Showing papers on "Glucoside published in 2001"

Color and stability of pigments derived from the acetaldehyde-mediated condensation between malvidin 3-O-glucoside and (+)-catechin.

Abstract: A pigment derived from the acetaldehyde-mediated condensation between (+)-catechin and malvidin 3-O-glucoside has been prepared and isolated by semipreparative HPLC, and its characteristics of color and stability have been studied and compared with that of malvidin glucoside in aqueous solutions. When the pH was increased from 2.2 to 5.5, the solution of the pigment became progressively more violet (lambda(max) = 560 nm at pH 5.5), whereas similar solutions of the anthocyanin were almost colorless at pH 4.0. This behavior indicated that the anthocyanin moiety of the pigment was more protected against water attack, and thus the formation of its quinonoidal forms was favored. The color of the pigment also showed more stability with regard to bleaching by SO(2) than that of malvidin glucoside. Nevertheless, the pigment was more sensitive to degradation in aqueous solution than the anthocyanin. The cleavage of the ethyl bridge that links the anthocyanin and the catechin constituted the first step in its degradation, as demonstrated by the formation of malvidin glucoside as a major product.

Major changes in human ocular UV protection with age

Abstract: PURPOSE: Age-dependent human lens coloration may be explained by the binding of UV filters to crystallins. It has been proposed that glutathione may compete for reaction with UV filter degradation products and therefore protect crystallins from modification. To understand this process, UV filters were quantified together with oxidized and reduced glutathione in human lenses of varying age. METHODS: Lens tissues were homogenized in ethanol to extract the UV filters. Metabolites were quantified by HPLC and correlations between them in the nuclear and cortical regions of the lens were examined. RESULTS: The concentrations of the UV filters 3-hydroxykynurenine, kynurenine, and 3-hydroxykynurenine glucoside decreased linearly with age, with slightly lower levels in the nucleus than the cortex. 4-(2-Amino-3-hydroxyphenyl)-4-oxobutanoic acid glucoside was found in higher levels in the nucleus than the cortex and decreased slowly in both regions with age. Glutathionyl-3-hydroxykynurenine glucoside was present in higher concentrations in the nucleus, barely detectable in young lenses, but increased significantly after age 50. Reduced glutathione levels were lower in the nucleus and decreased in both regions with age, yet oxidized glutathione increased in the nucleus but remained constant in the cortex. CONCLUSIONS: Results are consistent with a predominantly nuclear origin for both 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid glucoside and glutathionyl-3-hydroxykynurenine glucoside. This is in accord with their proposed mechanism of formation, which involves an initial deamination of 3-hydroxykynurenine glucoside. This process is more pronounced in older lenses, possibly because of the barrier to diffusion. The barrier may also explain the increase in nuclear oxidized glutathione that is observed with age. Language: en

Glucuronide and glucoside conjugation of mycophenolic acid by human liver, kidney and intestinal microsomes

Abstract: Mycophenolic acid (MPA) is primarily metabolized to a phenolic glucuronide (MPAG) as well as to two further minor metabolites: an acyl glucuronide (AcMPAG) and a phenolic glucoside (MPAG1s). This study presents investigations of the formation of these metabolites by human liver (HLM), kidney (HKM), and intestinal (HIM) microsomes, as well as by recombinant UDP-glucuronosyltransferases. HLM (n=5), HKM (n=6), HIM (n=5) and recombinant UGTs were incubated in the presence of either UDP-glucuronic acid or UDP-glucose and various concentrations of MPA. Metabolite formation was followed by h.p.l.c. All microsomes investigated formed both MPAG and AcMPAG. Whereas the efficiency of MPAG formation was greater with HKM compared to HLM, AcMPAG formation was greater with HLM than HKM. HIM showed the lowest glucuronidation efficiency and the greatest interindividual variation. The capacity for MPAGls formation was highest in HKM, while no glucoside was detected with HIM. HKM produced a second metabolite when incubated with MPA and UDP-glucose, which was labile to alkaline treatment. Mass spectrometry of this metabolite in the negative ion mode revealed a molecular ion of m/z 481 compatible with an acyl glucoside conjugate of MPA. All recombinant UGTs investigated were able to glucuronidate MPA with K:(M:) values ranging from 115.3 to 275.7 microM l(-1) and V(max) values between 29 and 106 pM min(-1) mg protein(-1). Even though the liver is the most important site of MPA glucuronidation, extrahepatic tissues particularly the kidney may play a significant role in the overall biotransformation of MPA in man. Only kidney microsomes formed a putative acyl glucoside of MPA.

Quercetin Glucuronides but Not Glucosides Are Present in Human Plasma after Consumption of Quercetin-3-Glucoside or Quercetin-4′-Glucoside

Abstract: The nature of quercetin conjugates present in blood after consumption of quercetin glucosides is still unclear. In this study, we analyzed plasma of volunteers that had consumed 325 micromol of either quercetin-3-glucoside or quercetin-4'-glucoside as an oral solution. Quercetin metabolites were extracted with acetonitrile/phosphoric acid and these extracts were analyzed using a high performance liquid chromatography with Coularray detection that distinguishes between the glucuronidated and the glucosylated forms of quercetin. No intact quercetin glucosides and only trace amounts of aglycone were found in human plasma, irrespective of the glucoside ingested. This was confirmed by spiking the plasma with glucoside standards. The major components in plasma had the same retention time as quercetin glucuronide standards. These plasma components disappeared after treatment of the plasma with bovine liver beta-glucuronidase, under reformation of quercetin, and showed the same oxidation pattern as the glucuronides. These results suggest that after consumption of quercetin glucosides, quercetin glucuronides are major metabolites in plasma.

Betalains and phenolics in red beetroot (Beta vulgaris) peel extracts: extraction and characterisation.

Abstract: The extraction of red beetroot (Beta vulgaris) peel betalains and phenolics was compared with two extraction methods and solvents. The content of total phenolics in the extracts was determined according to a modification of the Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE). The profiles of extracts were analysed by high-performance liquid chromatography (HPLC). The compounds of beetroot peel extracted with 80% aqueous methanol were characterised from separated fractions using HPLC- diode array detection (HPLC-DAD) and HPLC-electrospray ionisation-mass spectrometry (HPLC-ESI-MS) techniques. The extraction methods and the choice of solvent affected noticeably the content of individual compounds in the extract. The betalains found in beetroot peel extract were vulgaxanthin I, vulgaxanthin II, indicaxanthin, betanin, prebetanin, isobetanin and neobetanin. Also cyclodopa glucoside, N-formylcyclodopa glucoside, glucoside of dihydroxyindol-carboxylic acid, betalamic acid, L-tryptophan, p-coumaric acid, ferulic acid and traces of unidentified flavonoids were detected.

Analysis of Molecular Species of Glycolipids in Fruit Pastes of Red Bell Pepper (Capsicum annuum L.) by High-Performance Liquid Chromatography−Mass Spectrometry

Abstract: Five major glycolipid classes (acylated steryl glucoside, steryl glucoside, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and glucocerebroside) from fruit pastes of red bell pepper were separated by silica gel column chromatography. The molecular species of each glycolipid were separated and characterized by reversed-phase high-performance liquid chromatography coupled with on-line mass spectrometry using atmospheric pressure chemical ionization. The molecular species of steryl glucoside were β-sitosteryl and campesteryl glucosides, and those of the acylated steryl glucoside were their fatty acid esters. The dilinolenoyl species was predominant in monogalactosyldiacylglycerol in addition to small amounts of another five molecular species, whereas digalactosyldiacylglycerol consisted of seven molecular species varying in their degree of unsaturation. The glucocerebroside class contained at least seven molecular species, which were characterized by proton nuclear magnetic resonance spectroscopy....

New acetophenone glucosides isolated from extracts of Helichrysum italicum with antiinflammatory activity.

Abstract: Three new acetophenone glucosides (4−6), three known aglycons (1−3), and a benzo-γ-pyrone glucoside (7) were isolated from the CH2Cl2, EtOAc, and BuOH extracts from the aerial parts of Helichrysum italicum All the compounds tested showed antiinflammatory activity in a 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced mouse ear edema test, and the ID50 value of compound 2, the most active compound, was determined

Antiproliferative constituents in the plants 7. Leaves of Clerodendron bungei and leaves and bark of C. trichotomum.

Abstract: The constituents of the leaves of Clerodendron bungei STEUD. (Verbenaceae) and leaves and bark of C. trichotomum THUNB. were investigated guided by the antiproliferative activity against three tumor cell lines (MK-1: human gastric adenocarcinoma, HeLa: human uterus carcinoma, and B16F10: murine melanoma). Two phenylethanoid glycoside caffeic acid esters, acteoside and isoacteoside, were isolated as the constituents which selectively inhibit the growth of B16F10 cells. The antiproliferative activities against B16F10 cells of acteoside (GI50: 8 microM), isoacteoside (8 microM) and their methanolysis products, methyl caffeate (26 microM), 3,4-dihydroxyphenethyl alcohol (8 microM), 3,4-dihydroxyphenethyl glucoside (10 microM), desrhamnosyl acteoside (6 microM), and desrhamnosyl isoacteoside (6 microm) suggested that the 3,4-dihydroxyphenethyl alcohol group might be more responsible for the activities of acteoside and isoacteoside than the caffeoyl group. The activities of chlorogenic acid, 3,4-dihydroxyphenylacetic acid, 3-(3,4-dihydroxyphenyl) alanine, 3,4-dihydroxy-phenethylamine hydrochloride, ferulic acid, sinapic acid, and five dihydroxybenzoic acids were also determined and compared with those of the above compounds.

Purification and characterization of a beta-glucosidase from Citrus sinensis var. Valencia fruit tissue.

Abstract: A preliminary survey demonstrated activity for alpha-D-glucosidase, alpha-D-mannosidase, alpha-L-arabinosidase, beta-D-glucosidase, beta-D-xylosidase, and beta-D-galactosidase in orange fruit flavedo and albedo tissue. alpha-L-Rhamnosidase was not detected. Subsequently, a beta-glucosidase was purified from mature fruit rag tissue (composed of intersegmental septa, squeezed juice sacs, and fruit core tissue) of Citrus sinensis var. Valencia. The beta-glucosidase exhibited low levels of activity against p-nitrophenyl-beta-D-fucopyranoside (13.5%) and p-nitrophenyl-alpha-D-glucopyranoside (7.0%), compared to its activity against p-nitrophenyl-beta-D-glucopyranoside (pNPG, 100%). The enzyme was purified by a combination of ion exchange (anion and cation) and gel filtration (Superdex and Toyopearl HW-55S) chromatography. It has an apparent molecular mass of 64 kDa by denaturing electrophoresis or 55 kDa by gel filtration chromatography (BioGel P-100). Hydrolysis of pNPG demonstrated a pH optimum between 4.5 and 5.5. At pH 5.0 the temperature optimum was 40 degrees C. At pH 5.0 and 40 degrees C the K(m) for pNPG was 0.1146 mM and it had a V(max) of 5.2792 nkatal x mg(-1) protein (katal = 0.06 International Units = the amount of enzyme that produces, under standard conditions, one micromol of product per min). Of the substrates tested, the enzyme was most active against the disaccharide cellobiose (1-->4), but was not active against p-nitrophenyl-beta-D-cellobioside. High levels of activity also were observed with the disaccharides laminaribiose (1-->3), gentiobiose (1-->6), and sophorose (1-->2). Activity greater than that observed with pNPG was obtained with the flavonoids hesperetin-7-glucoside and prunin (naringenin-7-glucoside), salicin, mandelonitrile-beta-D-glucoside (a cyanogenic substrate), and sinigrin (a glucosinolate). The enzyme was not active against amygdalin, coniferin, or limonin glucoside.

Medicinal Foodstuffs. XXV. Hepatoprotective Principle and Structures of Ionone Glucoside, Phenethyl Glycoside, and Flavonol Oligoglycosides from Young Seedpods of Garden Peas, Pisum sativum L.

Abstract: A new ionone glucoside, pisumionoside, a phenethyl glycoside, sayaendoside, and two acylated flavonol oligoglycosides, pisumflavonosides I and II, were isolated from the young seedpods of garden peas, Pisum sativum L, together with quercetin and kaempferol 3-O-(6-O-trans-p-coumaroyl)-β-D-glucopyranosyl (1→2)-β-D-glucopyranosyl (1→2)-β-D-glucopyranosides and quercetin and kaempferol 3-sophorotriosides The structures of pisumionoside, sayaendoside, and pisumflavonosides I and II were determined on the basis of chemical and physicochemical evidence, respectively Quercetin 3-sophorotrioside, a principle component, was found to show protective effects on liver injury induced by D-galactosamine and lipopolysaccharide and by carbon tetrachloride in mice

A benzofuran glycoside and an acetylenic acid from the fungus Laetiporus sulphureus var. miniatus.

Abstract: A new benzofuran glycoside, masutakeside I (1) and a new C10 acetylenic acid, masutakic acid A (2) were isolated from the fruiting bodies of the fungus Laetiporus sulphureus var. miniatus. Their structures were established by spectroscopic and chemical methods. The known compounds 3-6 were also obtained and identified as egonol, demethoxyegonol, egonol glucoside and egonol gentiobioside. Some of these compounds exhibited cytotoxicity against Kato III cells.

An iridoid gentiobioside, a benzophenone glucoside and acylated flavone C-glycosides from Tripterospermum japonicum (Sieb. et Zucc.) Maxim.

Abstract: From aerial parts of Tripterospermum japonicum, 6′-O-β-D-glucopyranosylmorroniside, benzophenone glucoside, named triptephenoside and 2′′′- and 4′′′-O-acetyl-2″-O-α-L-rhamnopyranosylisovitexins were isolated, along with known iridoid and secoiridoid glucosides, and C-glycosyl flavones.

Water-soluble constituents of Glehnia littoralis fruit.

Abstract: From the water-soluble portion of the methanol extract of the fruit of Glehnia littoralis Fr SCHMIDT ex MIQ (Umbelliferae; "hamabofu" in Japanese), thirty compounds, including three new monoterpenoids and a new monoterpenoid glucoside, a new benzofuran glucoside, a new alkyl glucoside, and a new glucide, were obtained Their structures were clarified by spectral investigation

Vanillic acid 4-O-beta-D-(6'-O-galloyl) glucopyranoside and other constituents from the bark of Terminalia macroptera Guill.et Perr.

Abstract: A new phenolic glucoside gallate, vanillic acid 4-O-β-D-(6′-O-galloyl) glucopyranoside (1) was isolated from the bark of Terminalia macroptera Guill.et Perr., together with 3,3′,4′-tri-O-methylellagic acid (2) and two triterpene glucopyranosyl esters, 24-deoxy-sericoside (3) and chebuloside II (4). Compounds 2-4 not described previously for this plant, showed antimicrobial activities against Bacillus subtilis, while 3 and 4 possessed haemolytic properties. In both assays 1 was found to be inactive.

Downstream processing of enzymatically produced geranyl glucoside.

Abstract: Geraniol plays an important role in the fragrance and flavor industry. The corresponding glucoside has interesting properties as a “slow release” aroma compound. Therefore, the enzymatic production and downstream processing of geranyl glucoside were investigated. Geranyl glucoside was produced in a spray column reactor with an initial production rate of 0.58 mg U−1 h−1. A pretreated hydrophobic microfiltration membrane was used to prevent migration of the aqueous, enzyme-containing phase to the downstream process. No retention of the glucoside, which accumulated in the geraniol phase, was found. On the basis of examples from the literature, four downstream processes were tested on their viability for this system. Extraction with water and foaming were not suitable to recover geranyl glucoside from geraniol. In the first case, the glucoside selectivity for the geraniol phase was found to be high, which made extraction with water unsuccessful. In the second case it was possible to obtain a stable foam, but significant enrichment of the foam with glucoside did not occur. Adsorption on alumina and distillation under reduced pressure were applied successfully and tested in-line with the bioreactor. A maximum glucoside adsorption of 7.86 mg g−1 was achieved on alumina. After desorption and evaporation of the extractant the pure glucoside was obtained quantitatively. A pure product could not be obtained after distillation because a small amount of glucose was present in the permeate as well, which accumulated in the bottom fraction. It was shown that with this reactor system a production of 1 kg of geranyl glucoside in 2 days is possible using an initial amount of 50,000 units of enzyme.

Thioglucosidase activity from Sphingobacterium sp. strain OTG1

Abstract: Screening for novel thioglucoside hydrolase activity resulted in the isolation of Sphingobacterium sp. strain OTG1 from enrichment cultures containing octylthioglucoside (OTG). OTG was hydrolysed into octanethiol and glucose by cell free extracts. Besides thioglucoside hydrolysis, several other glucoside hydrolase activities were detected in the Sphingobacterium sp. strain OTG1 cell free extract. By adding β-glucosidase inhibitors it was possible to discriminate between these different activities. Ascorbic acid and D-gluconic acid lactone inhibited the hydrolysis of p-nitrophenyl β-glucoside, but did not affect octyl- and octylthioglucoside hydrolase activity. Besides OTG, various other thioglucosides were hydrolysed by the novel thioglucosidase, with almost the same activities regardless of the nature of the aglycone, including the myrosinase model substrate sinigrin (a glucosinolate). Sinigrin could also be used as a growth substrate by Sphingobacterium sp. strain OTG1, although at concentrations exceeding 0.15 mM degradation was not complete.

Formation of glucoside conjugates during biotransformation of dibenzofuran by Penicillium canescens SBUG-M 1139.

Abstract: Penicillium canescens oxidises dibenzofuran (DBF) to produce monohydroxylated derivatives and other more hydrophilic metabolites. These substances are water-soluble but unstable in organic solvents such as ethyl acetate, acetone or dichloromethane. Both extraction with ethyl acetate and enzymatic treatment of the aqueous culture filtrate with β-glucuronidase led to decay of the hydrophilic metabolites and indicated these products to be glycoside conjugates. The glycosyl residue was identified as glucose both by liquid chromatography and by the use of glucose oxidase. The conjugate pattern formed was the same in type and amount, independent of the carbon source used for cultivation of the fungus. Clearly, DBF transformation in P. canescens occurred in two phases: first the conversion to 2-, 3-, and 4-hydroxydibenzofuran (phase I), followed by the formation of the corresponding glucosyl conjugates (phase II). In contrast, 2,3-dihydroxydibenzofuran added to the cultures was transformed by ring cleavage producing a muconic acid-like dead-end product.