江頭 祐嘉合

The effects of dietary corn bran hemicellulose (CBH) and neomycin (Neo) on hepatic caspase-3 activity and glycoprotein concentration were investigated to explore the possible mechanism of the alleviative action of dietary CBH and Neo oil the development of D-galactosamine (GaIN)-hepatitis. Rats were fed a diet containing 50% CBH with or without neomycin (Neo) for 7 or 14 d. On the last day of feeding. the rats were treated with GaIN (400 mg/kg body weight, i.p.), and their plasma transaminase activities, hepatic glycoprotein concentrations and hepatic caspase-3 activities were determined 6 or 24 h later. Although the elevations of plasma transaminase activities were suppressed by CBH or Neo 24 h after GalN-treatment, the activities were not affected by CBH or Neo at an early stage (6 h) of GaIN action. At 6 h. hepatic caspase-3 activity was elevated by CBH diet alone as high as that of the GalN-injected control-diet group, and the activity was not elevated further by GaIN. At the same time. both GalN-treatment and CBH feeding reduced the hepatic glycoprotein (MA 64.000-74.000) concentration, but Neo did not affect the caspase activity or the glycoprotein concentration. These results Suggest that dietary CBH elevates hepatic caspase-3 activity and reduces hepatic glycoprotein concentration, and may imply that CBH would suppress GalN-hepatitis not at the early- or middle-step of apoptosis but at the late-step of apoptosis or necrosis, although the relation between these phenomena and the alleviative effects of CBH and Neo on GalN-induced hepatitis is yet to be clarified.

Acetaminophen (APAP) is mostly eliminated at a therapeutic dose through glucuronidation and sulfatation, while a small fraction is oxidized by cytochromes P450 (CYP) into N-acetyl-P-benzoquinone-imine (NAPQI). NAPQI, a highly reactive metabolite of APAP is then conjugated with glutathione (GSH) and the product can be excreted into the urine. At an APAP overdose, glucuronidation and the sulfatation pathway are saturated and the production of NAPQI increases, resulting in a rapid depletion of the GSH concentration. Subsequently, NAPQI reacts with cellular macromolecules causing hepatic injury. Based on our previous studies, it was shown that APAP-induced hepatotoxity in rats was protected by butylated hydroxyanisol (BHA) and butylated hydroxytoluene (BHT), but the in protection mechanisms could be somewhat different. In this study, we have confirmed the protective effects of BHA and BHT against APAP-induced liver injury using histopathological and morphological observations of the rat liver. Rats were given BHA or BHT (0.5% each) as the ingredient added to their diets for 7 days, then APAP (500 mg / kg IP) was injected. On the other hand, BHA has almost no effects on the induction of hepatic heat shock proteins, but BHT depressed them in the rats administered APAP during 0-24 h. This means that the differences in the inhibition mechanisms of BHA and BHT are the induction of chaperones or other protein(s) and increasing the hepatic GSH accumulation or decreasing the degenerated protein in the hepatic cells by the putative protein conjugated with NAPQI in APAP-induced liver injury. © 2006, Japan Oil Chemists' Society. All rights reserved.

The effects of dietary administration of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on acetaminophen (APAP)-induced hepatic metabolism in rats were examined. The administration method involves providing the rats with 0.5% each of BHA and BHT separately added to their diets for 7 days. Based on the results of the plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities for dietary administration, BHA and BHT in the diets fully prevented APAP-induced hepatotoxicity (500 mg / kg IP). By adding BHA and BHT to feedstuffs, hepatic UDP-glucuronosyltransferase (UDP-GTase) remained activated in the rats. The excreted amount of APAP-glucuronide increased and the residual APAP declined in the urine of the rats. After APAP administration in BHA or BHT pretreated rats, the excretion in plasma reached the largest amount for APAP-glucuronide at 2-4 h and APAP-sulfate at 6 h. It was clear that BHT excelled over BHA in playing the role of promoting hepatic metabolism. Data thus obtained showed the proposed different metabolisms in APAP-induced hepatotoxicity between BHA and BHT. © 2006, Japan Oil Chemists' Society. All rights reserved.

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidney alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

In the present study, the production of a novel feruloyl esterase (FAE) from a typical human intestinal bacterium Lactobacillus acidophilus using various carbon sources was investigated. The results showed that FAE activity was strongly induced by hemicellulosic substances, with the highest activity detected when de-starched wheat bran (DSWB) was used as a carbon source. Moreover, the production was stimulated by the monosaccharides xylose and arabinose, suggesting its particular secretion mechanism. With increasing levels of free ferulic acid (FA) added, the production of FAE increased, reached a peak and declined. Further, on addition of either xylanase or a-L-arabinofuranosidase, the amount of FA released from DSWB by the purified FAE from L. acidophilus increased from 0 to 12.4 nmol and 3.64 nmol, respectively. When the three enzymes existed together, 15.7 nmol of FA was detected. These results indicated that xylanase is predominant and arabinofuranosidase subordinate in their synergistic effect on FA release by FAE.

Objective: It is well known that the indigestible oligo- and polysaccharides including dietary fiber are important food components and that they have many physiologic functions. This study examined the effect of water-soluble corn bran hemicellulose (CBH) on the development of D-galactosamine (GalN) hepatitis in rats to obtain some knowledge about new functions of dietary fiber. Methods: Male Wistar rats were fed diets containing 5% CBH for various days (I to 14 d). On the final day of feeding rats were treated with GalN (400 mg/kg), and their plasma transaminase (aspartate and alanine aminotransferases) activity (6 or 24 h later) and liver glutathione concentration (6 h later) were determined. Results: Ingested CBH suppressed the increase in plasma aspartate and alanine aminotransferase activities 24 It after GalN treatment. Such suppressive effect was observed only 7 d after CBH ingestion and not after I or 3 d. In the early phase of the liver injury, at 6 h after GalN treatment, the liver glutathione concentration in the CBH group was significantly higher than that in the control group, and the concentration in the CBH group after GalN injection was almost the same as that in the control group without GalN treatment. Conclusion: Results suggest that dietary CBH suppresses the development of hepatic injury by GalN in rats and that this phenomenon is partly attributable to the increase in hepatic glutathione concentration by CBH. (c) 2005 Elsevier Inc. All rights reserved.

Phenolic acids (PAs) have been shown to be beneficial to human health and are found most abundantly in corn bran (similar to 4 %, w/w), one of the main dietary fibers. This study therefore evaluated the bioavailabilities of phenolic antioxidants ferulic acid (FA) and p-coumaric acid (PCA) in refined corn bran (RCB) by determining their recovery in the plasma, urine, and feces of rats fed a single meal of a RCB diet containing 5 % RCB or adapted to the RCB diet for 10 days. In both studies, 0.4-0.5 % of ingested FA and 1.2-2.3 % of ingested PCA were recovered in rat urine. By contrast, similar to 81 % of FA and similar to 64 % of PCA ingested with the single meal were excreted through the rat feces within 3 days after the ingestion. On the other hand, after rats were fed the RCB diet, total FA (all forms of FA) was recovered in plasma at a concentration of 35.0 +/- 2.0 mu g/L, total FA and total PCA were excreted through urine at levels of 155.4 +/- 5.8 and 50.9 +/- 6.6 mu g/day, respectively. These parameters showed no significant change (P = 0.93, 0.09, and 0.66, respectively) after rats were fed the RCB diet continuously for up to 10 days. These results suggest that the PAs in RCB are bioavailable in rats. Their bioavailabilities, however, are relatively low compared with their high content in RCB and not improved by the adaptation for 10 days to the enriched RCB diet. Additionally, comparison with the results of other studies revealed that high contents of FA and, especially, diferulic acids in cereal bran, which act as cross-links between bran cell wall polysaccharides, may not improve but, rather, limit the bioavailabilities of PAs in vivo.

この研究はトウモロコシ外皮ヘミセルロースから酵素処理によって得られた分子量286-930にあるオリゴ糖によるD-galactosamine肝障害の抑制メカニズムを解明するために行われた。4週齢の雄Wistarラットにこのオリゴ糖を7日間投与した。7日目にD-galactosamine肝障害を起こしたラットについて,このオリゴ糖が血中のエンドトキシン,サイトカイン含量および肝臓のアポトーシスに及ぼす影響を調べた。その結果,このオリゴ糖の添加により,明らかに血中エンドトキシンおよびTumorNecrosisFactor(TNF-α)レベルの上昇が阻止された。しかし,血中のInterferon-γ(IFN-γ)含量および肝臓DNAの断片化に対してこのオリゴ糖はほとんど影響を与えないことが示唆された。従って,トウモロコシ外皮ヘミセルロースから酵素処理によって得られたオリゴ糖によるD-galactosamine肝障害への抑制作用はこのオリゴ糖の血中エンドトキシンおよびTNF-α レベルの上昇に対する抑制作用によるものであると考えられた。

Many studies have been reported that dietary wheat bran, cellulose, resistant starch and inulin suppressed experimental colon tumors or cancer in rats. Dietary fiber reduces contact between the intestinal contents and mucosa, and leads to production of short-chain fatty acids, acetate, propionate, and butyrate, which reduce pH and the conversion of primary to secondary bile acids. Butyrate is the major source of energy for the distal colon and it reduces cell proliferation and induces apoptosis, factors that are associated with inhibition of the transformation of the colonic epithelium to carcinoma. On the other hand, dietary fiber is thought to protect against colorectal cancer in human but this view has been challenged by recent cohort studies that showed no protective effect.

We assessed the protective effect of the dietary antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) against acetaminophen (APAP)-induced hepatotoxicity. After giving diets containing BHA (0.5%), BHT (0.5%) to male Wistar rats for 7 days, they were fasted for 16 h and then intraperitoneally injected with APAP (0.5g/kg). The severity of the hepatic injury was inferred from the plasma alanine aminotransferase and aspartate aminotransaferase levels 24 h later. The results indicated that BHA and BHT significantly protected the rats against APAP hepatotoxicity. Upon investigating the mechanism of the protective action of BHA and BHT, the hepatic glutathione (GSH) levels decreased to the same degree in the APAP, BHA + APAP, and BHT + APAP groups 2 h after the injection of APAP, while the GSH levels started to recover in all groups at 6 h, but increasing faster in the BHA + APAP and BHT + APAP groups than in the APAP group. As compared with the control group, the hepatic cytochrome P450 (CYP) 2E1 levels tended to be about 20% higher in the BHA + APAP group from 2 to 24 h, and about 30% higher in the BHT + APAP group only at 24 h. These results suggest that the protection against APAP-induced hepatotoxicity provided by BHA and BHT is partly due to rapid recovery of the hepatic glutathione levels but does not involve changes in the CYP2E1 levels.<br>

We examined the effects of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on acetaminophen - induced hepatotoxicity using two different administration methods i.e, feeding rats with BAH- and BHT- added diets, and by direct oral administration. In the former case, BHA and BHT (0.5% each) were separately added to experimental diets which were given to rats for 7 days, and then after a 16 h - fast, APAP (500mg/ kg) was intraperitneally given. The oral administration of BHA or BHT (125 mg/kg body weight) was carried out 2 h before the APAP treatment. The elevation of the plasma AST and ALT activities as an index of liver injury was significantly suppressed in the BHA- and BHT- fed groups at 24 h after the APAP treatment and significantly lower levels in the BHA oral pretreatment group were seen when compared with those in the APAP group. On the other hand, the BHT oral pretreatment group showed rather high AST and ALT activities. The restraint function was clarified when BHA and BHT were fed, and also when BHA was orally administered, although a similar function was not observed in case of the oral administration of BHT. The inductions of Hsp25 and Hsp70i by APAP were not depressed by the BHA administration, but were suppressed by the BHT except in the case of Hsp70i in the group orally given BHT. These results suggest that BHT blocks NAPQI to covalently bind to the cellular macromolecules, although BHA does not. © 2005, Japan Oil Chemists' Society. All rights reserved.

The purpose of the present study was to investigate the preventive effect of different Molecular Weight (MW) fragments from dietary fiber Corn Bran Hemicellulose (CBH) on hepatitis induced by D-galactosamine in rats in relation to their degradation and fermentation in gastrointestinal tract. Rats fed the diets supplemented with the fragments with or without neomycin sulfate in experiment 1 and the diets supplemented with Short Chain Fatty Acids (SCFAs) in experiment 2 were administered with D-galactosamine intraperitoneally. The serum transaminase activities, cecal and fecal total and reducing sugar content, cecal SCFAs were analysed. Among the fragments tested, the oligosaccharide fragments with MW ranging from 285.7 to 930.1 significantly suppressed the enhancement of serum transaminase levels caused by D-galactosamine. The ingested oligosaccharide fragments produced striking amount of SCFAs in cecum particularly propionate formation. However, SCFAs tested in experiment 2 could not suppress the elevation of serum transaminase levels by D-galactosamine. The present study demonstrated that the oligosaccharide fragments were effective in preventing D-galactosamine hepatitis and the effect might not be mediated by the action of SCFAs. © 2005 Asian Network for Scientific Information.

Ferulic acid (FA) is one of the most abundant phenolic antioxidants in the human diet. Many studies have documented its beneficial properties. It is therefore essential to understand the absorption and metabolism of FA in detail. The purpose of this study was to confirm the hypothesis that FA is absorbed in rat stomach and metabolized mainly in the liver. We determined the recovery of FA and its metabolites (FA sulfate/glucuronicles) in rat gastric contents, gastric mucosa, portal vein plasma, celiac arterial plasma, bile, and urine after 2.25 mumol FA was administered in 0.5 mL physiological saline and incubated for 25 min in situ in the stomach of rats. Within 25 min, 74 +/- 11% of the administered FA disappeared from the stomach; later, FA was recovered in both free and conjugated forms in plasma, bile, and urine. On the other hand, only free FA was detected in the gastric contents and mucosa; it was also detected in the portal vein plasma as 49 +/- 5% of the total FA (all forms of FA). However, the proportion of free FA in the celiac arterial plasma, bile, and urine decreased to 5-8%. These results indicate that FA can be quickly absorbed from the rat stomach, and then is likely metabolized mainly in the liver. Such novel information would be helpful in the use of FA as a nutrient supplement. For example, oral administration of FA in capsule form or in a form bonded with sugar esters may provide a more appropriate concentration of FA in the circulation, which may improve its proposed efficacy in preventing chronic disease.

Hepatic alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD; formerly termed picolinic carboxylase) [EC4.1.1.45] plays a key role in regulating NAD biosynthesis and the generation of quinolinate (quinolinic acid) from tryptophan. Quinolinate is a potent endogenous excitotoxin of neuronal cells. We previously reported that ingestion of fatty acids by rats leads to a decrease in their hepatic ACMSD activity. However, the mechanism of this phenomenon is not clarified. We previously purified ACMSD and cloned cDNA encoding rat ACMSD. Therefore, in this study, we examined the differential effect of fatty acids on ACMSD mRNA expression by Northern blot. Moreover, we measured quinolinic acid concentration in rats fed on fatty acid. When diets containing 2% level of fatty acid were given to male Sprague-Dawley rats (4 weeks old) for 8 days, long-chain saturated fatty acids and oleic acid did not affect ACMSD mRNA expression in the liver. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) strongly suppressed the liver ACMSD mRNA expression. In rats fed with high linoleic acid diet for 8 days, serum quinolinic acid was significantly increased as compared with the rats fed on a fatty acid-free diet under the condition of the approximately same calorie ingestion. These results suggest that the transcription level of ACMSD is modulated by polyunsaturated fatty acids, and suppressive potency of ACMSD mRNA is n-3 fatty acid family&gt;linoleic acid (n-6 fatty acid)&gt;saturated fatty acid. Moreover, this study provides the information that a high polyunsaturated fatty acid diet affects the production of quinolinic acid in serum by suppressing the ACMSD activity. (C) 2004 Elsevier B.V All rights reserved.

<title>ABSTRACT</title> Dietary ferulic acid (FA), a significant antioxidant substance, is currently the subject of extensive research. FA in cereals exists mainly as feruloylated sugar ester. To release FA from food matrices, it is necessary to cleave ester cross-linking by feruloyl esterase (FAE) (hydroxycinnamoyl esterase; EC 3.1.1.73). In the present study, the FAE from a human typical intestinal bacterium, <italic>Lactobacillus acidophilus</italic> , was isolated, purified, and characterized for the first time. The enzyme was purified in successive steps including hydrophobic interaction chromatography and anion-exchange chromatography. The purified FAE appeared as a single band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular mass of 36 kDa. It has optimum pH and temperature characteristics (5.6 and 37°C, respectively). The metal ions Cu ²⁺ and Fe ³⁺ (at a concentration of 5 mmol liter ⁻¹ ) inhibited FAE activity by 97.25 and 94.80%, respectively. Under optimum pH and temperature with 5- <italic>O</italic> -feruloyl- <sc>l</sc> -arabinofuranose (FAA) as a substrate, the enzyme exhibited a <italic>K</italic> <italic> _m </italic> of 0.0953 mmol liter ⁻¹ and a <italic>V</italic> _max of 86.27 mmol liter ⁻¹ min ⁻¹ mg ⁻¹ of protein. Furthermore, the N-terminal amino acid sequence of the purified FAE was found to be A R V E K P R K V I L V G D G A V G S T. The FAE released FA from <italic>O</italic> -(5- <italic>O</italic> -feruloyl-α- <sc>l</sc> -arabinofuranosyl)-(1→3)- <italic>O</italic> -β- <sc>d</sc> -xylopyranosyl-(1→4)- <sc>d</sc> -xylopyranose (FAXX) and FAA obtained from refined corn bran. Moreover, it released two times more FA from FAXX in the presence of added xylanase.

特定保健用食品素材として広く使用されているラクチュロース、フラクドオリゴ糖、イソマルトオリゴ糖および健康食品素材であるアガリクスが糖尿病および高コレステロール血症時に及ぼす影響を、血中成分値を指標に検討した。1.糖尿病時の健康食品素材の影響 ストレプトゾトシンをラットの腹腔内に注射し、糖尿病モデルを作成し、その後10日間特定保健用食品素材および健康食品素材を自由に摂取させた。その結果、試験飼料投与による体重増加量、屠体重に対する肝臓重量比に有意な差は認められなかった。血清コレステロール値は、イソマルトオリゴ糖はプラクトオリゴ糖群より有意に低い値を示した。血糖値、コレステロール値、A/G比、クレアチニン濃度は、各群間で有意な差は認められずこれらの食品素材は、この実験条件下で検討した項目に関しては糖尿病を増悪させることはなかった。2.高コレステロール血症時の健康食品素材の影響 ラットに高コレステロール食を投与しコレステロール値を上昇させ、その後10日間特定保健用食品素材と健康食品素材を自由に摂取させた。そして高コレステロール血症を増悪させるか否か検討した。その結果、アガリクス群は対照群に比し、有意に血清トリグリセリドを減少させた。この実験条件下で検討した項目に関してはこれらの食品素材は、高コレステロール血症を増悪させることはなかった。

Quinolinate (quinolinic acid) is a potent endogenous excitotoxin of neuronal cells. Elevation of quinolinate levels in the brain has been implicated in the pathogenesis of various neurodegenerative disorders, the so-called "quinolinate hypothesis." Quinolinate is non-enzymatically derived from 2-amino-3-carboxymuconate-6-semialdehyde (ACMS). 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase (ACMSD) is the only known enzyme which can process ACMS to a benign catabolite and thus prevent the accumulation of quinolinate from ACMS. ACMSD seems to be regulated by nutritional and hormonal signals, but its molecular mechanism has, to date, been largely unknown. Utilizing partial amino acid sequences obtained from highly purified porcine kidney ACMSD, a cDNA encoding human ACMSD was cloned and characterized. The cDNA encodes a unique open reading frame of 336 amino acids and displays little homology to any known enzymes or motifs in mammalian databases, suggesting that ACMSD may contain a new kind of protein fold. Real-time PCR-based quantification of ACMSD revealed very low but significant levels of the expression in the brain. Brain ACMSD messages was down- and up-regulated in response to low protein diet and streptozocin-induced diabetes, respectively. Expression of QPRT, another enzyme which catabolizes quinolinate, was also found in the brain. This suggests that a pathway does exist by which the levels of quinolinate in the brain are regulated. In. this report, we address the molecular basis underlying quinolinate metabolism and the regulation of ACMSD expression.

Quinolinate (quinolinic acid) is a potent endogenous excitotoxin of neuronal cells. Elevation of quinolinate levels in the brain has been implicated in the pathogenesis of various neurodegenerative disorders, the so-called "quinolinate hypothesis." Quinolinate is nonenzymatically derived from alpha-amino-beta-carboxymuconate-epsilon-semialdehyde (ACMS). alpha-Amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) is the only known enzyme that can process ACMS to a benign catabolite and thus prevent the accumulation of quinolinate from ACMS. ACMSD seems to be regulated by nutritional and hormonal signals, but its molecular mechanism has, to date, been largely unknown. Utilizing partial amino acid sequences obtained from highly purified porcine kidney ACMSD, a cDNA encoding human ACMSD was cloned and characterized. The cDNA encodes a unique open reading frame of 336 amino acids and displays little homology to any known enzymes or motifs in mammalian databases, suggesting that ACMSD may contain a new kind of protein fold. Real-time PCR-based quantification of ACMSD revealed very low but significant levels of the expression in the brain. Brain ACMSD messages were down- and up-regulated in response to low protein diet and streptozocin-induced diabetes, respectively. The enzyme activities measured from partially purified brains were closely correlated with the changes in the message levels. Expression of quinolinate phosphoribosyltransferase (QPRT), another enzyme that catabolizes quinolinate, was also found in the brain. This suggests that a pathway does exist by which the levels of quinolinate in the brain are regulated. In this report, we address the molecular basis underlying quirtolinate metabolism and the regulation of ACMSD expression.

In the tryptophan-niacin conversion, 2-amino-3-carboxymuconate-6-semiardehyde decarboxylase ACMSD; formerly termed picolinic carboxylase) is an important enzyme regulating the generation of quinolinate. In a series of experiments, we investigated alterations of ACMSD expression in rats by feeding a high protein diet and by inducing diabetes with streptozotocin (STZ). Male Sprague-Dawley rats (5-wk-old) were fed a diet containing 40% casein for 11 d, and hepatic ACMSD activity and mRNA expression were determined at intervals. The enzyme activity had increased at d 2, and it continued to increase through d 11. ACMSD mRNA expression had increased at d 1 and the elevated levels were maintained through d 11. Shifting from the 40% casein diet to a 20% casein diet restored hepatic ACMSD activity and mRNA expression to normal levels within 5 d and 2 cl, respectively. In another series of experiments, male Wistar rats were injected with STZ (50 mg/kg) and the time-course (d 0, 1, 2, 4, 8 and 14) of the change in hepatic ACMSD activity and mRNA expression were examined. The activity increased dramatically after d 4, while mRNA expression was significantly elevated at d 2, followed by slight increases through d 14. Insulin administration (2 U/12 h) reduced the elevated ACMSD activity and fully suppressed the elevated ACMSD mRNA expression due to STZ injection. These results indicated that the fluctuation of hepatic ACMSD mRNA expression was followed by that of ACMSD activity.

2-Amino-3-carboxymuconate-6-semialdehyde decarboxylase (ACMSD; EC 4.1.1.45) is one of the important enzymes regulating tryptophan-niacin metabolism. In the present study, we purified the enzyme from rat liver and kidney, and cloned the cDNA encoding rat ACMSD. The molecular masses of rat ACMSDs purified from the liver and kidney were both estimated to be 39 kDa by SDS/PAGE. Analysis of N-terminal amino acid sequences showed that these two ACMSDs share the same sequence. An expressed sequence tag (EST) of the mouse cited from the DNA database was found to be identical with thus N-terminal sequence. Reverse transcription-PCR (RT-PCR) was performed using synthetic oligonucleotide primers having the partial sequences of the EST, and then cDNAs encoding rat ACMSDs were isolated by using subsequent 3'-rapid amplification of cDNA ends and RT-PCR methods. ACMSD cDNAs isolated from liver and kidney were shown to be identical, consisting of a 1008 by open reading frame (ORF) encoding 336 amino acid residues with a molecular mass of 38091 Da. The rat ACMSD ORF was inserted into a mammalian expression vector, before transfection into human hepatoma HepG2 cells. The transfected cells expressed ACMSD activity, whereas the enzyme activity was not detected in uninfected parental HepG2 cells. The distribution of ACMSD mRNA expression in various tissues was investigated in the rat by RT-PCR. ACMSD was expressed in the liver and kidney, but not in the other principal organs examined.

The protective effects of various kinds of dietary amino acids against the hepatotoxic action of D-galactosamine (GalN) were examined. Male Wistar rats fed with 20% casein diets containing 10% or 5% amino acid for one week were injected with GalN (800 mg/kg body weight), and the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) activities, the hepatic glycogen concentration, and the serum glucose-level were examined 20 hours after the injection. In the groups with the 10% amino acid diets, activities of AST, ALT, and LDH in serum of 10% L-glutamine (Gln), 10% L-asparagine (Asn), and 10% L-serine (Ser) groups were significantly lower than those of the control group, and in the groups with the 5% amino acid diets, those activities of 5% L-histidine (His), 5% L-tyrosine (Tyr), 5% L-lysine (Lys), and 5% L-glycine (Gly) groups were also lower than those of the control group. The concentration of liver glycogen of 10% Gln-, 10% Asn-, and 10% Sergroups and those levels of 5% His-, 5% Tyr-, 5% Lys-, and 5% Gly-groups were also significantly higher than that of the control group. As a result, it was found that some kinds of dietary amino acid such as L-Ser, L-Asn, L-His, L-Lys, L-Tyr, and L-Gly, in addition to L-Gln were effective to protect the rats from GalN-induced injury.

alpha-Amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) [EC 4.1.1.45] is a key enzyme of niacin synthesis from tryptophan. In this study, we examined whether dietary linoleic acid alters the protein expression of ACMSD in rat liver. Antibody against rat liver ACMSD was prepared by injecting mice with the purified enzyme. With the use of this polyclonal antibody and analysis by two-dimensional electrophoresis, we studied the mechanism by which the level of liver ACMSD activity was varied in rats fed a linoleic acid diet. In the rats fed a dietary linoleic acid (L), ACMSD protein levels in the liver were strongly suppressed as compared with the rats fed a fat-free diet (FF). These results suggest that the expression level of ACMSD might be modulated by linoleic acid or their metabolites.

Ferulic acid esterase activity arose in the ceca of rats that were fed on acid hydrolysate of refined corn bran. The main component of this hydrolysate was soluble ferulic acid arabinoxylan ester. In order to determine the relationship between the ferulic acid esterase activity and intestinal bacteria, the ferulic acid esterase activities from the four kinds of typical bacteria in the intestine were measured. Ferulic acid arabinose ester (LMW) and ferulic acid arabinoxylan ester (HMW) were used as substrates. The enzyme from Lactobacillus acidophilus exhibited the highest activity when LMW was used as a substrate. However, when HMW was used, all enzymes from these bacteria exhibited trace activities. At the same time, Bifidobacterium bifidum showed high xylanase and arabinofuranosidase activities. It was suggested that the xylanase and the arabinofuranosidase from bacteria such as B. bifidum attacked HMW and degraded it to lower molecules at first. The ferulic acid esterase from bacteria such as L. acidophilus might then act to release ferulic acid in the cecum.

Antioxidant activity of ferulic acid beta-glucuronide, which is prepared from the plasma of feruloyl arabinose fed rats, in the CuSO4- induced LDL autoxidation system was studied. It has been found that absorbed ferulic acid occurred as the beta-glucuronide and that the antioxidant activity of ferulic acid beta-glucuronide, which has not only the hydrophobic ferulic acid moiety but also a hydrophilic sugar moiety, is stronger than ferulic acrid in the LDL oxidation system.

Enzymatic activities in cecal contents were studied on rats fed on high cholesterol diets with ferulic acid arabinoxylan ester (FAX) and arabinoxylan (AX); both were processed from refined corn bran (RCB) and were compared with those of cellulose(CE)- and RCB-fed rats. The enzymatic activities in the ceca changed according to the diets. Xylanase activity, arabinofuranosidase activity and ferulic acid esterase activity appeared in the cecum of the FAX- and AX-fed rats, but these activities were not observed in the cecum of CE- and RCB-fed rats. FAX and AX showed a tendency to decrease serum cholesterol levels. At first, xylanase and arabinofuranosidase were supposed to attack the FAX and AX main chain and side chain, and thus high molecular weight FAX and AX became lower molecular weight fragments. At that time, ferulic acid esterase was presumed to attack and FAX was degraded lower. These enzymes might act synergistically.

To make clear the mechanism of change of tryptophan-niacin metabolism in diabetic rats, we investigated the effect of dietary linoleic acid on the tryptophan-niacin metabolites and the activity of liver, alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD), a key enzyme of tryptophan-niacin metabolism, in streptozotocin diabetic rats, Moreover, we investigated the involvement of linoleic acid in the induction of hepatic ACMSD activity by streptozotocin diabetes, In diabetic rats, the sum of urinary excretion of nicotinamide, N-1-methylnicotinamide (MNA), N-1-methyl-2-pyridone-5-carboxamide (2-Py) and N-1-methyl-4-pyridone-3-carboxamide (4-Py) was higher in the fat free diet group than in the linoleic acid group, that was accompanied by the increase of tryptophan intake and reduction of body weight in the fat free diet group. In diabetic rats, hepatic ACMSD activity was higher in the fat free diet group than in the linoleic acid group. The results indicated that the induction of hepatic ACMSD activity by diabetes was not due to removal of the suppressive effect of the linoleic acid on the enzyme. In the diabetic + insulin group, hepatic ACMSD activity was significantly lower than in the diabetic group.

4週齢のウィスター系雄性ラットを用いて飼料中のオリゴ糖のガラクトサミン肝障害発症に及ぼす影響について検討した。<BRガラクトースを含んでいるラクチュロース, ラフィノース, 2種のガラクトオリゴ糖 (以上ビフィズス菌増殖因子), ガラクトースおよびラクトースにガラクトサミン肝障害発症抑制効果が認められた。<BR>同じビフィズス菌増殖因子であるフラクトオリゴ糖とグルコマンノオリゴ糖にはこのような効果が見られなかった。ビフィズス菌増殖因子が必ずしもガラクトサミン肝障害発症抑制効果を示さない場合があった。<BR>ガラクトサミン肝障害発症抑制にはオリゴ糖中あるいは単糖としてのガラクトースが深く関与していることが明らかにされた。

4週齢 (体重50～60g) のWistar系雄ラツトを用い, 各種タンパク質 (カゼイン (C), 卵白 (E), ツェイン (Z), 小麦グルテン (G)) の混合食がガラクトサミン肝障害ならびに四塩化炭素肝障害に及ぼす影響を血漿トランスアミナーゼ (グルタミン酸オキサロ酢酸トランスアミナーゼ (GOT), グルタミン酸ピルビン酸トランスアミナーゼ (GPT)) 活性値および血漿MR比 (遊離分枝鎖アミノ酸濃度/遊離芳香族アミノ酸濃度) を指標に検討した。<BR>1) 各種飼料をラットに14日間与えて飼育し, 14日目にD-ガラクトサミン塩酸塩溶液 (800mg/kg体重) をラットの腹腔内に注射し, 20時間後に解剖した。小麦グルテンを含んでいる (E10%+G10%, E20/3%+G20/3%+Z20/3%) 群は, ガラクトサミン投与による血漿GOT活性の上昇を, 対照群 (E20%) に比し有意に抑制したが (p<0.05), MR比は各群間に有意差は認められなかった。<BR>2) 四塩化炭素のオリーブ油溶液 (50%v/v) を背部皮下に週2回11週間注射 (1ml/kg体重) して四塩化炭素肝障害ラットを作成し (その間は市販固形飼料 (CE-2) を投与), その後各種タンパク質の混合食をラットに7日間与えた後解剖した。その結果, 小麦グルテンを含んでいる (E10%+G10%, E20/3%+G20/3%+Z20/3%) 群はカゼイン単独群 (20%C), 卵白単独群 (20%E) に比し血漿GPT活性値の上昇が認められたが, MR比は各群間有意な差は認められなかった。<BR>以上の結果から, メカニズムの異なる肝障害においては小麦グルテンは異なる作用を示すことが明らかとなった。