セイタイ トウカセイ キンセキガイコウ デ カッセイカ サレル コウシュヨウセイ ブンシ ノ ゴウセイ ト キノウ

One-way geometrical isomerization around a C=C bond of 1,1-diaryl-2-t-butylethene is achieved upon photoirradiation of cyanoaromatics as a light-absorbing sensitizer. In the thermochemical view, there is no difference between both E and Z isomers of the ethene. In view of the structural resemblance of the ethene to some commercially available antitumor pharmaceuticals, the reaction seems to be of interest to examine extensively. Tuning of wavelength of the light would be possible because the reaction is basically a photocatalytic reaction. Key intermediate is a putative distonic cation radical of which is a unique one having a spatially separated radical and ionic centers on the molecular framework. Generation of such an intermediate is due to the presence of a p-electron donating substituent on an aromatic ring and a bulky t-butyl group. Molecular oxygen interacts as superoxide with the C=C bond of the cation radical in a [supra + antara] manner to give a decomposition product, i.e. a benzophenone derivative and pivalaldehyde, via a dioxetane and competitively, one geometrical isomer of the ethene is afforded by splitting oxygen before making two bonds with the ethene cation radical and superoxide

食品中に存在する忌避刺激の受容とその口腔内機能に関する研究

京都大学0048新制・課程博士博士(農学)甲第21310号農博第2295号新制||農||1063(附属図書館)学位論文||H30||N5144(農学部図書室)京都大学大学院農学研究科農学専攻(主査)教授 松村 康生, 教授 丸山 伸之, 教授 谷 史人学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDGA

Innate and acquired tolerance to bitter stimuli in mice.

Tolerance to bitter foods and its potentiation by repetitive exposure are commonly experienced and potentially underlie the consumption of bitter foods, but it remains unknown whether permissive and adaptive responses are general phenomena for bitter-tasting substances or specific to certain substances, and they have not been rigorously studied in mice. Here, we investigated the effects of prolonged exposure to a bitter compound on both recognition and rejection behaviors to the same compound in mice. Paired measurements of rejection (RjT) and apparent recognition (aRcT) thresholds were conducted using brief-access two-bottle choice tests before and after taste aversion conditioning, respectively. First, RjT was much higher than aRcT for the bitter amino acids L-tryptophan and L-isoleucine, which mice taste daily in their food, indicating strong acceptance of those familiar stimuli within the concentration range between RjT and aRcT. Next, we tested five other structurally dissimilar bitter compounds, to which mice were naive at the beginning of experiments: denatonium benzoate, quinine-HCl, caffeine, salicin, and epigallocatechin gallate. RjT was moderately higher than aRcT for all the compounds tested, indicating the presence of innate acceptance to these various, unfamiliar bitter stimuli in mice. Lastly, a 3-week forced exposure increased RjT for all the bitter compounds except salicin, demonstrating that mice acquire tolerance to a broad array of bitter compounds after long-term exposure to them. Although the underlying mechanisms remain to be determined, our studies provide behavioral evidence of innate and acquired tolerance to various bitter stimuli in mice, suggesting its generality among bitterants

Oral Cooling and Carbonation Increase the Perception of Drinking and Thirst Quenching in Thirsty Adults

<div><p>Fluid ingestion is necessary for life, and thirst sensations are a prime motivator to drink. There is evidence of the influence of oropharyngeal stimulation on thirst and water intake in both animals and humans, but how those oral sensory cues impact thirst and ultimately the amount of liquid ingested is not well understood. We investigated which sensory trait(s) of a beverage influence the thirst quenching efficacy of ingested liquids and the perceived amount ingested. We deprived healthy individuals of liquid and food overnight (> 12 hours) to make them thirsty. After asking them to drink a fixed volume (400 mL) of an experimental beverage presenting one or two specific sensory traits, we determined the volume ingested of additional plain, ‘still’, room temperature water to assess their residual thirst and, by extension, the thirst-quenching properties of the experimental beverage. In a second study, participants were asked to drink the experimental beverages from an opaque container through a straw and estimate the volume ingested. We found that among several oro-sensory traits, the perceptions of coldness, induced either by cold water (thermally) or by l-menthol (chemically), and the feeling of oral carbonation, strongly enhance the thirst quenching properties of a beverage in water-deprived humans (additional water intake after the 400 ml experimental beverage was reduced by up to 50%). When blinded to the volume of liquid consumed, individual’s estimation of ingested volume is increased (~22%) by perceived oral cold and carbonation, raising the idea that cold and perhaps CO₂ induced-irritation sensations are included in how we normally encode water in the mouth and how we estimate the quantity of volume swallowed. These findings have implications for addressing inadequate hydration state in populations such as the elderly.</p></div

Estimated volume of beverages ingested when blind to the volume.

<p>Participants were asked to estimate how much they just ingested after drinking an experimental beverage presented in a lidded and opaque cup, through a straw without touching the cup. Legends and dashed lines correspond to actual volumes of the samples. Each condition was tested in triplicate. (A), Three beverages were tested: room temperature water (RT), cold water (CD) and cold carbonated water (CC). Upper panel displays ingested volumes estimated by participants and lower panel shows the time of completion to drink the whole sample. Data are represented as mean +/- SEM * indicates statistical significance at p<0.05 vs RT. (B), Participants did the same task with RT and cold water but at a forced rate (slow (10 bpm) or fast (20 bpm)). Upper panel displays ingested volumes estimated by participants and lower panel shows the time recorded to finish drinking the whole sample. Data are represented as mean +/- SEM. (n = 10 participants).</p

Genetic analysis of chemosensory traits in human twins

We explored genetic influences on the perception of taste and smell stimuli. Adult twins rated the chemosensory aspects of water, sucrose, sodium chloride, citric acid, ethanol, quinine hydrochloride, phenylthiocarbamide (PTC), potassium chloride, calcium chloride, cinnamon, androstenone, Galaxolide™, cilantro, and basil. For most traits, individual differences were stable over time and some traits were heritable (h2 from 0.41 to 0.71). Subjects were genotyped for 44 single nucleotide polymorphisms within and near genes related to taste and smell. The results of these association analyses confirmed previous genotype–phenotype results for PTC, quinine, and androstenone. New associations were detected for ratings of basil and a bitter taste receptor gene, TAS2R60, and between cilantro and variants in three genes (TRPA1, GNAT3, and TAS2R50). The flavor of ethanol was related to variation within an olfactory receptor gene (OR7D4) and a gene encoding a subunit of the epithelial sodium channel (SCNN1D). Our study demonstrates that person-to-person differences in the taste and smell perception of simple foods and drinks are partially accounted for by genetic variation within chemosensory pathways