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PubMed1992

Action of neopullulanase. Neopullulanase catalyzes both hydrolysis and transglycosylation at alpha-(1----4)- and alpha-(1----6)-glucosidic linkages.

The transglycosylation reaction catalyzed by neopullulanase was analyzed. Radioactive oligosaccharides were produced when the enzyme acted on maltotriose in the presence of [U-14C]glucose. Some of the radioactive oligosaccharides had only alpha-(1----4)-glucosidic linkages, but others were suggested to have alpha-(1----6)-glucosidic linkages. The existence of alpha-(1----6)-glucosidic linkages in the products from maltotriose with neopullulanase was proven by proton NMR spectroscopy and methylation analysis. We previously reported that the one active center of neopullulanase catalyzes the hydrolysis of alpha-(1----4)- and alpha-(1----6)-glucosidic linkages (Kuriki, T., Takata, H., Okada, S., and Imanaka, T. (1991) J. Bacteriol. 173,6147-6152). These facts proved that neopullulanase catalyzed all four types of reactions: hydrolysis of alpha-(1----4)-glucosidic linkage, hydrolysis of alpha-(1----6)-glucosidic linkage, transglycosylation to form alpha-(1----4)-glucosidic linkage, and transglycosylation to form alpha-(1----6)-glucosidic linkage. The four reactions are typically catalyzed by alpha-amylase, pullulanase, cyclomaltodextrin glucanotransferase, and 1,4-alpha-D-glucan branching enzyme, respectively. These four enzymes have some structural similarities to one other, but reactions catalyzed by the enzymes are considered to be distinctive: the four reactions are individually catalyzed by each of the enzymes. The experimental results obtained from the analysis of the reaction of the neopullulanase exhibited that the four reactions can be catalyzed in the same mechanism.

1,4-alpha-Glucan Branching Enzyme↗

PubMed1991

The protein encoded by the rolB plant oncogene hydrolyses indole glucosides.

The rolB gene of Agrobacterium rhizogenes, whose expression stimulates the formation of roots by transformed plant tissues and other growth alterations in transgenic plants, codes for a beta-glucosidase able to hydrolyse indole-beta-glucosides. Indeed, we show that extracts of bacteria and/or plant tissue expressing the rolB protein hydrolyse indoxyl-beta-glucoside (plant indican). Because of the structural similarity between indoxyl-beta-glucoside and indole-3-acetyl-beta-glucoside (IAA-beta-glucoside), we propose that the physiological and developmental alterations in transgenic plants expressing the rolB gene could be the result of an increased intracellular auxin activity caused by the release of active auxins from inactive beta-glucosides. Thus two of the oncogenes carried by the T-DNA of the plant pathogen Agrobacterium rhizogenes (rolB and rolC) perturb plant growth and development by coding for beta-glucosidases with distinct specificities. Whereas the rolC beta-glucosidase releases cytokinins from their glucoside conjugates, the rolB encoded protein hydrolyses indole-beta-glucosides. The combined action of these two genes therefore is expected to modulate the intracellular concentration of two of the main growth factors active in plants.

Base Sequence↗

PubMed1996

Alkyl Glucosides on Hydrophobic Surfaces Studied by Surface Force and Wetting Measurements

The wetting properties of hydrophobized surfaces in the presence of alkyl glucosides have been studied using a Wilhelmy balance technique, and the interparticle forces acting between such surfaces have been investigated using the interferometric surface force apparatus. The adsorption at concentrations well below the cmc is rather limited both for the anomerically pure octyl beta-glucoside and for the technical product based on the branched octyl glucoside, 2-ethylhexyl glucoside. However, the adsorption results in a decreasing surface hydrophobicity, and consequently the force needed to separate two such surfaces from each other is reduced. At the cmc for octyl beta-glucoside, a surfactant monolayer is adsorbed on each surface. The interaction between the glucose units gives rise to a short-range repulsive force. Beyond the range of this repulsive force a weak attraction is experienced. Addition of a small amount of octyl alpha-glucoside does not change the short-range interaction significantly. The technical 2-ethylhexyl glucoside surfactant behaves similarly to the anomerically pure surfactant at low concentrations. The solution with the technical glucoside phase-separates at high surfactant concentration. It is observed that under such conditions a thick layer is deposited on each surface.

Journal Article↗

PubMed1983

Further characterization and regulation of malonyl-coenzyme A: flavonoid glucoside malonyltransferases from parsley cell suspension cultures.

Two malonyltransferases, malonyl-CoA:flavone/flavonol 7-O-glucoside malonyltransferase and malonyl-CoA:flavonol 3-O-glucoside malonyltransferase, were purified to apparent homogeneity from uv-irradiated parsley cell cultures. Both purified enzymes appear to be specific for flavonoid glycosides. Additional malonyltransferases, active toward several phenol glucosides other than flavonoids, were present in partially purified 7-O-glucoside malonyltransferase preparations. Antibodies raised against the purified 3-O-glucoside malonyltransferase did not inhibit the activity of the 7-O-glucoside malonyltransferase over a wide antibody concentration range. Determination of the rate of synthesis in vivo of the 3-O-glucoside malonyltransferase after ultraviolet light-pulse induction of parsley cells revealed two maxima at 6 and 30 h, respectively. These results indicate that the induced changes in 3-O-glucoside malonyltransferase activity were the consequence of either a repeated change in the rate of synthesis of one enzyme species or changes in the synthesis rates of more than one enzyme species.

Acyltransferases↗

PubMed2003

Glucosidation of hyodeoxycholic acid by UDP-glucuronosyltransferase 2B7.

Previous studies have shown that several endogenous compounds, such as bilirubin and certain bile acids, are glucosidated in human liver. In this work, we have identified human UDP-glucuronosyltransferase 2B7 (UGT2B7) as the isoform that catalyzes the glucosidation of hyodeoxycholic acid (HDCA). The glucosidation by UGT2B7 was specific for HDCA and was not observed with the other bile acids examined, lithocholic acid, chenodeoxycholic acid, and ursodeoxycholic acid. The kinetics of HDCA glucuronidation and glucosidation by UGT2B7 were characterized. The K(m) values for glucuronidation and glucosidation of HDCA were 11.6 and 17.9 microM, respectively, with V(max) values of 4.15 nmol/min/mg protein for glucuronidation and 3.28 nmol/min/mg for glucosidation. At a fixed concentration of HDCA, the apparent K(m) for UDP-glucuronic acid was 89 microM with a V(max) of 3.53 nmol/min/mg. The corresponding parameters for UDP-glucose were 442 microM and 1.98 nmol/min/mg, respectively. UGT2B7 catalyzed the addition of the glucose and glucuronic acid moieties to an hydroxyl group on HDCA and also possessed some capacity to use UDP-xylose as sugar donor. The two polymorphic variants of UGT2B7, UGT2B7(*)1 and UGT2B7(*)2 could both glucosidate HDCA. This is the first report that identifies UGT2B7 as the enzyme responsible for the glucosidation of the bile acid, HDCA.

Cells, Cultured↗

PubMed2000

A novel beta-glucoside-specific PTS locus from Streptococcus mutans that is not inhibited by glucose.

A regulon from Streptococcus mutans that plays a role in the utilization of beta-glucosides has been isolated, sequenced and subjected to sequence analysis. This regulon encodes a beta-glucoside-specific Enzyme II (EII) component (bglP) of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) and a phospho-beta-glucosidase (bglA) which is responsible for the breakdown of the phospho-beta-glucosides within the cell. Both the bglP and bglA gene products have significant similarity with proteins that have similar functions from Clostridium longisporum, Listeria monocytogenes, Erwinia chrysanthemi, Escherichia coli, Klebsellia oxytoca and Bacillus subtilis. The potential functions of the BglP and BglA proteins are supported by phenotypic data from both S. mutans and E. coli. A chromosomal deletion in S. mutans spanning the bglP and bglA genes resulted in a strain that was unable to hydrolyse the beta-glucoside aesculin in the presence of glucose. When glucose was removed from the medium, the deletion strain regained the ability to break down aesculin. These data suggest that S. mutans possesses an alternative mechanism from the one described in this report for breaking down beta-glucosides. This second mechanism was repressed by glucose while the regulon described here was not. Complementation studies in E. coli CC118 also suggest a potential role for this regulon in the utilization of other beta-glucosides. When a plasmid containing the 8 kb beta-glucoside-specific regulon was transformed into E. coli CC118, the transformed strain was able to break down the beta-glucoside arbutin.

Chromosome Deletion↗

PubMed1987

Toxicity of D, L-mandelonitrile-beta-D-glucoside, "prulaurasin" in rat.

Toxicity of cyanogenetic glucoside was studied with rats using synthesized D, L-mandelonitrile-beta-D-glucoside. Considering from blood cyanide level, the cause of death was presumed to be cyanide intoxication. Hydrolysis of cyanogenetic glucoside occurred mainly in small and large intestines. Cyanide level in the intestine seemed to be independent of the amount of glucoside present. LD50 value was calculated to 560 mg/kg but good dose dependent result was not obtained. Relatively rapid absorption of the glucoside from the gastrointestinal tract was observed with the highest absorption rate of 53.4% within 165 min. About 30-45% of the administered glucoside was excreted within 24 hr without alteration and dose dependence appeared in an excreted ratio. The ratio of D-mandelonitrile-beta-D-glucoside to L-form excreted in the urine or remained in the gastrointestinal tract was almost in the same as at administration, and hence biological behaviors, such as absorption, excretion and hydrolysis, of both D- and L-forms of glucoside were almost the same.

Animals↗

PubMed2005

Effect of sesaminol glucosides on beta-amyloid-induced PC12 cell death through antioxidant mechanisms.

Several lines of evidence support that beta-amyloid (Abeta)-induced neurotoxicity is mediated through the generation of reactive oxygen species (ROS) and elevation of intracellular calcium. In this study, we have investigated protective effects of sesaminol glucosides on Abeta-induced oxidative cell death in cultured rat pheochromocytoma (PC12) cells. Sesaminol glucoside (50-250microg/ml) decreased Abeta(25-35)-induced ROS generation, formation of 8-oxodG, a form of oxidative DNA and elevation of intracellular calcium level concomitant with prevention of apoptotic cell death dose dependently. Sesaminol glucoside (50-250microg/ml) also effectively decreased Abeta1-42 and ADDL form of Abeta1-42 as well as the combination of H2O2 with FeSO4-induced cell damages. In mechanistic study, sesaminol glucosides attenuated Abeta25-35-induced activation of redox transcription factor nuclear factor-kappaB NF-kappaB through inhibition of p50 translocation and IkappaB phosphorylation, and blocked NF-kappaB-dependent luciferase activity in addition to the inhibitory effect on Abeta25-35-induced activation of ERK kinase signal pathway. Consistent with the inhibitory effect on Abeta25-35-induced stress-induced cell death, sesaminol glucosides decreased expression of pro-apoptotic gene p53, and Bax and caspase-3, but enhanced expression of anti-apoptotic Bcl-2. Moreover, the protective effects of sesaminol glucoside on Abeta25-35-induced ROS generation, NF-kappaB activation and cell death were further enhanced with glutathione. This study therefore suggests that sesaminol glucosides have protective effect on Abeta-induced neuronal cell death, and its effect may be through antioxidative property.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2005

Galloyl, caffeoyl and hexahydroxydiphenoyl esters of dihydrochalcone glucosides from Balanophora tobiracola.

Seven galloyl, caffeoyl and (S)-hexahydroxydiphenoyl (HHDP) esters of dihydrochalcone glucosides were isolated from Balanophora tobiracola; based on spectroscopic and chemical evidence, their structures were determined to be 6''-O-galloyl-, 3'',4''-di-O-galloyl-, 4'',6''-di-O-galloyl-, 4'',6''-O-(S)-HHDP-, 3''-O-galloyl-4'',6''-O-(S)-HHDP-, 3''-O-caffeoyl-4'',6''-O-(S)-HHDP-3-hydroxyphloretin 4'-O-beta-D-glucosides and 3''-O-galloyl-4'',6''-O-(S)-HHDP-phloretin 4'-O-beta-D-glucoside, respectively. By contrast, these compounds were not found in the taxonomically related B. japonica. The 3''-galloyl-4'',6''-HHDP esters of the dihydrochalcone glucosides showed strong inhibitory activities against alpha-glucosidase. Four known compounds were also isolated namely, (+/-)-eriodictyol 7-O-beta-D-glucoside, 1-O-caffeoyl-3-O-galloyl-beta-D-glucose, phloretin 4'-O-beta-D-glucoside, and 3-hydroxyphloretin 4'-O-beta-D-glucoside.

Balanophoraceae↗

PubMed1990

Water-soluble proteins do not bind octyl glucoside as judged by molecular sieve chromatographic techniques.

It is well known that the non-ionic detergent octyl glucoside (1-O-n-octyl-beta-D-glucopyranoside) solubilizes biological membrane components. It forms complexes with membrane-spanning proteins by hydrophobic interactions and it forms mixed micelles with membrane lipids. In contrast, non-ionic detergents usually do not bind to water-soluble proteins. According to a recent report, substantial and cooperative binding of octyl glucoside to several water-soluble proteins does occur near the critical micelle concentration. However, data have been obtained that contradict this report. No decrease was found in the elution volumes of five water-soluble proteins on molecular sieve chromatography on two Superose columns in tandem when 35 mM octyl glucoside was included in the eluent. No binding of the detergent to these proteins was observed at 20 or 22.5 mM octyl glucoside on molecular sieve chromatography on a TSK SW guard column as determined by differential refractometry and UV spectrophotometry of the proteins in the absence or presence of octyl glucoside. The experiments were done with the same buffer system and with six of the proteins used in the reported study. It is concluded that, as expected, there is no binding of octyl glucoside to water-soluble proteins above the detection limit (0.1 g detergent/g protein) of the refractometric method. The binding of, on average, 1.3 +/- 0.2 g of detergent per gram of water-soluble protein that was observed at 20 mM octyl glucoside in the reported study is not consistent with the present results.

Chromatography, Gel↗

PubMed2003

Protective effects of cyanidin-3-O-glucoside from blackberry extract against peroxynitrite-induced endothelial dysfunction and vascular failure.

Anthocyanins are a group of naturally occurring phenolic compounds as colorants in several plants, flowers and fruits. These pigments have a great importance as quality indicators, as chemotaxonomic markers and antioxidants. The content of blackberry (Rubus species) juice was investigated by HPLC/ESI/MS using narrow bore HPLC columns. Using this method we demonstrated that cyanidin-3-O-glucoside represents about 80% of the total anthocyanin contents in blackberry extract. Here we investigated antioxidant activity of the blackberry juice and cyanidin-3-O-glucoside on the endothelial dysfunction in cells and in vascular rings exposed to peroxynitrite. In human umbilical vein endothelial cells (HUVEC) in vitro, peroxynitrite caused a significant suppression of mitochondrial respiration (38 +/- 2.1% of control cells), as measured by the mitochondrial-dependent conversion of the dye MTT to formazan. Peroxynitrite caused DNA strand breakage (63 +/- 1.9% single strand vs 3 +/- 0.9% single strand in control cells), as measured by the alkaline unwinding assay, and caused an activation of PARS, as measured by the incorporation of radiolabeled NAD(+) to nuclear proteins. Blackberry juice (different dilutions that contained 80 ppm;40 ppm;14.5 ppm of cyanidin-3-O-glucoside) and cyanidin-3-O-glucoside (as chloride) (0.085 microM; 0.028 microM; 0.0085 microM) reduced the peroxynitrite-induced suppression of mitochondrial respiration, DNA damage and PARS activation in HUVECs. Vascular rings exposed to peroxynitrite exhibited reduced endothelium-dependent relaxant responses in response to acetylcholine as well as a vascular contractility dysfunction in response to norepinephrine. The development of this peroxynitrite-induced vascular dysfunction was ameliorated by the blackberry juice (different dilutions that contained 80 ppm;40 ppm;14.5 ppm of cyanidin-3-O-glucoside) and cyanidin-3-O-glucoside (as chloride) (0.085 microM;0.028 microM;0.0085 microM). In conclusion our findings clearly demonstrate that blackberry juice containing cyanidin-3-O-glucoside is a scavenger of peroxynitrite and that exert a protective effect against endothelial dysfunction and vascular failure induced by peroxynitrite.

Anthocyanins↗

PubMed1990

Beta-glucoside permease represses the bgl operon of Escherichia coli by phosphorylation of the antiterminator protein and also interacts with glucose-specific enzyme III, the key element in catabolite control.

The beta-glucoside (bgl) operon of Escherichia coli is subject to both positive control by transcriptional termination/antitermination and negative control by the beta-glucoside-specific transport protein, an integral membrane protein known as enzyme IIBgl. Previous results led us to speculate that enzyme IIBgl exerts its negative control by phosphorylating and thereby inactivating the antiterminator protein, BglG. Specifically, our model postulated that the transport protein enzyme IIBgl exhibits protein-phosphotransferase activity in the absence of beta-glucosides. We now present biochemical evidence that the phosphorylation of protein BglG does indeed occur in vivo and that it is accompanied by the loss of antitermination activity. BglG persists in the phosphorylated state in the absence of beta-glucosides but is rapidly dephosphorylated when beta-glucosides become available for transport. Our data also suggested specific interactions between the beta-glucoside transport protein and the glucose-specific enzyme III (enzyme IIIGlc), a component of glucose transport and a key element in regulation of catabolite repression. These observations indicate that enzyme IIIGlc may, in conjunction with enzyme IIBgl, modulate the transport of beta-glucosides and the phosphorylation of the antiterminator protein. In the absence of both sugars, when the catabolite-controlled promoter of the operon is derepressed, enzyme IIIGlc may mediate tight repression of antitermination.

Bacterial Proteins↗

PubMed2005

Molecular cloning, characterization, and downregulation of an acyltransferase that catalyzes the malonylation of flavonoid and naphthol glucosides in tobacco cells.

Tobacco cells (Nicotiana tabacum L. Bright Yellow T-13) exposed to harmful naphthols accumulate them as glucosylated and further modified compounds [Taguchi et al. (2003a) Plant Sci. 164, 231-240]. In this study, we identified the accumulated compounds to be 6'-O-malonylated glucosides of naphthols. Cells treated with various phenolic compounds accumulated the flavonoids mainly as malonylglucosides. To clarify the function of this malonylation in tobacco, we isolated the cDNA encoding a malonyltransferase (NtMaT1) from a cDNA library derived from tobacco cells. The heterologous expression of the gene in Escherichia coli revealed that the recombinant enzyme had malonyltransferase activity against several phenolic glucosides such as flavonoid 7-O-glucosides, flavonoid 3-O-glucosides and naphthol glucosides. The substrate preference of the enzyme was similar to that of the tobacco cell extract. Malonylation activity in the transgenic cells markedly decreased with the suppression of the expression of NtMaT1 mRNA in tobacco BY-2 cells by RNA interference. The compounds administered to the transgenic cells were accumulated in the cells as glucosides or other modified compounds in place of malonylglucosides. These results show that NtMaT1 is the main catalyst of malonylation on glucosides of xenobiotic flavonoids and naphthols in tobacco plants.

Acyltransferases↗

PubMed1999

The bvr locus of Listeria monocytogenes mediates virulence gene repression by beta-glucosides.

The beta-glucoside cellobiose has been reported to specifically repress the PrfA-dependent virulence genes hly and plcA in Listeria monocytogenes NCTC 7973. This led to the hypothesis that beta-glucosides, sugars of plant origin, may act as signal molecules, preventing the expression of virulence genes if L. monocytogenes is living in its natural habitat (soil). In three other laboratory strains (EGD, L028, and 10403S), however, the effect of cellobiose was not unique, and all fermentable carbohydrates repressed hly. This suggested that the downregulation of virulence genes by beta-glucosides is not a specific phenomenon but, rather, an aspect of a global regulatory mechanism of catabolite repression (CR). We assessed the effect of carbohydrates on virulence gene expression in a panel of wild-type isolates of L. monocytogenes by using the PrfA-dependent phospholipase C gene plcB as a reporter. Utilization of any fermentable sugar caused plcB repression in wild-type L. monocytogenes. However, an EGD variant was identified in which, as in NCTC 7973, plcB was only repressed by beta-glucosides. Thus, the regulation of L. monocytogenes virulence genes by sugars appears to be mediated by two separate mechanisms, one presumably involving a CR pathway and another specifically responding to beta-glucosides. We have identified in L. monocytogenes a 4-kb operon, bvrABC, encoding an antiterminator of the BglG family (bvrA), a beta-glucoside-specific enzyme II permease component of the phosphoenolpyruvate-sugar phosphotransferase system (bvrB), and a putative ADP-ribosylglycohydrolase (bvrC). Low-stringency Southern blots showed that this locus is absent from other Listeria spp. Transcription of bvrB was induced by cellobiose and salicin but not by arbutin. Disruption of the bvr operon by replacing part of bvrAB with an interposon abolished the repression by cellobiose and salicin but not that by arbutin. Our data indicate that the bvr locus encodes a beta-glucoside-specific sensor that mediates virulence gene repression upon detection of cellobiose and salicin. Bvr is the first sensory system found in L. monocytogenes that is involved in environmental regulation of virulence genes.

Bacterial Proteins↗

PubMed2004

Involvement of Streptococcus gordonii beta-glucoside metabolism systems in adhesion, biofilm formation, and in vivo gene expression.

Streptococcus gordonii genes involved in beta-glucoside metabolism are induced in vivo on infected heart valves during experimental endocarditis and in vitro during biofilm formation on saliva-coated hydroxyapatite (sHA). To determine the roles of beta-glucoside metabolism systems in biofilm formation, the loci of these induced genes were analyzed. To confirm the function of genes in each locus, strains were constructed with gene inactivation, deletion, and/or reporter gene fusions. Four novel systems responsible for beta-glucoside metabolism were identified, including three phosphoenolpyruvate-dependent phosphotransferase systems (PTS) and a binding protein-dependent sugar uptake system for metabolizing multiple sugars, including beta-glucosides. Utilization of arbutin and esculin, aryl-beta-glucosides, was defective in some mutants. Esculin and oligochitosaccharides induced genes in one of the three beta-glucoside metabolism PTS and in four other genetic loci. Mutation of genes in any of the four systems affected in vitro adhesion to sHA, biofilm formation on plastic surfaces, and/or growth rate in liquid medium. Therefore, genes associated with beta-glucoside metabolism may regulate S. gordonii in vitro adhesion, biofilm formation, growth, and in vivo colonization.

Bacterial Adhesion↗

PubMed1998

BglF, the sensor of the bgl system and the beta-glucosides permease of Escherichia coli: evidence for dimerization and intersubunit phosphotransfer.

The Escherichia coli BglF protein, also designated EIIbgl, is an enzyme II of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) that catalyzes transport and phosphorylation of beta-glucosides. In addition, BglF has the ability, unusual for an EII, to regulate the activity of a transcriptional regulator, BglG, by phosphorylating and dephosphorylating it according to beta-glucoside availability. Together, BglF and BglG constitute a novel sensory system. The membrane-bound sensor, BglF, has two phosphorylation sites: site 1 accepts a phosphoryl group from HPr and delivers it to site 2; site 2 delivers the phosphoryl group either to beta-glucosides or to BglG. Here, we provide several lines of evidence for the dimerization of BglF and for the occurrence of productive intersubunit phosphotransfer within the BglF dimers. (1) Two inactive BglF mutant proteins, one lacking phosphorylation site 1 and the other lacking site 2, complement one another to allow beta-glucoside utilization by bglF strains. (2) The pairs of mutant proteins complement one another in regulating BglG activity as a transcriptional antiterminator in vivo. (3) Only when they are present in the same membrane preparation do the mutant protein pairs efficiently transfer the phosphoryl group from HPr to beta-glucosides and to BglG in vitro. (4) Gentle extraction of cellular proteins followed by SDS-PAGE reveals the existence of BglF homodimers. A portion of the phosphorylated form of BglF can also be extracted from the membrane as a dimer. Dimerization is mediated by the membrane-bound IICbgl domain, as indicated by the dimerization of IICbgl by itself and of BglF derivatives that contain this domain. Since dimers persist in the presence of a reducing agent, they are apparently not held together by disulfide bonds. Rather, BglF dimerization might involve hydrophobic interactions between residues in the membrane-spanning domain. In addition, we show that BglF dimerization is not modulated by beta-glucosides and is therefore not part of the mechanism that diverts the phosphoryl group away from BglG to the transported sugar upon addition of beta-glucosides to the growth medium.

Biosensing Techniques↗

PubMed1993

New norcucurbitacin and heptanorcucurbitacin glucosides from Fevillea trilobata.

From the MeOH extract of the seeds of Fevillea trilobata (Cucurbitaceae) were isolated fevicordin A glucoside [1], cayaponoside B [2], cayaponoside D [3], a new norcucurbitacin glucoside, and a new heptanorcucurbitacin glucoside. The structure of the new norcucurbitacin glucoside, andirobicin A glucoside, was established as 29-nor-1,2,3,4,5,10-dehydro-25-methoxy-2-O-beta-D-glucopyranosyl- 3,16 alpha,20R,22 xi-tetrahydroxy-11-oxocucurbit-23-ene [4], and that of the novel heptanorcucurbitacin glucoside, andirobicin B glucoside, as 22,23,24,25,26,27,29-heptanor-1,2,3,4,5,10-dehydro-2-O-beta-D-g luc opyranosyl-3,16 alpha-dihydroxycucurbita-11,20-dione [5].

Antineoplastic Agents, Phytogenic↗

PubMed2003

Bioavailability of soybean isoflavones from aglycone and glucoside forms in American women.

BACKGROUND: Test results on the bioavailability of isoflavones in the aglycone or glucoside form in Eastern and Western human subjects are contradictory. OBJECTIVE: The objective was to investigate the bioavailability of the soy isoflavones daidzein and genistein in American women with typical American dietary habits after ingestion of the aglycone or glucoside form of isoflavones. DESIGN: Fifteen American women aged 46 +/- 6 y participated in a randomized, double-blind study. Blood samples were collected 0, 1, 2, 4, 8, 12, 24, and 48 h after consumption of aglycone or glucoside tablets with breakfast. The plasma curves for daidzein, genistein, and equol were constructed and the postprandial maximum concentration (C(max)), time to the maximum concentration (t(max)), and area under the curve (AUC) were determined. RESULTS: Isoflavone concentrations peaked early (1-2 h) in plasma and peaked again at 4-8 h. Mean C(max), t(max), and AUC values for genistein were not significantly different after ingestion of aglycone or glucoside. However, C(max) and AUC values, but not t(max), were significantly higher for daidzein after aglycone ingestion, which was partly due to its higher content in the aglycone tablets. Equol appeared after 4 h and remained elevated after 48 h. Despite a higher content of daidzein in the aglycone tablets, the AUC for equol was significantly higher after ingestion of the glucoside tablets, probably because of the metabolic action of intestinal bacteria during the long intestinal transit time of glucoside. CONCLUSION: The apparent bioavailability of genistein and daidzein is not different when consumed as either aglycone or glucoside by American women.

Adult↗