocking action of botulinum neurotoxins.

The aim of the present study was to elucidate the mechanism of the protective effect of black tea extract, the thearubigin fraction, against the neuromuscular blocking action of botulinum neurotoxin types A, B, and E. The effects of thearubigin fraction extracted from a black tea infusion were examined on the neuromuscular blocking action of botulinum neurotoxin types A, B, and E in mouse phrenic nerve-diaphragm preparations and on the binding of these toxins to rat cerebrocortical synaptosomes. Botulinum neurotoxin type A (1.5 nM), B (6 nM), or E (5 nM) abolished indirect twitches in mouse phrenic nerve-diaphragm preparations within 50, 90, 90 min., respectively. Thearubigin fraction mixed with each toxin blocked the inhibitory effect of the toxins. The specific binding of [125I]botulinum neurotoxin type A, B, or E to rat cerebrocortical synaptosomes was inhibited by mixing iodinated toxin with thearubigin fraction. The elution profile of [125I]botulinum neurotoxin type A, B, or E on Sephadex G-50 column chromatography was different from that of toxin mixed with thearubigin fraction. These findings indicate that thearubigin fraction protects against the neuromuscular blocking action of botulinum neurotoxin types A, B, and E by binding with the toxins.

A mechanism of the thearubigin fraction of black tea (Camellia sinensis) extract protecting against the effect of tetanus toxin.

The aim of the present study was to elucidate the mechanism of the protective effect of black tea extract's thearubigin fraction against the action of tetanus toxin. The effects of thearubigin fraction extracted from a black tea infusion were examined for neuromuscular blocking action on tetanus toxin in mouse phrenic nerve-diaphragm preparations and on the binding of this toxin to the synaptosomal membrane preparations of rat cerebral cortices. The interaction between tetanus toxin and thearubigin fraction was also investigated. Tetanus toxin (4 micrograms/ml) abolished indirect twitches in mouse phrenic nerve-diaphragm preparations within 150 min. Thearubigin fraction mixed with tetanus toxin blocked the inhibitory effect of the toxin. Mixing iodinated toxin with thearubigin fraction inhibited the specific binding of [125I]tetanus toxin to the synaptosomal membrane preparation. The effects of thearubigin fraction were dose-dependent. The elution profile of [125I]tetanus toxin on Sephadex G-50 column chromatography was different from that of toxin mixed with thearubigin fraction. These findings indicate that thearubigin fraction protects against the action of tetanus toxin by binding with the toxin.