ENZYMIC QUANTIFICATION OF (1→3) (1→4)-β-D-GLUCAN IN BARLEY AND MALT

A simple and quantitative method for the determination of (1→3) (1→4)-β-D-glucan in barley flour and malt is described. The method allows direct analysis of β-glucan in flour and malt slurries. Mixed-linkage β-glucan is specifically depolymerized with a highly purified (1→3) (1→4)-β-D-glucanase (lichenase), from Bacillus subtilis, to tri-, tetra- and higher degree of polymerization (d.p.) oligosaccharides. These oligosaccharides are then specifically and quantitatively hydrolysed to glucose using purified β-D-glucosidase. The glucose is then specifically determined using glucose oxidase/peroxidase reagent. Since barley flours contain only low levels of glucose, and maltosaccharides do not interfere with the assay, removal of low d.p. sugars is not necessary. Blank values are determined for each sample allowing the direct measurement of β-glucan in maltsamples.α-Amylasedoes not interfere with the assay. The method issuitable for the routineanalysis of β-glucan in barley samples derived from breeding programs; 50 samples can be analysed by a single operator in a day. Evaluation of the technique on different days has indicated a mean standard error of 0–1 for barley flour samples containing 3–8 and 4–6% (w/w) β-glucan content.     

A new acylated and oleanane-type triterpenoid saponin from Gypsophila arrostii roots

A new acylated and triterpenoidal saponin, named GS1, was isolated from the roots of Gypsophila arrostii Guss. On the basis of acid hydrolysis, comprehensive spectroscopic analyses and comparison with spectral data of known compounds, its structure was established as 3-O-β-D-xylopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-{21-O-[(E)-3,4,5trimethoxycinnamoyl]}21-hydroxygypsogenin 28-O-β-D-glucopyranosyl-(1→2)- [β-D-arabinopyranosyl-(1→3)]-β-D-xylopyranosyl-(1→3]-α-L-rhamnopyranosyl ester. This article deals with the isolation and structural elucidation of new acylated and oleanane-type saponin.     

An Antifungal Saponin from White Asparagus ( Asparagus officinalis L) Bottoms

An antifungal saponin was isolated from the bottom cut of white asparagus (Asparagus officinalis L), which is unusable in food processing. The structure of the saponin was identified as 3-O-[{α-L -rhamnopyranosyl (1→2)} {α-L -rhamnopyranosyl (1→4)}-β-D -glucopyranosyl] (25S) spirost-5-ene-3β-ol from chemical and spectral data. This saponin was shown to be identical with collettinside III from Dioscorea collettii, and to inhibit the growth of some kinds of fungi at μg ml⁻¹ levels.     

Oligosaccharide structures formed during the hydrolysis of lactose by Aspergillus oryzae β-galactosidase

Di-, tri-, tetra-, penta- and hexasaccharides were formed during the hydrolysis of lactose by transgalactosylation reaction of Aspergillus oryzae β-galactosidase. In this study the isolation and characterization of the major constituents of tri-, tetra- and pentasaccharides are described. The structure elucidation of 3 tri-, 2 tetra- and 1 pentasaccharides was carried out by methylation analysis, mass spectrometry and ¹³C-nmr spectrometry. The trisaccharides are $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}\text{(3′-}\text{galactosyl-lactose}\text{)}$, $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}\text{(6′-}\text{galactosyl-lactose}\text{)}$ and $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-O-[β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)]-}\text{d}\text{-}\text{glucose}\text{(4,6-}\text{digalactosyl-glucose}\text{)}$. Tetrasaccharides are $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$ and $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)}$ [or $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)]-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$. Pentasaccharide is $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$.     

UVC dosage effects on the physico-chemical properties of lime (Citrus aurantifolia) juice

A phenyl lipid alkaloid and seven phenolic compounds were isolated from the aerial part of Spergularia marina, a halophyte that grows on salt marshes and tidal flat. These compounds were identified as 2,4-di-tert-butylphenol, N-hexacosanoylanthranilic acid, tryptophan, 4-hydroxybenzyol glucopyranoside, luteolin 6-C-β-D-glucopyranoside 8-C-β-D-(2-O-feruloyl)glucopyranoside, luteolin 6-C-β-D-(2-O-feruloyl)glucopyranoside 8-C-β-D-glucopyranoside, apigenin 6-C-β-D-glucopyranoside 8-C-β-D-(2-O-feruloyl)glucopyranoside, and apigenin 6-C-β-D-(2-O-feruloyl)glucopyranoside 8-C-β-D-glucopyranoside. The structures were determined by nuclear magnetic resonance and electrospray ionization-mass spectroscopy.     

Isolation and structural determination of a novel flavonol triglycoside and 7 compounds from the leaves of oriental raisin tree (Hovenia dulcis) and their antioxidative activity

The hot water and ethanol extracts of oriental raisin tree (Hovenia dulcis Thunb) leaves showed DPPH radical scavenging activities. Antioxidants were purified and isolated from hot water and ethanol extracts by various column chromatographic procedures with the guided assay of DPPH radical scavenging. The structure of a novel flavonol triglycoside was determined to kaempferol 3-O-α-l-rhamnopyranoside-7-O-[α-d-glucopyranosyl(1→3)-α-l-rhamnopyranoside] (4). In addition, 7 known compounds were identified as caffeine (1), kaempferol 3,7-O-α-l-dirhamnopyranoside (2), kaempferol 3-O-α-l-rhamnopyranosyl( 1→6)-O-β-d-glucopyranosyl(1→2)-O-β-d-glucopyranoside (3), E-3-carboxy-2-petenedioate 5-methyl ester (5), quercetin 3-O-α-l-rhamnopyranoside (6), kaempferol 3-O-α-l-rhamnopyranoside (7), and quercetin 3-O-β-d-glucopyranoside (8). Compound 1–3 and 5–8 were newly identified in this plant. Quercetin glycosides (5, 7) showed higher DPPH radical scavenging activity than other compounds.     

Seed oil of white star apple (Chrysophyllum albidum)—physicochemical characteristics and fatty acid composition

Quercetin and kaempferol rhamnodiglucosides are characteristic compounds of Camellia sinensis. Their structures were determined as quercetin-and kaempferol-3-O-[β-D -glucopyranosyl-(1 → 3)-α-L -rhamnopyranosyl-(1 → 6)-β-D -glucopyranosides]. Reversed phase HPLC methods for preparative isolation and analytical separation of both compounds were developed. The structural elucidation of the compounds by means of NMR spectroscopy, fast atom bombardment MS and GC-MS of the sugar moieties is described. Black tea contains 0–0·95 g kg^?1 quercetin rhamnodiglucoside and 0·05–1·25 g kg^?1 kaempferol rhamnodiglucoside.     

Antidiabetic and anti-inflammatory potential of sulphated polygalactans from red seaweeds Kappaphycus alvarezii and Gracilaria opuntia

Antidiabetic and anti-inflammatory potential of sulphated polygalactans isolated from the red seaweeds Kappaphycus alvarezii and Gracilaria opuntia were acquired by employing different in vitro systems. The sulphated galactopyran motif derived from G. opuntia possessed significant antidiabetic properties as identified by α-amylase (IC₅₀ 0.04 mg/mL), α-glucosidase (IC₅₀ 0.09 mg/mL) and dipeptidyl peptidase-4 (DPP-4, IC₅₀ 0.09 mg/mL) inhibitory activities. Based on the detailed nuclear magnetic resonance spectroscopy experiments the sulphated galactopyran motif of G. opuntia was designated as →3)-4-O-sulfonato-(6-O-acetyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-sulfonato)-α-D-galactopyranosyl-(1→3)-4-O-sulfonato-(6-O-acetyl)-β-D-xylosyl-(1→3)-4-O-sulfonato-(6-O-acetyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-sulfonato)-α-D-galactopyranan, while the one from K. alvarezii was demonstrated to be →4)-4-O-sulfonato-(2-O-methyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-methyl)-α-D-galactopyranan. The sulphated galactans from G. opuntia showed greater anti-inflammatory inhibitory activities as determined by cyclooxygenase-1 (COX-1, IC₅₀ 0.01 mg/mL), cyclooxygenase-2 (COX-2, IC₅₀ 0.03 mg/mL), and 5-lipoxygenase inhibitory activities (5-LOX, IC₅₀ 0.24 mg/mL). This study revealed that the sulfated polygalactan enriched concentrate from G. opuntia can be used as potential therapeutic candidate to suppress the hyperglycemic response in diabetic conditions and inflammatory activity. They can be used to develop functional food ingredient in nutraceutical products.     

Purification, chemical characterization, and antioxidant activity of a polysaccharide from the fruiting bodies of sanghuang mushroom (Phellinus baumii Pilát)

A purified water-soluble polysaccharide was isolated from the fruiting bodies of sanghuang mushroom (Phellinus baumii Pilát) using hot water extraction, DEAE Sepharose Fast Flow anion exchange and High-Resolution Sephacryl S-1000 gel-filtration chromatography. The purified polysaccharide was a complex β-d-glucan, with a molecular mass of 230 kDa. Fourier-transform infrared (FT-IR), methylation analysis, and NMR spectroscopy of sanghuang mushroom polysaccharide (PBF3) indicated that the polysaccharide contained (1→3)-β-d-, (1→4)-β-d-, and branched (1→3,6)-β-d-glucopyranosyl residues. On the basis of hydroxyl radical assay, superoxide radical assay, and DPPH radical assay, its antioxidant activities were investigated. PBF3 had significant effect on scavenging hydroxyl radicals, an equivalent inhibiting ability to vitamin C on superoxide radical, and a little lower scavenging activity on DPPH radical than vitamin C, and should be explored as a novel potential antioxidant.     

Analysis of β-glucans and chitin in a Saccharomyces cerevisiae cell wall mutant using high-performance liquid chromatography

We have previously shown that mutations in the yeast KNR4 gene resulted in pleiotropic cell wall defects, including resistance to killer 9 toxin, elevated osmotic sensitivity to SDS and increased resistance to zymolyase, a (1→3)-β-glucanase. In this report, we further demonstrated that knr4 mutant cells were more permeable to a chromogenic substrate, X-GAL, suggesting that the mutant cell walls were leakier to certain non-permeable molecules. To determine if these defects resulted from structural changes in the cell walls, we analysed the alkali-insoluble cell wall components using HPLC assays developed for this purpose. Comparative analysis using four isogenic strains from a ‘knr4 disrupted’ tetrad demonstrated that mutant cell walls contained much less (1→3)-β-glucan and (1→6)-β-glucan; however, the level of chitin, a minor cell wall component, was found to be five times higher in the mutant strains compared to the wild-type strains. The data suggested that the knr4 mutant cell walls were dramatically weakened, which may explain the pleiotropic cell wall defects.     

Coumaroyl quinic acid derivatives and flavonoids from immature pear (Pyrus pyrifolia nakai) fruit

Fourteen compounds were isolated from 60% ethanol extracts of immature pear (Pyrus pyrifolia Nakai cv. Chuhwangbae) fruit using Amberlite XAD-2 column HPLC with guided DPPH radical scavenging assay. Based on MS and NMR analysis, the isolated compounds were identified as 5-O-trans-caffeoyl quinic acid methyl ester (1), malaxinic acid (2), 5-O-trans-p-coumaroyl quinic acid methyl ester (3), 5-O-cis-p-coumaroyl quinic acid methyl ester (4), 5-O-trans-p-coumaroyl quinic acid (5), trans-p-coumaric acid (6), methyl cis-p-coumarate (7), methyl trans-p-coumarate (8), 3,5-O-dicaffeoyl quinic acid (9), (-)-epicatechin (10), (S)-(+)-2-cis-abscisic acid (11), isorhamnetin 3-O-β-d-galacto-pyranoside (12), isorhamnetin-3-O-β-d-glucopyranoside (13), and isorhamnetin 3-O-α-l-rhamnopyranosyl (1→6)-O-β-d-glucopyranoside (14). Six compounds (1, 2, 6, 9, 10, and 13) were identified previously, but other compounds (3–5, 7, 8, 11, 12, and 14) were isolated for the first time from pear.     

Chemical characterisation of anthocyanins in tamarillo (Solanum betaceum Cav.) and Andes berry (Rubus glaucus Benth.) fruits

The anthocyanin composition of tamarillo (Solanum betaceum Cav., red variety) and Andes berry (Rubus glaucus Benth.) was determined by HPLC–PDA and HPLC–ESIMS. From the anthocyanin-rich extracts (AREs), pure compounds (1–7) were obtained by MLCCC (multilayer countercurrent chromatography) and further preparative HPLC, and their unequivocal structures were obtained by 1D and 2D NMR analyses. The new anthocyanin delphinidin 3-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside-3′-O-β-d-glucopyranoside, as well as the known cyanidin-3-O-rutinoside, pelargonidin-3-O-rutinoside, and delphinidin-3-O-rutinoside were identified as constituents of tamarillo fruit. Although the anthocyanin composition of Andes berry had been reported before in the literature, the unequivocal structure elucidation of the major compound, cyanidin-3-O-α-l-rhamnopyranosyl-(1 → 6)-O-β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranoside, was achieved for the first time.     

Novel acetylated flavonoid glycosides from the leaves of Allium ursinum

Seven flavonoid glycosides, kaempferol 3-O-α-L-rhamnopyranosyl (1→2)-[3-O-acetyl]-β-D-glucopyranoside (1), kaempferol 3-O-α-L-rhamnopyronosyl (1→2)-[6-O-acetyl]-β-D-glucopyranoside (2), kaempferol 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (3), kaempferol 3-O-β-D-glucopyranoside (4), kaempferol 3,7-di-O-β-D-glucopyranoside (5), 7-O-β-D-glucopyranosyl kaempferol 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (6), kaempferol 3-O-α-L-rhamnopyranosyl (1→2)-β-D-glucopyranoside-7-O-[2-O-(trans-p-coumaroyl)]-β-D-glucopyranoside (7) were isolated from the n-butanol fraction of Allium ursinum L. and the structures of these compounds were elucidated on the basis of mass spectrometry, ¹H NMR, ¹³C NMR, HMQC and HMBC data. Among them, 1 and 2 are novel compounds and compounds 4 and 5 were isolated from this plant species for the first time.     

Furostanol saponins in Allium caepa L. Var. tropeana seeds

An analysis of the polar extracts from seeds of Allium caepa L. var. tropeana led to the isolation of eight furostanol saponins, one of which was previously reported in the literature. On the basis of 1D, 2D NMR and mass spectrometry data, the structures of the compounds were elucidated as 1-O-β-D-glucopyranosyl-(25R)-furost-5(6)-en-1β,3β,22α,26-tetraol-26-O-α-L-rhamnopyranosyl-(1‴ → 2″)-O-α-L-arabinopyranoside (1a), its epimer at position 22, 1-O-β-D-glucopyranosyl-(25R)-furost-5(6)-en-1β,3β,22β,26-tetraol-26-O-α-L-rhamnopyranosyl-(1‴ → 2″)-O-α-L-arabinopyranoside (1b), 1-O-β-D-glucopyranosyl-22-O-methyl-(25R)-furost-5(6)-en-1β,3β,22ξ,26-tetraol-26-O-α-L-rhamnopyranosyl-(1‴ → 2″)-O-α-L-arabinopyranoside (probably artefact) (2), 1-O-β-D-glucopyranosyl-(25R)-furost-5(6)-en-1β,3β,22β,26-tetraol-26-O-α-L-rhamnopyranosyl-(1‴ → 6″)-O-β-D-galactopyranoside (3), 1-O-β-D-glucopyranosyl-22-O-methyl-(25R)-furost-5(6)-en-1β,3β,22ξ,26-tetraol-26-O-α-L-rhamnopyranosyl-(1‴ → 6″)-O-β-D-galactopyranoside (probably artefact) (4), 26-O-β-D-glucopyranosyl-(25R)-furost-5(6)-en-3β,22α,26-triol-3-O-α-L-rhamnopyranosyl-(1″ → 2′)-O-[β-D-glucopyranosyl-(1‴ → 6′)-O]-β-D-glucopyranoside (5a) and its epimer at position 22,26-O-β-D-glucopyranosyl-(25R)-furost-5(6)-en-3β,22β,26-triol-3-O-α-L-rhamnopyranosyl-(1″ → 2′)-O-[β-D-glucopyranosyl-(1‴ → 6′)-O]-β-D-glucopyranoside (5b) and the known compound 26-O-β-D-glucopyranosyl-22-O-methyl-(25R)-furost-5(6)-en-3β,22ξ,26-triol-3-O-α-L-rhamnopyranosyl-(1″ → 2′)-O-[β-D-glucopyranosyl-(1‴ → 6′)-O]-β-D-glucopyranoside (6) [Mimaki, Y., Satou, T., Kuroda, M., Sashida, Y., & Hatakeyama, Y. (1999). Steroidal saponins from the bulbs of Lilium candidum. Phytochemistry, 51, 567–573]. This is the first report on furostanol saponins in the seeds of Allium caepa L. var. tropeana.     

Hydrolysis and Fermentation by Rat Gut Microorganisms of 2-O-β-D-Xylopyranosyl (5-O-Feruloyl)-L-Arabinose Derived from Grass Cell Wall Arabinoxylan

It has been shown that a common side-chain of grass cell wall arabinoxylans is 2-O-β-D -xylopyranosyl-(5-O-feruloyl)-L -arabinose [X(F)A]. The stability of X(F)A was determined by incubation of (feruloyl-U-¹⁴C)-labelled X(F)A and (pentosyl-1-³H)-labelled X(F)A anaerobically with rat caecal contents and chromatographic analysis of the radioactive products. The ester linkage was hydrolysed very rapidly to form ferulic acid (which was stable) and the disaccharide (XA). The ³H-XA was further metabolised, but ³H-monosaccharides did not accumulate. In the end-products of fermentation of (pentosyl-³H)-labelled X(F)A, 67% of the ³H was present in bacterial polymers. In contrast, when free [1-³H]arabinose was incubated with rat caecal contents, 74% of the ³H quickly became volatile, probably as ³H₂O. It is concluded that X(F)A is highly susceptible to (feruloyl)esterase activity produced by bacteria present in the rat caecum, and that the disaccharide produced is further fermented, but not via the production of extracellular arabinose and xylose. © 1997 SCI.     

Linalool disaccharides as flavour precursors from green coffee beans (<Emphasis Type="Italic">Coffea arabica</Emphasis>)

Two linalool disaccharides, isolated from green coffee beans (Coffea arabica), were identified as 3(S)-linalool-3-O-#-D-glucopyranosyl-#-D-apiofuranoside and 3(S)-linalool-3-O-#-D-glucopyranosyl-!-L-arabinopyranoside. The structures were established by one- and two-dimensional ¹H and ¹³C NMR spectra as well as by ESI MS/MS spectra.     

Isolation and identification of compounds from the ethanolic extract of flowers of the tea (Camellia sinensis) plant and their contribution to the antioxidant capacity

While beneficial health properties of tea leaves have been extensively studied, less attention has been given to that of flowers of the tea (Camellia sinensis) plant. In this work, the ethanolic extract and its ethyl acetate-soluble fraction (EEA) from the tea flowers were found to possess the potent antioxidant activity using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay. The compounds present in EEA had comparatively strong DPPH scavenging activity and strongly contributed to the antioxidant activity of the tea flowers. From EEA, besides eight catechins, five flavonol glycosides were isolated and their structures were elucidated on the basis of mass spectrometry and nuclear magnetic resonance spectroscopy as myricetin 3-O-β-d-galactopyranoside, quercetin 3-O-β-d-galactopyranoside, kaempferol 3-O-β-d-galactopyranoside, kaempferol 3-O-β-d-glucopyranoside, and kaempferol 3-O-[α-l-rhamnopyranosyl-(1-6)-β-d-glucopyranoside]. In addition, epigallocatechin gallate and epicatechin gallate were found as the major active components responsible for the antioxidant activity of tea flowers through the use of a combination of preparative liquid chromatography separation and DPPH assay.     

Flavonoid glycosides from Pouteria obovata (R. Br.) fruit flour

Three unknown dihydroflavanol glycosides: 2R,3R-4′O-methyl dihydrokaempferol 7-O-[3″-O-acetyl]-β-d-glucopyranoside (1), 2R,3R-4′-O-methyl dihydrokaempferol 7-O-β-d-β-l-xylopyranosyl-(1″′ → 6″)-[3″-O-acetyl]-β-d-glucopyranoside (2), 2R,3R-4′-O-methyl dihydrokaempferol 3-O-β-d-β-l-xylopyranosyl-(1″′ → 6″)-[3″-O-acetyl]-β-d-glucopyranoside (3), together with gallic acid (4) were isolated from the n-butanol fraction of Pouteria obovata fruit flour by chromatographic methods and their structures were elucidated on the basis of CD, UV, MS, monodimensional NMR (¹H and ¹³C) and bidimensional NMR (COSY, HSQC and HMBC). The quantitative analysis of flavonoids and phenols were also reported. Total phenolic amount (51.1 ± 14.1 mg GAE/1000 g; p < 0.0006) and flavonoid content (153.2 ± 3.5 mg CE/100 g; p < 0.004) were detected spectrophotometrically.     

Flavonol glycosides from whole cottonseed by-product

Cottonseeds are fed to high-producing dairy cows as a source of fat and highly-digestible fibre. Seven flavonol glycosides have been identified from whole cottonseed by-product. Their structures were established as quercetin 3-O-{β-d-apiofuranosyl-(1 → 2)-[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside} (1), kaempferol 3-O-{β-d-apiofuranosyl-(1 → 2)-[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside} (2), quercetin 3-O-[β-d-apiofuranosyl-(1 → 2)-β-d-glucopyranoside] (3), quercetin 3-O-β-d-glucopyranoside (4), kaempferol 3-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside] (5), quercetin 3-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside] (6), and kaempferol 3-O-α-l-rhamnopyranoside (7). Gallic acid (8) and 3,4-dihydroxybenzoic acid (9) were also found. All structures were elucidated by ESI-MS and NMR spectroscopic methods. Total polyphenols were assayed by the Folin–Ciocalteu method.     

Selective utilization of gluco-oligosaccharides by lactobacilli: A mechanism study revealing the impact of glycosidic linkages and degree of polymerization on their utilization

Gluco-oligosaccharides (GlcOS) are potential prebiotics that positively modulate beneficial gut commensals like lactobacilli. For the rational design of GlcOS as prebiotics or combined with lactobacilli as synbiotics, it is important to establish the structure requirements of GlcOS and specificity toward lactobacilli. Herein, the utilization of 10 GlcOS with varied degrees of polymerization (DP) and glycosidic linkages by 7 lactobacilli strains (Levilactobacillus brevis ATCC 8287, Limosilactobacillus reuteri ATCC PTA 6475, Lacticaseibacillus rhamnosus ATCC 53103, Lentilactobacillus buchneri ATCC 4005, Limosilactobacillus fermentum FUA 3589, Lactiplantibacillus plantarum WCFS1, and Lactobacillus gasseri ATCC 33323) was studied. L. brevis ATCC 8287 was the only strain that grew on α/β-(1→4/6) linked disaccharides, whereas other strains showed diverse patterns, dependent on the availability of genes encoding sugar transporters and catabolic enzymes. The effect of DP on GlcOS utilization was strain dependent. β-(1→4) Linked cello-oligosaccharides (COS) supported the growth of L. brevis ATCC 8287 and L. plantarum WCFS1, and shorter COS (DP 2–3) were preferentially utilized over longer COS (DP 4–7) (consumption ≥90% vs. 40%–60%). α-(1→4) Linked maltotriose and maltodextrin (DP 2–11) were effectively utilized by L. brevis ATCC 8287, L. reuteri ATCC 6475, and L. plantarum WCFS1, but not L. fermentum FUA 3589. Growth of L. brevis ATCC 8287 on branched isomalto-oligosaccharides (DP 2–6) suggested preferential consumption of DP 2–3, but no preference between α-(1→6) and α-(1→4) linkages. The knowledge of the structure-specific GlcOS utilization by different lactobacilli from this study helps the structural rationale of GlcOS for prebiotic development.