Ecophysiological consequences of alcoholism on human gut microbiota: implications for ethanol-related pathogenesis of colon cancer.

Chronic consumption of excess ethanol increases the risk of colorectal cancer. The pathogenesis of ethanol-related colorectal cancer (ER-CRC) is thought to be partly mediated by gut microbes. Specifically, bacteria in the colon and rectum convert ethanol to acetaldehyde (AcH), which is carcinogenic. However, the effects of chronic ethanol consumption on the human gut microbiome are poorly understood, and the role of gut microbes in the proposed AcH-mediated pathogenesis of ER-CRC remains to be elaborated. Here we analyse and compare the gut microbiota structures of non-alcoholics and alcoholics. The gut microbiotas of alcoholics were diminished in dominant obligate anaerobes (e.g., Bacteroides and Ruminococcus) and enriched in Streptococcus and other minor species. This alteration might be exacerbated by habitual smoking. These observations could at least partly be explained by the susceptibility of obligate anaerobes to reactive oxygen species, which are increased by chronic exposure of the gut mucosa to ethanol. The AcH productivity from ethanol was much lower in the faeces of alcoholic patients than in faeces of non-alcoholic subjects. The faecal phenotype of the alcoholics could be rationalised based on their gut microbiota structures and the ability of gut bacteria to accumulate AcH from ethanol.

Major Anaerobic Bacteria Responsible for the Production of Carcinogenic Acetaldehyde from Ethanol in the Colon and Rectum.

AIMS: The importance of ethanol oxidation by intestinal aerobes and facultative anaerobes under aerobic conditions in the pathogenesis of ethanol-related colorectal cancer has been proposed. However, the role of obligate anaerobes therein remains to be established, and it is still unclear which bacterial species, if any, are most important in the production and/or elimination of carcinogenic acetaldehyde under such conditions. This study was undertaken to address these issues. METHODS: More than 500 bacterial strains were isolated from the faeces of Japanese alcoholics and phylogenetically characterized, and their aerobic ethanol metabolism was studied in vitro to examine their ability to accumulate acetaldehyde beyond the minimum mutagenic concentration (MMC, 50 µM). RESULTS: Bacterial strains that were considered to potentially accumulate acetaldehyde beyond the MMC under aerobic conditions in the colon and rectum were identified and referred to as 'potential acetaldehyde accumulators' (PAAs). Ruminococcus, an obligate anaerobe, was identified as a genus that includes a large number of PAAs. Other obligate anaerobes were also found to include PAAs. The accumulation of acetaldehyde by PAAs colonizing the colorectal mucosal surface could be described, at least in part, as the response of PAAs to oxidative stress. CONCLUSION: Ethanol oxidation by intestinal obligate anaerobes under aerobic conditions in the colon and rectum could also play an important role in the pathogenesis of ethanol-related colorectal cancer.

Catalytic removal of acetaldehyde in saliva by a Gluconobacter strain.

Acetaldehyde (AA) accumulates in the oral cavity after alcohol intake and is responsible for an increased risk of alcohol-related upper aerodigestive tract (UDAT) cancer among aldehyde dehydrogenase 2-inactive heterozygotes in particular. Thus, the removal of AA from the saliva to a level below its mutagenic concentration (50 µM) after drinking is a potentially straightforward method for reducing the risk of alcohol-related UDAT cancer. Although microbial cells with AA-decomposing activity could potentially serve as a useful agent for the catalytic removal of AA from the saliva without the supplemental addition of cofactors, these cells generally exhibit strong AA-producing activity from ethanol, which is present in excess (50mM) over AA (100 µM) in the saliva after drinking. In this study, we observed that Gluconobacter kondonii (GK) cells efficiently decomposed salivary AA (100-390 µM) without the supplemental addition of cofactors irrespective of the type of alcoholic beverages consumed, even in the presence of an excess of ethanol (63 mM). Hydrogen peroxide, which is carcinogenic in animal experiments, was not produced because of the AA removal. The GK cells incubated at 45 °C and pH 3.5 for 15 h were killed, but they retained 80% of their original AA-decomposing activity. The treated cells were used as nonviable microcapsules that harbor a membrane-bound AA-decomposing activity.

Analysis of N(ε) -ethyllysine in human plasma proteins by gas chromatography-negative ion chemical ionization/mass spectrometry as a biomarker for exposure to acetaldehyde and alcohol.

BACKGROUND: N(ε) -ethyllysine (NEL) is a major stable adduct formed by the reaction of acetaldehyde (AA) with lysine residues in proteins. However, its occurrence and levels in biological specimens and its relationship with AA/alcohol exposure-associated disorders have not been fully elucidated. In this study, we have developed a sensitive and specific method to quantitate NEL levels in human plasma proteins. METHODS: The method consists of (1) purification of the protein fraction of interest by Sephadex G-15 to remove low molecular substances, (2) hydrolysis of proteins with Pronase E in the presence of stable isotope-labeled internal standards, (3) derivatization of amino acids with pentafluorobenzyl (PFB) bromide, and (4) quantification of the PFB derivatives of NEL and l-lysine using gas chromatography-negative ion chemical ionization/mass spectrometry in a selected ion monitoring mode. RESULTS: Using the above method, the NEL levels in human plasma proteins obtained from 10 each of control subjects and alcoholic patients were measured. NEL was detected in all samples analyzed, the average level of NEL in the plasma proteins of alcoholic patients (1.17 ± 0.36 NEL/1,000 l-lysine) being significantly higher than that of control subjects (0.26 ± 0.07 NEL/1,000 l-lysine). CONCLUSIONS: The method could be applied to molecular epidemiological studies to investigate possible associations between the NEL levels in human tissue proteins and human diseases associated with exposure to AA and alcohol.

Enantioselective total synthesis of aperidine.

An efficient total synthesis of aperidine was accomplished using a Rh-catalyzed C-H insertion of a cis-dihydrobenzofuran ring. To circumvent the facile epimerization of the cis-dihydrobenzofuran ring, we designed and prepared the C-H insertion precursor diazoamide by Raines' protocol. Finally, the efficient incorporation of a guanidine group and mild deprotection conditions yielded this labile natural product.

Induction of heme oxygenase-1 by whisky congeners in human endothelial cells.

It is expected that the production of the cytoprotective heme oxygenase-1 (HO-1) protein in endothelial cells would reduce severity of vascular injuries, while phenolic compounds are known to induce HO-1 mRNA and protein in various cells. We investigated the activation of HO-1 by whisky, which contains various phenolic substances. The congeners of whisky stored from 4 to 18 y in oak barrels were shown to induce an increase of HO-1 protein in human umbilical vein endothelial cells, while those of freshly distilled whisky spirit exhibited no activity. To determine the compounds with potent HO-1-inducing activity among the whisky congeners, several chemicals that had been reported to exist in whisky or oak barrels were screened, and coniferyl aldehyde and sinapyl aldehyde showed the activity. Thus, compounds that emerged in whisky during barrel storage induced cytoprotective protein, HO-1, in human endothelial cells.

Inhibitory effects of whisky congeners on IgE-mediated degranulation in rat basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice.

Whisky is matured in oak casks. Many nonvolatile substances (whisky congeners, WC) seep from the oak cask during the maturing process. In this study, three antiallergic agents (syringaldehyde, SA; lyoniresinol, Lyo; and ellagic acid, EA) were isolated from WC. Treatment with SA, Lyo, and EA reduced the elevation of intracellular free Ca(2+) concentration ([Ca(2+)]i) and intracellular ROS production caused by FcepsilonRI activation. The inhibitions of the elevation of [Ca(2+)]i and intracellular ROS production by SA and Lyo were mainly due to the suppression of the NADPH oxidase activity and scavenging of the produced radical, respectively. On the other hand, EA inactivated spleen tyrosine kinase and led to the inhibition of the elevation of [Ca(2+)]i and intracellular ROS production. Furthermore, it was found that WC strongly inhibited IgE binding to the FcepsilonRIalpha chain, whereas SA, Lyo, and EA did not indicate this inhibitory effect. These results suggest that WC inhibits allergic reactions through multiple mechanisms. To disclose the in vivo effects of WC, SA, Lyo, and EA, these compounds were administered to type I allergic model mice, and the passive cutaneous anaphylaxis (PCA) reaction was measured. These compounds remarkably suppressed the PCA reaction. Taken together, these findings suggest that WC seemed to be beneficial to ameliorate allergic reactions.

Polymorphisms of alcohol dehydrogenase-1B and aldehyde dehydrogenase-2 and the blood and salivary ethanol and acetaldehyde concentrations of Japanese alcoholic men.

BACKGROUND: The effects of genetic polymorphism of aldehyde dehydrogenase-2 (ALDH2) on alcohol metabolism are striking in nonalcoholics, and the effects of genetic polymorphism of alcohol dehydrogenase-1B (ADH1B) are modest at most, whereas genetic polymorphisms of both strongly affect the susceptibility to alcoholism and upper aerodigestive tract (UADT) cancer of drinkers. METHODS: We evaluated associations between ADH1B/ADH1C/ALDH2 genotypes and the blood and salivary ethanol and acetaldehyde levels of 168 Japanese alcoholic men who came to our hospital for the first time in the morning and had been drinking until the day before. RESULTS: The ethanol levels in their blood and saliva were similar, but the acetaldehyde levels in their saliva were much higher than in their blood, probably because of acetaldehyde production by oral bacteria. Blood and salivary ethanol and acetaldehyde levels were both significantly higher in the subjects with the less active ADH1B*1/*1 genotype than in the ADH1B*2 carriers, but none of the levels differed according to ALDH2 genotype. Significant linkage disequilibrium was detected between the ADH1B and ADH1C genotypes, but ADH1C genotype did not affect the blood or salivary ethanol or acetaldehyde levels. High blood acetaldehyde levels were found even in the active ALDH2*1/*1 alcoholics, which were comparable with the levels of the inactive heterozygous ALDH2*1/*2 alcoholics with less active ADH1B*1/*1. The slope of the increase in blood acetaldehyde level as the blood ethanol level increased was significantly steeper in alcoholics with inactive heterozygous ALDH2*1/*2 plus ADH1B*2 allele than with any other genotype combinations, but the slopes of the increase in salivary acetaldehyde level as the salivary ethanol level increased did not differ between the groups of subjects with any combinations of ALDH2 and ADH1B genotypes. CONCLUSIONS: The ADH1B/ALDH2 genotype affected the blood and salivary ethanol and acetaldehyde levels of nonabstinent alcoholics in a different manner from nonalcoholics, and clear effects of ADH1B genotype and less clear effects of ALDH2 were observed in the alcoholics. Alterations in alcohol metabolism as a result of alcoholism may modify the gene effects, and these findings provide some clues in regard to associations between the genotypes and the risks of alcoholism and UADT cancer.

Stimulatory effect of N-methyltyramine, a congener of beer, on pancreatic secretion in conscious rats.

BACKGROUND: Alcoholic beverages stimulate gastric acid secretion and increase the appetite. Although ingested ethanol stimulates pancreatic secretion, alcoholic beverages contain several congeners. N-methyltyramine (NMT) was isolated from beer as a factor in stimulating gastric acid secretion. In this study, we examined NMT to determine whether the congener stimulated pancreatic secretion in conscious rats. METHODS: Cannulae were inserted into male Wistar rats to separately drain bile and pancreatic secretions: 2 duodenal cannulae, a gastric cannula, and an external jugular vein cannula. The rats were placed in modified Bollman-type restraint cages. After a 4-day recovery period, experiments were conducted on unanesthetized rats. Different concentrations of NMT (5, 25, and 50 microg/kg) solutions were infused into the stomach. To examine the mechanism, the effects of the proton pump inhibitor, cholecystokinin (CCK-BR) antagonist (YM022), CCK-AR antagonist (CR1505), and atropine were administered prior to the NMT (25 microg/kg) infusion. The effect of intravenous infusion of NMT (7.5 microg/kg) was then determined. Moreover, dispersed acini were prepared, and the effect of different concentrations of NMT on amylase release was determined. RESULTS: Intragastric administration of NMT significantly increased pancreatic exocrine secretion in a dose-dependent manner. Atropine eliminated the stimulatory effect of NMT, but the infusion of the proton pump inhibitor, YM022, and CR1505 did not. Intravenous infusion of NMT did not affect pancreatic secretion, and NMT did not stimulate amylase release in vitro. CONCLUSIONS: N-methyltyramine stimulates pancreatic secretion via the cholinergic gastro-pancreatic reflex. The NMT content in beer was 2 mg/l, so that if a person weighing 60 kg consumes a 750 ml of beer, 25 microg/kg NMT will be ingested. Therefore, the stimulatory effect of beer on pancreatic secretion was produced not only by ethanol but also by the congener, NMT.

Structure-activity relationship study on alpha1 adrenergic receptor antagonists from beer.

Hordatine A and aperidine have been previously isolated from beer as active ingredients, which bind to muscarinic M3 receptor. In addition, these compounds have exhibited antagonist activity against the alpha1A adrenoceptor. Although the relative structures of these two molecules have previously been determined, the absolute stereochemistry was unclear. Hence, to elucidate the absolute stereochemistry of natural hordatine A, we synthesized each enantiomer of hordatine A and aperidine from optically pure dehydrodi-p-coumaric acid. Several additional related compounds were also synthesized for structure-activity relationship studies. Chiral column HPLC analysis demonstrated that the absolute stereochemistry of natural hordatine A is (2S,3S), while based on the isomerization mechanism, the stereochemistry of aperidine is (2R,3S). The alpha1A adrenoceptor binding activity of (2R,3R)-hordatine A is the most potent among the enantiomeric pairs of hordatines and aperidines. Furthermore, the related, synthetic compound, (2R,3R)-methyl benzofurancarboxylate exhibits antagonist activity against the alpha1A adrenoceptor at a lower concentration than that of hordatine A.

Subchronic (13-week) oral toxicity study of dihomo-gamma-linolenic acid (DGLA) oil in rats.

Dihomo-gamma-linolenic acid (DGLA) is one of the essential fatty acids, and has anti-inflammatory and anti-allergic effects. To assess the toxicity of a novel DGLA oil produced by the fungus Mortierella alpina, we examined it in the Ames test and in acute and subchronic oral toxicity tests in rats. In the Ames test, no mutagenicity was found up to 5000 microg/plate. The acute toxicity test revealed no toxicity related to DGLA oil at 10 g/kg. In the subchronic toxicity test, DGLA oil (500, 1000, and 2000 mg/kg) was orally administered. Water and soybean oil (2000 mg/kg) were used for the no-oil control and soybean oil control groups, respectively. There was no death in either sex. Because of administration of large amounts of oil, food consumption was low in the soybean oil control and the three test groups, which appeared to mildly decrease urinary excretion of Na, K, and Cl, as well as total serum protein, albumin, and blood urea nitrogen levels. There were no toxicological changes in body weight, food consumption, ophthalmological examination, urinalysis, hematological examination, blood biochemical examination, necropsy, organ weight, or histopathological examination. These findings show that the no-observed-adverse-effect level of the DGLA oil was 2000 mg/kg.

Isolation and structure of whiskey polyphenols produced by oxidation of oak wood ellagitannins.

Three new phenolic compounds named whiskey tannins A and B and carboxyl ellagic acid were isolated from commercial Japanese whiskey, along with gallic acid, ellagic acid, brevifolin carboxylic acid, three galloyl glucoses, a galloyl ester of phenolic glucoside, 2,3-(S)-hexahydroxydiphenoylglucose, and castacrenin B. Whiskey tannins A and B were oxidation products of a major oak wood ellagitannin, castalagin, in which the pyrogallol ring at the glucose C-1 position of castalagin was oxidized to a cyclopentenone moiety. These tannins originated from ellagitannins contained in the oak wood used for barrel production; however, the original oak wood ellagitannins were not detected in the whiskey. To examine whether the whiskey tannins were produced during the charring process of barrel production, pyrolysis products of castalagin were investigated. Dehydrocastalagin and a new phenolcarboxylic acid trislactone having an isocoumarin structure were isolated, along with castacrenin F and ellagic acid. However, whiskey tannins were not detected in the products.

Salivary acetaldehyde concentration according to alcoholic beverage consumed and aldehyde dehydrogenase-2 genotype.

BACKGROUND: Acetaldehyde is suspected of playing a critical role in cancer development in the upper aerodigestive tract (UADT). The high salivary acetaldehyde levels after alcohol drinking are partly due to acetaldehyde production by oral bacteria. Some alcoholic beverages, especially Calvados and shochu, contain very high levels of acetaldehyde. Inactive heterozygous aldehyde dehydrogenase-2 (ALDH2) increases the risk of UADT cancer in drinkers. METHODS: In a randomized cross-over design study, 19 healthy Japanese volunteers ingested 0.6 g ethanol/kg body weight in the form of 13% ethanol Calvados, 13% ethanol shochu, 13% ethanol red wine, and 5% ethanol beer under the fasting conditions at 3-week intervals. We monitored blood and salivary acetaldehyde concentrations immediately after drinking, and 30, 60, 90, 120, and 180 minutes after completion of drinking. RESULTS: The acetaldehyde concentration of each beverage was: Calvados 0.60 mM (1.86 mM in 40% undiluted solution), shochu 0.60 mM (1.16 mM in 25% undiluted solution), red wine 0.25 mM, and beer 0.14 mM. The salivary acetaldehyde concentration immediately after drinking wine was significantly lower than the other beverages, and it was significantly lower immediately after drinking beer than Calvados. The acetaldehyde concentrations 30 to 180 minutes after drinking were unrelated to the beverage type. Throughout the observation period the salivary acetaldehyde concentrations were much higher than the blood acetaldehyde concentrations in all 12 active ALDH2 homozygotes (24 to 53 microM in saliva vs. 2 to 5 microM in blood) and in all 7 inactive ALDH2 heterozygotes (37 to 76 microM in saliva vs. 12 to 25 microM in blood), and they were 13 to 25 microM higher in the ALDH2 heterozygotes than in the ALDH2 homozygotes after adjusting for age, body weight, sex, smoking and drinking habits, and time since the last toothbrushing. The values after subtracting the blood acetaldehyde concentration from the salivary acetaldehyde concentration were also higher in the ALDH2 heterozygotes than in the ALDH2 homozygotes. CONCLUSIONS: There are differences in exposure of the UADT to high salivary acetaldehyde concentrations according to the type of alcoholic beverage and ALDH2 genotype, and the differences partly explain the differences in the cancer susceptibility of the UADT according to alcoholic beverage and ALDH2 genotype.

Inhibitory effects of whisky congeners on melanogenesis in mouse B16 melanoma cells.

We examined the effect of whisky congeners, substances other than ethanol in whisky, on melanogenesis in mouse B16 melanoma cells. Treatment with whisky congeners significantly blocked melanogenesis. Our results indicate that the inhibitory effects of whisky congeners on melanogenesis is due to direct inhibition of tyrosinase activity and to suppression of tyrosinase protein levels.

Contribution of the alcohol dehydrogenase-1B genotype and oral microorganisms to high salivary acetaldehyde concentrations in Japanese alcoholic men.

The less-active homozygous alcohol dehydrogenase-1B (ADH1B*1/*1) and inactive heterozygous aldehyde dehydrogenase-2 (ALDH2*1/*2) increase the risk of upper aerodigestive tract cancer (UADTC) in Japanese alcoholics. We evaluated associations between ADH1B/ALDH2 genotypes and the blood and salivary ethanol/acetaldehyde levels of 80 Japanese alcoholic men in the morning when they first visited our hospital after drinking the day before. Higher levels of ethanol persisted in the blood for longer periods in ADH1B*1/*1 carriers (n = 25) than in ADH1B*2 allele carriers after adjustment for the amount and time of the preceding alcohol consumption and body weight [median (25th-75th %): 20.5 mM (15.5-52.4) vs. below detection level (

Structural determination of two active compounds that bind to the muscarinic M3 receptor in beer.

BACKGROUND: It is known that beer accelerates gastrointestinal motility in humans. Our previous studies showed that beer congener stimulates gastrointestinal motility by directly stimulating the muscarinic M3 receptor. Further, we isolated 2 active compounds (compounds A and B) from beer by liquid chromatography. The objective of the present study was to identify the 2 active compounds that bind to the muscarinic M3 receptor in beer. METHODS: Structural analyses of the active compounds were performed by fast atom bombardment mass spectra, 1H-nuclear magnetic resonance (NMR), and 13C-NMR spectroscopy. Active compounds were chemically synthesized from p-coumaric acid and agmatine as starting materials. Binding activity to the muscarinic M3 receptor was used to confirm the activity of the synthetic compounds. RESULTS: It was identified that 2 active compounds had the same structural characteristics: stereoisomers (cis-isomer and trans-isomer), molecular weight=550 and molecular formula=C28H38N8O4. Trans-isomer (compound B) was identified as the known substance hordatine A, a kind of phytoalexin in barley, and cis-isomer (compound A) was found to be a novel compound (tentatively referred to as aperidine). Both naturally present and chemically synthesized aperidine (compound A) and hordatine A (compound B) were demonstrated to have potent binding activities to the muscarinic M3 receptor. CONCLUSIONS: The 2 active compounds isolated from beer, namely aperidine (compound A) and hordatine A (compound B), have structurally and functionally been identified as active entities of binding to the muscarinic M3 receptor.

Effect of xylooligosaccharide intake on severe constipation in pregnant women.

Xylooligosaccharides (XOS) are mainly composed of two or three xylose units with beta-1,4 linkages. They are obtained by hemicellulose hydrolysis, which is relatively abundant in the cell walls of grains. XOS increases the number of intestinal Bifidobacterium in humans, and maintains the fecal water content within the normal range. To examine the effect of XOS intake on severe constipation in pregnancy, which is predominant in the third trimester, thirty constipated pregnant women were treated with 4.2 g XOS daily for 4 wk. During the study, the clinical efficacy was assessed using a daily diary. The subjects indicated the number of stools and the clinical symptom scores. Twenty-nine subjects completed the study. The mean number of stools was 1.1 +/- 0.4 in the pre-treatment week, and increased in weeks 1-4 of XOS administration to 5.3 +/- 2.1, 5.9 +/- 2.5, 6.2 +/- 2.2 and 6.7 +/- 1.9, respectively. At the end of the study, 27 subjects could defecate spontaneously. The occurrence of very loose or very hard stools decreased and the stool consistency normalized. The stool color changed from dark to yellowish brown. No side effects were observed. XOS intake was highly effective for the reduction of severe constipation in pregnant women without adverse effects.

Isolation of stimulants of gastrointestinal motility in beer.

BACKGROUND: Among various alcoholic beverages, it has reported that beer has a potent activity to stimulate gastric emptying. Our previous studies showed that beer congener stimulated gastrointestinal motility by directly stimulating muscarinic M3 receptor, present in smooth muscles of the gastrointestinal tract. However, active components that account for the action have yet to be identified. We attempted to isolate the stimulant(s) of gastrointestinal motility in beer. METHODS: Beer congener was prepared from beer and used to separate and purify active components by a series of liquid chromatography using affinity to muscarinic M3 receptor as an index. Gastrointestinal motility-stimulating activity was evaluated using a test for activity that causes contraction of longitudinal muscles in guinea pig ileum and a test for gastric emptying activity in mice. RESULTS: The active components (compounds A and B) were purified and isolated from beer by four liquid chromatography steps. The IC50 values of two active isolates to muscarinic M3 receptor were 0.65 x 10 g/ml and 2.30 x 10 g/ml, respectively. The concentrations of compounds A and B contained in beer were sufficient to explain most of the muscarinic M3 receptor binding activity of beer. The active fraction that contained both compounds A and B (which was 10 times as active as beer congener in muscarinic M3 receptor binding activity) dose-dependently contracted the longitudinal muscles of guinea pig ileum with an activity that was 20 times as potent as that of beer congener. The same active fraction significantly stimulated gastric emptying in mice with an activity 20 times as potent as that of beer congener. CONCLUSIONS: Two active components (compounds A and B) were isolated as gastrointestinal motility stimulants (muscarinic M3 agonists) in beer. These results suggest that the two isolated active components are the active entities of the gastrointestinal motility-stimulating effect of beer.

Effects of fusel oil on animal hangover models.

BACKGROUND: Fusel oil has been reported to have undesirable side effects such as hangover. However, the relationship between fusel oil and hangover has been investigated insufficiently. In this study, we investigated the effects of fusel oil and their ingredients contained in alcoholic beverages by using animal hangover models. METHODS: Ethanol and fusel oil were simultaneously administered to Suncus murinus, and emetic responses were observed for 60 min. Ethanol and fusel oil were simultaneously administered to mice immediately after intake of saccharin solution; on the next day, the mouse's saccharin solution intake was measured. RESULTS: The volatile fraction (fusel oil) of whisky had no remarkable effect on ethanol-induced emetic responses in suncus. Whisky had the most suppressive effect on ethanol-induced conditioned taste aversion in mice among the various alcoholic beverages tested. The volatile fraction (fusel oil) of whisky suppressed the ethanol-induced conditioned taste aversion. In contrast, the nonvolatile fraction of whisky had no effect. The administration of isoamyl alcohol (5 mg/kg) and isoamyl acetate (10 and 40 microg/kg), ingredients of fusel oil, significantly suppressed the ethanol-induced conditioned taste aversion. CONCLUSIONS: The fusel oil in whisky had no effect on the ethanol-induced emetic response, but it suppressed taste-aversion behavior in animal models of hangover symptoms. These results suggest that the fusel oil in whisky alleviates hangover, contrary to the common belief.

Influence of moderate drinking on purine and carbohydrate metabolism.

BACKGROUND: We examined the influences of a moderate intake level of three types of alcoholic beverages--beer, whisky, and Shochu (Japanese distilled liquor)--on purine and carbohydrate metabolism and excretion in healthy male volunteers, concerning (1) the extent of contribution of purine bodies contained in beer to uric acid metabolism and (2) a comparison between two types of distilled spirits with (whisky) and without (Shochu) aging in oak wood barrel storage. METHODS: Three sets of studies were conducted in which 10 to 13 healthy adult men were instructed to drink three types of alcoholic beverages at a slightly higher level (0.8 ml of ethanol equivalent/kg body weight) than moderate drinking (approximately 30.4 ml or less for men). A low purine beer was test-manufactured by treating nucleosides that were contained in wort and remained in beer with purine nucleoside phosphorylase derived from Ochrobacterium anthropi, thereby converting them into corresponding purine bases that were easily assimilated by beer yeast. RESULTS: Although beer intake enhanced the level of serum uric acid by 13.6%, blood glucose by 26.7%, and insulin level by 5.1-fold, drinking a moderate level of distilled liquor (whisky, Shochu) did not increase the serum uric acid level or the other two parameters. The serum uric acid level observed after drinking beer with a purine body concentration reduced by 28% (68% in nucleosides and purine bases) was almost identical to the level observed after drinking regular beer. Whisky has been found to have a property that decreases the serum uric acid level. Excretion of uric acid from blood is increased by 27% after drinking whisky. CONCLUSIONS: Moderate drinking of distilled liquors did not enhance serum uric acid level, blood glucose, or insulin level in healthy male subjects. Increased serum uric acid after beer intake could not be explained mostly with their purine body congeners. Whisky showed the eliminative property in serum uric acid through excretion of it from blood to urine. At a moderate drinking level, beer and whisky have different effects on purine metabolism or excretion.