Structural features of the polysaccharide gum from Acacia glomerosa

Acacia glomerosa, Benth. (Vulgares Series) exudates a clear gum which produces gels easily. The physico-chemical data and sugar composition are very close to gum arabic from Acacia senegal, except that A. glomerosa gum contains a high nitrogen content. A series of degraded products was prepared by acid hydrolysis and Smith-degradation. The characterization of the degraded products by partial hydrolysis, sugar composition and by the application of uni- and bidimensional spectroscopy led to know interesting structural features of the polysaccharide isolated from A. glomerosa gum. This polysaccharide, as that from A. senegal gum, consists of 1,3-β- -galactopyranosyl backbone. There are side-chains of 1,3-β- -galactopyranosyl oligosaccharides attached to position six of the galactan main chain. Arabinose (furanosyl and pyranosyl) residues may be up to four units long because it was necessary to prepare four polysaccharides to remove them from the gum structure. Uronic acid residues were difficult to remove as has been observed in other Acacia gums.     

Terpenoids from Stinking toe (Hymneae courbaril) fruits with cyclooxygenase and lipid peroxidation inhibitory activities

Stinking toe (Hymenaea courbaril), also called Jatoba and Kerosene tree, is a medicinal plant commonly found in the central and South American countries. In the Caribbean, Mexico and Brazil, the powdery sweet dust of its fruit is consumed for energy. The chemical examination of the yellowish sweet powder of the fruit yielded sucrose and linolenic acid as major compounds. The pods yielded the labdane diterpenoids crotomachlin (1), labd-13E-en-8-ol-15-oic acid (2), labdanolic acid (4), (13E)-labda 7, 13 dien-15-oic acid (5) and labd-8 (17), 13E- dien-15-oic acid (6), along with the sesquiterpene, spathulenol (7), as confirmed by ¹H and ¹³C NMR spectral studies. The methyl ester of labd-13E-en-8-ol-15-oic acid (3) was also characterized during the purification of compound 5. The total amount of these terpenoids in the fruit was about 0.1% (w/w) of the dried fruit. Compounds 1–5 and 7 were assayed for anti-inflammatory activity using cyclooxygenase-1 (COX-1) and -2 (COX-2) enzymes. At 100 ppm, compounds 3 and 4 showed selective COX-2 enzyme inhibition. Also, compounds 1, 2 and 5 inhibited lipid peroxidation by 46%, 48% and 75%, respectively, at 100 ppm. These compounds were isolated from this fruit and their COX and lipid peroxidation inhibitory activities are reported for the first time in this paper.     

Structural investigation of a novel fucoglucogalactan isolated from the fruiting bodies of the fungus Hericium erinaceus

A new heteropolysaccharide with a molecular weight of 1.94 × 10⁴ Da, HEPF1, was isolated from the fruiting bodies of Hericium erinaceus. It is composed of fucose, galactose and glucose in the ratio of 1:4:1, as well as a minor proportion of 3-O-methyl rhamnose. Sugar analyses, methylation analysis, together with ¹H and ¹³C NMR spectroscopy established that HEPF1 has a (1 → 6)-linked α-d-galactopyranosyl backbone with branches that are composed of fucose attached to O-2; it also contains 6-O-substituted-β-d-oligoglucosyl units and a minor terminal 3-O-methyl rhamnose residue.     

Extraction and physicochemical characterisation of polysaccharide gum from Yanang (Tiliacora triandra) leaves

Yanang (Tiliacora triandra) is a vegetable used in many cuisines of the northeast of Thailand and Lao People’s Democratic Republic. This paper reports the optimised extraction and some physicochemical characteristics of polysaccharide gum from Yanang leaves. The optimised extraction condition was at the leaf:water ratio of 1:6.6, 85 °C, and 100 min extraction time. The major monosaccharide constituent of Yanang gum was xylose, together with substantial amounts of other neutral sugars. The FT-IR spectra of Yanang gum were similar to that of xylan. Yanang gum exhibited shear-thinning flow behaviour and the extent of shear-thinning was concentration dependent. The mechanical spectra of Yanang gum at low concentration (0.5%) were typical of semi-diluted to concentrated solutions. However, with increasing concentration, the solution behaved like a weak gel.     

Analytical data for Acacia senegal var. senegal gum samples collected between 1993 and 1995 from Sudan

Over 1500 authentic and commercial A. senegal var. senegal gum samples were analysed to evaluate existing quality control parameters and to assess the potential of new parameters such as pH, viscosity, viscosity average molecular weight (M_V) equivalent weight and total uronic acid content as additional qualifying indices. The data obtained indicate the following mean values: moisture (10.75%), ash (3.77%), nitrogen (0.328%), specific rotation (−31.3°), pH (4.66), equivalent weight (1436) and total uronic acid content (13.71%). The results also indicate wide variations in intrinsic viscosity and viscosity average molecular weight (mean values 16.4 ml g⁻¹ and 9.0×10⁵, respectively. Accordingly these parameters, therefore, cannot be recommended as qualifying indices.     

Comparison of antimicrobial resistance in Salmonella and Campylobacter isolated from turkeys in the Midwest USA

The current study was carried out to determine the antimicrobial resistance profiles and evaluate some molecular characteristics of a set of Salmonella and Campylobacter isolates recovered from production line turkeys in the Midwest region of the United States. A total of 94 birds identified as being positive for both Salmonella and Campylobacter spp. were selected for study. All Salmonella isolates were examined for antimicrobial resistance using the methods employed in the National Antimicrobial Resistance Monitoring System (NARMS). Campylobacter isolates were subjected to similar analysis using the Etest^®. In addition, polymerase chain reaction (PCR) was carried out to determine the presence of the antimicrobial resistance associated genes, integrase (int1), class 1 integrons (Salmonella and Campylobacter) and a multidrug efflux pump (Campylobacter spp.). Results from the study showed that the Salmonella and Campylobacter isolates examined displayed resistance to a number of antimicrobials, with Salmonella and Campylobacter isolates being resistant to at least three antimicrobials while some isolates showed resistances to 6 or 8 different antimicrobials. In addition, 68.1% of the Salmonella isolates tested were found to be positive for the class I integrase gene (int1), 28.7% possessed a 1000 bp gene cassette and 17% possessed an 800 bp gene cassette. All Campylobacter isolates were negative for int1, but 36.2% tested positive for the Campylobacter multidrug efflux pump (CmeB). A considerable number of Salmonella and Campylobacter isolates tested displayed varying degrees of antimicrobial resistance as well as the presence of some factors associated with the carriage and persistence of antimicrobial resistance. Similarities in the types of antimicrobial resistance observed in Campylobacter and Salmonella strains was evident. The results of this study suggest that prescribing practice at the farm level may be a factor in promoting antimicrobial resistance in more than one species of organism. Such practices may, therefore, contribute to the potential health risk for consumers should micro-organisms carrying multiple antimicrobial resistances enter the food chain. This study may be one of the first to report on the incidence of the multidrug efflux pump (CmeB) in Campylobacters recovered from processed turkeys. The antimicrobial resistance and molecular characteristics of Salmonella and Campylobacter is discussed.     

Anti-diabetic effects of polysaccharides from Opuntia monacantha cladode in normal and streptozotocin-induced diabetic rats

Opuntia was widely known for its use in herbal medicines to treat many diseases. In this work, the polysaccharides of Opuntia monacantha cladode (POMC) were extracted by distilled water and classified by ethanol solution with different concentrations. POMC could decrease the daily water consumption in streptozotocin-induced diabetic rats comparable to dimethylbiguanide, a commercial anti-diabetic drug. An increase to food intake was also shown for streptozotocin-induced diabetic rats administered by POMC. By determination of blood glucose (BG), total cholesterol (TC), total triglyceride (TG) and high density lipoprotein cholesterol (HDL) levels, it revealed that POMC had beneficial effects on the improvement in the control of blood glucose and serum lipid level. Daily treatment with 100–300 mg/kg body weight of POMC for four weeks not only brought a significant decrease on blood glucose level in streptozotocin-induced diabetic rats, but also enhanced the cardioprotective lipid HDL level (P < 0.05). The insulin level in streptozotocin-induced diabetic rats was not significantly affected by POMC and dimethylbiguanide treatment (P > 0.05). The mechanism of POMC's hypoglycemic action might be similar to that of dimethylbiguanide.

Industrial relevance

Opuntia cladode has been used traditionally as a herbal medicine for treating diabetes, burns, bronchial asthma and indigestion in many countries over the world. Polysaccharides in it might be responsible for these beneficial properties. In the present study, polysaccharides were prepared from Opuntia cladode and their hypoglycemic effects were determined. The results indicated that this polysaccharides could improve the control in blood glucose and serum lipid levels of streptozotocin-induced diabetic rats. This conclusion would be helpful for further developing this traditional medicinal herb.     

Structural characterisation and antimutagenic activity of a novel polysaccharide isolated from Sepiella maindroni ink

A new heteropolysaccharide, named as SIP, was isolated from the ink of cuttlefish, Sepiella maindroni, by enzymolysis, anion-exchange and gel-permeation chromatography and tested for its antimutagenic activity. It was homogeneous with a molecular weight of 1.13 × 10⁴ Da by HPSEC–MALLS analysis. SIP contained glucuronic acid, mannose, N-acetylgalactosamine, and fucose in a molar ratio of 1:1:2:2. Its structural characteristics were investigated and elucidated by methylation analysis, GLC–MS, and NMR (¹H, ¹³C, H–H COSY, HMQC, HMBC, TOCSY and NOESY). The hexasaccharide repeating unit of SIP was found to be a backbone composed of fucose, N-acetylgalactosamine and mannose in a molar ratio of 2:2:1, and with a single branch of glucuronic acid at the C-3 position of mannose. According to the micronucleus test, SIP could significantly reduce the frequency of micronucleated cells in polychromatic erythrocytes and reticulocytes induced by cyclophosphamide in tumor-bearing mice, which revealed that SIP presented strong antimutagenic activity.     

Structural characterization and antioxidant activity of an extracellular polysaccharide isolated from Brevibacterium otitidis BTS 44

A water-soluble acidic extracellular polysaccharide reaching a maximum concentration of 23.4 g/l growth medium, coded as BSMA, was isolated from the non-pathogenic soil bacteria Brevibacterium otitidis BTS44, by precipitating with two volumes of ethanol. BSMA consisted of arabinose, mannose, glucose and mannouronic acid in ratios of 2.7:3.6:2.1:1.0. No protein was detected in the BSMA fraction, and its molecular weight was about 127 kDa. It has a backbone composed of (1 → 5)-linked arabinose, (1 → 6)-linked mannose with three branches attached to O-3 of (1 → 6)-linked mannose and terminated with either mannose, or mannose and glucose; all the glucose and most of the mannouronic acid are distributed in branches. Partial acid hydrolysis of BSMA gave four sub-fractions termed BSMA-1, BSMA-2, BSMA-3 and BSMA-4. BSMA-1 was composed of arabinose, mannose and trace amounts of mannouronic acid; BSMA-2 was only composed of arabinose and mannose; BSMA-3 was composed of mannose, mannouronic acid and glucose, and BSMA-4 was only composed of mannose and glucose. In the in vitro antioxidant assay, BSMA was found to possess DPPH radical-scavenging activity, with an IC₅₀ value of 120 μg/ml.     

Structural characterisation of a heteropolysaccharide by NMR spectra

An undocumented water-soluble polysaccharide, LZ-C-1, was isolated from the fruiting bodies of the fungus, Ganoderma lucidum. The polysaccharide had a molecular weight of 7 × 10³ Da, and was mainly composed of l-Fuc, d-Glc and d-Gal. LZ-C-1 had a sugar content of ∼96.4% as measured using the phenol–sulphuric acid method. As a precondition to understand the bioactivity, structural features of LZ-C-1 were investigated by a combination of total hydrolysis, methylation analysis, FT-IR and NMR studies. The results indicated that LZ-C-1 had a backbone of 1,6-disubstituted-α-galactopyranosyl, 1,2,6-trisubstituted-α-galactopyranosyl, 1,3-disubstituted-β-glucopyranosyl and 1,4,6-trisubstituted-β-glucopyranosyl residues. The branches were mainly composed of 1-substituted-β-glucopyranosyl and 1-substituted-α-fucopyranosyl residues.     

Effect of a global regulatory gene, afsR2, from Streptomyces lividans on avermectin production in Streptomyces avermitilis

The global regulatory gene, afsR2, from Streptomyces lividans was previously reported to highly stimulate two structurally unrelated antibiotics, actinorhodin and undecylprodigiosin, in both S. lividans and its close relative S. coelicolor. Production of eight avermectin components was also improved in S. avermitilis: the use of wild-type S. avermitilis and its high-producing mutant, transformed by introduction of multiple copies of afsR2, increased the total avermectin productions by 2.3-fold and 1.5-fold, respectively.     

Structural characteristics of water-soluble polysaccharides from Rabdosia serra (MAXIM.) HARA leaf and stem and their antioxidant capacities

Water-soluble polysaccharides of Rabdosia serra leaf and stem were fractionated by ultrafiltration and DEAE-Sepharose fast flow chromatogram to obtain water (RSLP-I and RSSP-I), 0.1M NaCl (RSLP-II and RSSP-II) and 0.2M NaCl (RSLP-III and RSSP-III) eluates. Their molecular weights were determined by high performance gel permeation chromatography. Monosaccharide composition analysis indicated that the water eluates comprised of rhamnose, arabinose, xylose, mannose, glucose and galactose. The ascending percentage of galactose and descending percentage of glucose in the eluates were observed with the increase of NaCl concentration. The branched RSLP-I and RSSP-I were composed mainly of →6)-Glcp-(1→, →6)-Galp-(1→, and →5)-Araf-(1→ residues with the ratio of 15.0:4.2:3.8 and 5.5:6.4:3.5, respectively. However, a low level of 1,6-linked glucosyl was observed in RSLP-II, RSSP-II, RSLP-III and RSSP-III. The structural characteristics were further analysed by infrared spectrophotometry. The purified leaf and stem polysaccharides possessed moderate antioxidant capacities.     

Pathogenic Yersinia enterocolitica 2/O:9 and Yersinia pseudotuberculosis 1/O:1 strains isolated from human and non-human sources in the Plateau State of Nigeria

Foodborne yersiniosis, caused by enteropathogenic Yersinia, especially Yersinia enterocolitica, is an important cause of diarrhea in developed countries, especially in temperate zones. Since studies concerning the presence of enteropathogenic Yersinia in humans and foods are rare in developing countries and tropical areas, human and non-human samples were studied in Plateau state of Nigeria to obtain information on the epidemiology of Y. enterocolitica and Yersinia pseudotuberculosis. Surprisingly, ail-positive Y. enterocolitica and inv-positive Y. pseudotuberculosis were isolated in Plateau state of Nigeria from several samples of human and non-human origin. Bioserotype 1/O:1 was the only Y. pseudotuberculosis type found. Y. enterocolitica belonging to bioserotype 2/O:9 was the dominating type found in most samples. Bioserotype 4/O:3 was isolated only from one pig and one sheep. Using PFGE, 5 genotypes were obtained among 45 Y. enterocolitica 2/O:9 strains with NotI, ApaI and XhoI enzymes and 3 among 20 Y. pseudotuberculosis 1/O:1 strains with NotI and SpeI enzymes. All human Y. pseudotuberculosis 1/O:1 strains were indistinguishable from pig, sheep or food strains. The dominating genotype of Y. enterocolitica 2/O:9 strains among humans was also found among strains isolated from pig, fermented cow milk and traditional intestine pepper soap samples.     

Antioxidant activity of 1,3-dicaffeoylquinic acid isolated from Inula viscosa

Inula viscosa is a perennial herbaceous plant used topically in folk medicine as an anti-scabies, anti-inflammatory, and wound-healing agent. We examined the antioxidant activity of the methanolic extract of I. viscosa. We isolated and identified several polyphenolic antioxidants from I. viscosa leaves and focused on 1,3-dicaffeoylquinic acid (1,3-diCQA). Antioxidant activity was measured using ABTS and DPPH assays, which measure antioxidant activity. The concentrations of 1,3-diCQA required for the inhibition of oxidation were lower than those required by other known antioxidants. 1,3-diCQA inhibited oxidative damage caused by various factors, including FeSO₄ and AAPH (2,2′-azobis(2-amidinopropane) dehydrochloride). Antioxidant activity can also be detected by the ability of a compound to scavenge reactive oxygen species (ROS). 1,3-diCQA was found to scavenge hydroxyl radical and superoxide radicals, as measured by electron spin resonance (ESR). These data demonstrate that 1,3-diCQA exhibits antioxidant properties, probably through the involvement of a direct scavenging effect on several free radicals.     

食品及临床样本中沙门菌多重耐药相关基因的研究

目的 了解从食品及临床样本中分离的沙门菌整合子以及产超广谱β-内酰胺酶(ESBL)菌分布,以及不同耐药基因与多重耐药之间的关系。方法 利用K-B法进行产ESBL菌表型确证试验;通过聚合酶链式反应方法,对产超广谱β-内酰胺酶沙门菌相关耐药基因(bla_TEM、bla_SHV、bla_CTX)以及可移动元件—整合子基因进行扩增,对整合子可变区扩增产物进行基因测序,分析携带耐药基因盒。结果 共分离309株沙门菌,138株来自食品(禽类96株,生猪肉19株,水产品23株),171株来自临床样本。309株沙门菌耐药率达78.3%,多重耐药率达41.1%,其中禽类耐药率占比最高。共检出56株产ESBL菌,其中35株携带产ESBL菌相关耐药基因(bla _TEM基因型15株,bla_CTX基因型10株,bla _TEM与bla _CTX双基因型10株),未检出bla _SHV基因。检出98株Ⅰ类整合子阳性菌,阳性率为31.7%。其中54株携带...     

Identification and characterization of Dekkera bruxellensis, Candida pararugosa, and Pichia guilliermondii isolated from commercial red wines

Yeast isolates from commercial red wines were characterized with regards to tolerances to molecular SO₂, ethanol, and temperature as well as synthesis of 4-ethyl-phenol/4-ethyl-guaiacol in grape juice or wine. Based on rDNA sequencing, nine of the 11 isolates belonged to Dekkera bruxellensis (B1a, B1b, B2a, E1, F1a, F3, I1a, N2, and P2) while the other two were Candida pararugosa (Q2) and Pichia guilliermondii (Q3). Strains B1b, Q2, and Q3 were much more resistant to molecular SO₂ in comparison to the other strains of Dekkera. These strains were inoculated (10³–10⁴ cfu/ml) along with lower populations of Saccharomyces (<500 cfu/ml) into red grape juice and red wine incubated at two temperatures, 15 °C and 21 °C. Although Saccharomyces quickly dominated fermentations in grape juice, B1b and Q2 grew and eventually reached populations >10⁵ cfu/ml. In wine, Q3 never entered logarithmic growth and quickly died in contrast to Q2 which survived >40 days after inoculation. B1b grew well in wine incubated at 21 °C while slower growth was observed at 15 °C. Neither Q2 nor Q3 produced 4-ethyl-phenol or 4-ethyl-guaiacol, unlike B1b. However, lower concentrations of volatile phenols were present in wine incubated at 15 °C compared to 21 °C.     

Characterization of Listeria monocytogenes strains isolated from Gorgonzola cheese rinds

Listeria monocytogenes is a foodborne pathogen frequently present in ripened soft cheeses. Forty-three strains of L. monocytogenes isolated from the rind of ripened Gorgonzola cheeses produced in 24 different dairy plants were characterized by biotyping, serotyping, and molecular typing. Biotyping was performed by studying two phenotypes closely associated with virulence, such as hemolytic and phospholipase C activities. Traditional typing techniques did not allow a discrimination among the 43 strains studied. All strains showed a good hemolytic activity on blood agar, and only slight differences were observed when titration of hemolytic activity of culture supernatants was performed. Also phospholipase activities were quite similar for all the strains. Concerning serotyping, all strains belonged to serotype 1/2a. The molecular characterization was performed by RAPD-PCR. Combined cluster analysis following PCR amplification experiments allowed to group L. monocytogenes strains into few distinguishable profiles. At a level of similarity of 80%, the 43 strains were grouped into only 5 composite profile groups. Although isolated in 24 different plants, the presence of a few closely related strains demonstrated a possible relationship between these cheese isolates; a special ability of these strains to adapt to Gorgonzola cheese processing environment could be suggested.     

Production of -aminobutyric acid (GABA) by Lactobacillus paracasei isolated from traditional fermented foods

Lactobacillus strains that accumulated γ-aminobutyric acid (GABA) in culture medium were screened to determine strains with high GABA-producing ability. One strain, NFRI 7415, which was isolated from a Japanese traditional fermented fish (funa-sushi), showed the highest GABA-producing ability among the screened strains. Identification tests (i.e., 16S rDNA sequencing and sugar assimilation ability) indicated that NFRI 7415 belongs to Lb. paracasei. The GABA production was further improved by the addition of pyridoxal phosphate to the culture medium and pH regulation of culture medium at pH 5.0. Under optimal cultivation conditions, strain NFRI 7415 produced GABA at a concentration of 302 mm when the glutamate concentration in the culture medium was 500 mm.     

Study of emulsions stabilized with Phaseolus vulgaris or Phaseolus coccineus with the addition of Arabic gum, locust bean gum and xanthan gum

The properties of o/w emulsions stabilized with 1%w/v common bean (Phaseolus vulgaris L.), V or scarlet runner bean (P. coccineus L.), Coc extracted by isoelectric precipitation or ultrafiltration, at pH 7.0 and 5.5, with the addition of Arabic gum, locust bean gum, xanthan gum and a mixture of xanthan gum–locust bean gum (0.1 %w/v and 0.25 %w/v) are studied. The stability of emulsions was evaluated on the basis of oil droplet size, creaming, viscosity and protein adsorption measurements. The addition of Arabic gum, caused an increase in D[4,3] values and a decrease in the amount of protein adsorbed at the interface. The addition of locust bean gum in some emulsions reduced the amount of protein adsorbed. The addition of xanthan and to a less extend of the polysaccharide mixture, promoted a decrease in D[4,3]. So, emulsion stability was affected by the polysaccharide nature. Differences were also observed with respect to the protein nature, the method of its preparation and emulsion's pH. All polysaccharides enhanced the emulsions viscosity with xanthan and xanthan–locust bean gum exhibiting the higher values. V isolates and isoelectricaly precipitated isolates of both V, Coc showed higher viscosity values. The stability was enhanced by the increase of the viscosity of the continuous phase and the creation of a network, which prevents the oil droplets from coalescence.