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T Akao

Publications and source records attributed to T Akao.

At least 91 records · Page 5Linked to original sources
PubMed1991

Enzymatic sulfation of polyphenols related to tannins by arylsulfotransferase.

This report discusses a novel type of arylsulfotransferase (AST) which was derived from human intestinal bacterium sulfated polyphenolic compounds when p-nitrophenyl sulfate (PNS) was taken as a donor substrate. (+)-Catechin, (+/-)-catechin, (-)-epicatechin and (-)-epicatechin gallate were better substrates than tyramine. (-)-Epigallocatechin and (-)-epigallocatechin gallate were slightly worse substrates than tyramine. Although gallic acid was a bad substrate, alkyl gallate esters were better substrates than tyramine. The degree of acceptor specificity increased in proportion to the length of the alkyl group up to the carbon number of five. Pedunculagin, geraniin and corilagin were less effective than tyramine. Rosmarinic acid and penta-O-galloyl-beta-D-glucose were similarly well sulfated. Two products, 4'-monosulfate and 4',5-disulfate of (+)-catechin, were detected at a two-fold molar excess of PNS over (+)-catechin. When (+)-catechin-4'-monosulfate as an acceptor was enzymatically sulfated with PNS as a donor, only the 4',5-disulfate was produced. Thus, arylsulfotransferase was useful for the convenient preparation of sulfate esters of polyphenols at their specific hydroxyl groups.

Arylsulfotransferase↗
PubMed1991

Metabolism of aloesin and related compounds by human intestinal bacteria: a bacterial cleavage of the C-glucosyl bond and the subsequent reduction of the acetonyl side chain.

By anaerobic incubation with a bacterial mixture from human feces, aloesin (aloeresin B; 1) was converted to 2-acetonyl-7-hydroxy-5-methylchromone (aloesone; 3) and dl-7-hydroxy-2-(2'-hydroxypropyl)-5-methylchromone (aloesol; 4a + 4b) through a cleavage of the C-glucosyl bond, followed by reduction of the acetonyl side chain. An analogous compound, aloeresin A (2), was converted to p-coumaric acid and aloesin (1), the latter being subsequently transformed to aloesone (3) and dl-aloesol (4a + 4b). On the other hand, 7-O-methylated derivatives (7, 5a and 5b) of aloesin and of 8-C-glucosylaloesol were not cleaved to the corresponding aglycones, suggesting the importance of a free hydroxy group adjacent to the C-glucosyl group in the molecule for the bacterial cleavage of aloesin derivatives. This is the first report on the cleavage of the C-glycosyl bond of chromone C-glucosides by intestinal bacteria.

Acetone↗
PubMed1991

Barbaloin stimulates growth of Eubacterium sp. strain BAR, a barbaloin-metabolizing bacterium from human feces.

Eubacterium sp. strain BAR, isolated from human feces, transformed barbaloin to aloe-emodin anthrone in a basal medium lacking carbohydrate. Barbaloin remarkably stimulated the growth of strain BAR in the basal medium, the stimulative extent of the growth depending on the amount of barbaloin added. The addition of D-glucose, D-galactose, maltose, cellobiose, sucrose or D-amygdalin to the basal medium containing barbaloin caused a decrease of the growth stimulated by barbaloin to the growth level with each sugar, resulting in a complete inhibition of the barbaloin transformation. On the other hand, the addition of D-fructose, which itself stimulated the growth of strain BAR, further increased the growth in the presence of barbaloin and little inhibited barbaloin transformation. Nojirimycin bisulfite, a specific inhibitor of glucosidases, potently inhibited the growth with barbaloin, but did not affect the growth with glucose or cellobiose. Also, nojirimycin bisulfite completely inhibited the transformation of barbaloin to aloe-emodin anthrone. These results indicate that a unique enzyme capable of cleaving the C-glycosyl bond is induced in strain BAR by barbaloin and, consequently, strain BAR grows by utilizing as a nutrient the carbohydrate liberated from barbaloin. It is further suggested that the barbaloin-cleaving enzyme is inhibited by nojirimycin bisulfite and that the induction of the enzyme is repressed with D-glucose and D-galactose.

Anthracenes↗
PubMed1991

[Combination chemotherapy of methotrexate, etoposide, adriamycin and cisplatin (M-EAP) for advanced urothelial cancer].

Combination chemotherapy with methotrexate, etoposide, adriamycin and cisplatin (M-EAP regimen) was administered to 4 patients with advanced epithelial cancer of the urinary tract (Methotrexate 30 mg/M2 day 1, 15 and 22; Etoposide 100 mg/M2 day 1, 2, 15 and 22; Adriamycin 30 mg/M2 day 2; Cisplatin 70 mg/M2 day 2, every 4 weeks). In an attempt to improve the anti-cancer effect of the M-VAC regimen, etoposide was substituted for vinblastine. This series comprised 3 males and 1 female ranging in age from 54 to 68 years (mean age: 63), with a performance status of 1 to 2. The site of the primary lesion was bladder in 3, and left ureter in 1. The clinical response was assessed in 3 of the 4 patients: one achieved complete response and two had partial response. Two of the four died of disease 5 months after chemotherapy. Two of them have been alive for 10 and 8 months with no evidence of disease after chemotherapy. Toxicity included moderate or severe myelosuppression in two patients, and mild to moderate anorexia, vomiting, alopecia, and hiccups in all patients. These preliminary results suggest that the M-EAP regimen is effective against advanced epithelial carcinoma of the urinary tract. However, myelosuppression was a dose-limiting factor.

Aged↗
PubMed1990

Characterization of NADP+: 3 beta-hydroxysteroid dehydrogenase from microsomes of rat liver.

A NADP(+)-dependent 3 beta-hydroxysteroid dehydrogenase activity was localized in the microsomal fraction of rat liver. This enzyme was solubilized and separated completely from 3 alpha-hydroxysteroid dehydrogenase by Matrex red A column chromatography. Partially purified 3 beta-hydroxysteroid dehydrogenase catalyzed the oxidation and reduction between the 3 beta-hydroxyl and 3-ketonic group of steroids or bile acids having no double bond in the A/B ring, but was inactive toward 3 alpha-hydroxyl group. The enzyme required NADP+ for oxidation and NADPH for reduction. The activity was inhibited by p-chloromercuribenzoic acid or p-chloromercuribenzenesulfonic acid at the concentration of 10(-4) M. The molecular weight of the enzyme was estimated to be about 43,000 by Sephadex G-200 column chromatography. From these results, it is concluded that the enzyme is a new type of microsomal NADP+:3 beta-hydroxysteroid dehydrogenase.

3-Hydroxysteroid Dehydrogenases↗
PubMed1990

Metabolism of glycyrrhetic acid by rat liver microsomes-II. 22 alpha- and 24-hydroxylation.

18 beta-Glycyrrhetic acid (GA, an aglycone of glycyrrhizin) is converted to 3-oxo-18 beta-glycyrrhetic acid (3-oxoGA) in the presence of NADP+ by rat liver homogenates, but GA was converted in the presence of NADPH to two other metabolites showing lower Rf values on thin-layer chromatography (TLC) than those of GA and 3-oxoGA by postmitochondrial supernatant of rat liver. The GA-metabolizing activity in the presence of NADPH was localized in microsomes, similar to localization of GA-oxidizing activity to 3-oxoGA. The GA-metabolizing activity required NADPH as a cofactor and O2 for full activity and was inhibited with CO, suggesting the hydroxylation reaction of GA by cytochrome P450. Two metabolites (I and II, lower and higher Rf values on TLC, respectively) were purified on preparative TLC. Mass spectral (MS) analyses of II and methyl ester of acetylated I indicated the formation of monohydroxylated metabolites. On the basis of 3H- and 13C-NMR assignments I and II were identified to be 22 alpha- and 24-hydroxy-18 beta-glycyrrhetic acids, respectively. 3-OxoGA and 3-epi-18 beta-glycyrrhetic acid (3-epiGA) seem to be also hydroxylated at C-22 and C-24. A metabolite of 3-oxoGA showing a lower Rf value was also identified as 22 alpha-hydroxy-3-oxo-18 beta-glycyrrhetic acid by MS and 3H- and 13C-NMR spectral analyses. In 22 alpha-hydroxylation the best substrate was 3-oxoGA, followed by GA and 3-epiGA. On the other hand, for 24-hydroxylation the best substrate was GA, then 3-oxoGA, and 3-epiGA in order. However, 18 alpha-glycyrrhetic acid (18 alpha-GA) was a poor substrate for both 22 alpha- and 24-hydroxylation.

Animals↗
PubMed1990

Metabolism of glycyrrhetic acid by rat liver microsomes: glycyrrhetinate dehydrogenase.

Glycyrrhetic acid, derived from a main component of liquorice, was converted to 3-ketoglycyrrhetic acid reversibly by rat liver homogenates in the presence of NADPH or NADP+. Glycyrrhetic acid-oxidizing and 3-ketoglycyrrhetic acid-reducing activities were localized in microsomes among the subcellular fractions of rat liver. Glycyrrhetic acid-oxidizing activity and 3-ketoglycyrrhetic acid-reducing activities showed pH optima at 6.3 and 8.5, respectively, and required NADP+ or NAD+ and NADPH or NADH, respectively, indicating that these activities were due to glycyrrhetinate dehydrogenase. The dehydrogenase was not solubilized from the membranes by the treatment with 1 M NaCl or sonication, indicating that the enzyme is a membrane component. The dehydrogenase was solubilized with detergents such as Emalgen 913, Triton X-100 and sodium cholate, and then separated from 3 beta-hydroxysteroid dehydrogenase (5 beta-androstan-3 beta-ol-17-one-oxidizing activity) by butyl-Toyopearl 650 M column chromatography. Partially purified enzyme catalyzed the reversible reaction between glycyrrhetic acid and 3-ketoglycyrrhetic acid, but was inactive toward 3-epiglycyrrhetic acid and other steroids having the 3 beta-hydroxyl group. The enzyme required NADP+ and NADPH for the highest activities of oxidation and reduction, respectively, and NAD+ and NADH for considerable activities, similar to the results with microsomes. From these results the enzyme is defined as glycyrrhetinate dehydrogenase, being quite different from 3 beta-hydroxysteroid dehydrogenase of Ruminococcus sp. from human intestine, which is active for both glycyrrhetic acid and steroids having the 3 beta-hydroxyl group.

3-Hydroxysteroid Dehydrogenases↗
PubMed1990

Synthetic cationic amphiphiles for liposome-mediated DNA transfection.

The compounds with efficient DNA transfection ability into eukaryotic cells were searched from various synthetic amphiphiles which have cationic heads and long saturated hydrocarbon tails. The efficiency of amphiphiles in gene transfer was examined by the transient expression of cytochrome b5 from its cDNA in COS cells. Among various synthetic amphiphiles, including N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride which is commercially available lipid, O,O'-didodecyl-N-[p-(2-trimethylammonioethyloxy)benzoyl]-(L) -glutamate bromide was highest in efficiency. The optimum condition for the amount of the amphiphile and DNA, and the incubation time were established to be 7.5-15 micrograms/22 mm dish and 1-10 micrograms/22 mm dish, and 48-72 h, respectively.

Animals↗
PubMed1988

Purification and properties of 3 alpha-hydroxyglycyrrhetinate dehydrogenase of Clostridium innocuum from human intestine.

3 alpha-Hydroxyglycyrrhetinate dehydrogenase of Clostridium innocuum, isolated from human intestinal bacteria, was capable of converting 3-ketoglycyrrhetic acid to 3 alpha-hydroxyglycyrrhetic acid. The enzyme was purified to homogeneity by means of butyl-Toyopearl 650M, Sephadex G-150, Matrex Red A, Toyopearl HW-55S, and isoelectric focusing column chromatographies. The purified enzyme showed a specific activity of 156 mumol/min.mg toward 3 alpha-hydroxyglycyrrhetic acid, and showed a single band on SDS-polyacrylamide gel electrophoresis. The apparent molecular weight was 53,000, as estimated by gel filtration, and 30,000, as judged by SDS-polyacrylamide gel electrophoresis. Its isoelectric point was 5.2. The enzyme showed absolute specificity for the 3 alpha-hydroxyl and 3-ketonic groups of 18 alpha- or 18 beta-glycyrrhetic acid and required NADP+ and NADPH as cosubstrates. The enzyme did not act on any 3 alpha-hydroxyl or 3-ketonic group of steroids or bile acids. The enzyme is a novel type of enzyme, defined as 3 alpha-hydroxy-glycyrrhetinate dehydrogenase, being quite different from 3 alpha-hydroxysteroid dehydrogenase [EC 1.1.1.50].

3-Hydroxysteroid Dehydrogenases↗
PubMed1988

Glycyrrhizin stimulates growth of Eubacterium sp. strain GLH, a human intestinal anaerobe.

Eubacterium sp. strain GLH was isolated from human feces and produced two kinds of beta-D-glucuronidase (EC 3.2.1.31), one new enzyme specific for glycyrrhizin (GL) and the other for phenyl beta-D-glucuronides. GL or p-nitrophenyl-mono-beta-D-glucuronide (pNPG) stimulated the production of GL or pNPG beta-glucuronidases and the growth of strain GLH in a basal medium lacking carbohydrate. D-Glucuronic acid also stimulated the growth of the bacterium, but glycyrrhetic acid did not. The increase of GL beta-glucuronidase paralleled the growth of the Eubacterium strain in pure culture. These results suggest that glucuronides such as GL and pNPG stimulate the growth of the Eubacterium strain in a nutrient-poor medium by providing D-glucuronic acid through the activity of beta-glucuronidases. The increase in GL beta-glucuronidase activity in the presence of GL was observed during the cultivation of human intestinal flora in a general anaerobic medium. During mixed cultivation of the Eubacterium strain with Streptococcus faecalis, which does not produce GL beta-glucuronidase, GL beta-glucuronidase was also increased by GL or pNPG, but not by glycyrrhetic acid and p-nitrophenol. It is suggested that GL stimulates the growth of strain GLH even in the mixed culture.

Anti-Bacterial Agents↗
PubMed1988

Metabolism of sennosides by human intestinal bacteria.

During the course of studies on the metabolism of sennosides by human intestinal bacteria, an enzyme which takes part in the reduction of sennosides and sennidins was originally isolated from Peptostreptococcus intermedius. This enzyme catalyzed the electron transfer from NADH to FAD, FMN or benzyl viologen, which reduced nonenzymatically sennosides and sennidins to 8-glucosyl-rhein anthrone and rhein anthrone, respectively.

Anthraquinones↗
PubMed1987

Enzymes involved in the formation of 3 beta, 7 beta-dihydroxy-12-oxo-5 beta-cholanic acid from dehydrocholic acid by Ruminococcus sp. obtained from human intestine.

Ruminococcus sp. PO1-3 from human intestinal flora reduced dehydrocholic acid to 3 beta-hydroxy-7,12-dioxo-5 beta-cholanic acid by means of the enzyme 3 beta-hydroxysteroid dehydrogenase (Akao, T., Akao, T., Hattori, M., Namba, T. and Kobashi, K. (1986) J. Biochem. (Tokyo) 99, 1425-1431). This bacterium and its crude extract gave rise to another product, showing a lower RF value on TLC, from dehydrocholic acid. The product was identified as 3 beta, 7 beta-dihydroxy-12-oxo-5 beta-cholanic acid. The crude extract reduced 7-ketolithocholic acid and its methyl ester, but not 6-ketolithocholic acid and 12-ketochenodeoxycholic acid, in the presence of NADPH, and oxidized ursodeoxycholic acid and beta-muricholic acid, but not cholic acid, chenodeoxycholic acid, deoxycholic acid and hydrocholic acid, in the presence of NADP+. Therefore, besides 3 beta-hydroxysteroid dehydrogenase, 7 beta-hydroxysteroid dehydrogenase was shown to be present in this bacterium. The two dehydrogenases were clearly separated from each other by butyl-Toyopearl 650 M column chromatography. From dehydrocholic acid, 7 beta-hydroxy-3,12-dioxo-5 beta-cholanic acid was produced by 7 beta-hydroxysteroid dehydrogenase and 3 beta, 7 beta-dihydroxy-12-oxo-5 beta-cholanic acid was produced by combination of two enzymes, 7 beta- and 3 beta-hydroxysteroid dehydrogenase.

3-Hydroxysteroid Dehydrogenases↗
PubMed1987

Purification and characterization of 7 beta-hydroxysteroid dehydrogenase from Ruminococcus sp. of human intestine.

7 beta-Hydroxysteroid dehydrogenase (7 beta-HSD) was produced by Ruminococcus sp. PO1-3 obtained from among human intestinal bacteria. The enzyme was purified from a crude extract by ammonium sulfate fractionation, and Butyl-Toyopearl 650M, Sephadex G-150, Matrex Red A and Octyl-Sepharose chromatographies. The purified enzyme was obtained as a single band on polyacrylamide gel electrophoresis with enzyme activity staining and as one band corresponding to a molecular weight of 30,000 on SDS-polyacrylamide gel electrophoresis. On gel filtration, its apparent molecular weight was estimated to be 60,000. The enzyme had a sulfhydryl group(s) in its active site. Substrate specificity studies revealed that the enzyme showed absolute specificity for the beta-configuration of a hydroxyl group at the 7 position of bile acids, and required NADP+ and NADPH as cosubstrates. The Km values for ursodeoxycholic acid, 7-k etolithocholic acid, NADP+, and NADPH were 5.0, 8.5, 7.7, and 24 microM, respectively.

Bacterial Proteins↗