Chemical structure and antioxidant activity of a new exopolysaccharide produced from Micrococcus luteus

An exopolysaccharide (EPS) reaching a maximum of 13 g/L was isolated from Micrococcus luteus by ethanol precipitation. The crude EPS was purified by chromatography on DEAE-cellulose and Sephacryl S-200, affording a polysaccharide active fraction (AEP) with a molecular weight of ∼137 kDa. AEP was investigated by a combination of chemical and chromatographic methods including FTIR, HPLC, periodate oxidation, methylation and GC–MS. Data obtained indicated that AEP was composed of mannose, arabinose, glucose and glucuronic acid in a molar ratio of 3.6:2.7:2.1:1.0, respectively. The main backbone consists of mannose units linked with (1→6)-glycosidic bonds and arabinose units linked with (1→5)-glycosidic bonds. There is a side chain consisting of mannose units linked with (1→6)-glycosidic bonds at C3, when all glucose and most of glucuronic acid are found in the side chain. The in vitro antioxidant assay showed that AEP possesses DPPH radical-scavenging activity, with an EC₅₀ value of 180 μg/mL.     

Antioxidant property and production of exopolysaccharide from Armillaria mellea in submerged cultures: Effect of culture aeration rate

Effects of culture aeration rate on production and antioxidant property of exopolysaccharide (EPS) by Armillaria mellea were investigated in a 5‐L stirred‐tank bioreactor where an optimal biomass aeration rate of 1.2 vvm with 0.22 g/g cell yield and 0.6 vvm EPS formation rate with 7.66 mg/g product yield were achieved. A two‐stage aeration process to maximize the biomass and EPS productions proceeded with a 1.55‐fold enhancement (from 4.28 to 6.65 g/L) in biomass formation and a 2.68‐fold enhancement (from 86.9 to 233.2 mg/L) in the EPS production, as compared with those from the aeration rate of 0.3 vvm. The molecular weights of EPS in cultures of different aeration rates are closely correlated with their protein/polysaccharide ratios (R²=0.830) and EC₅₀ (EC₅₀, the effective concentration where the antioxidant property is 50%) values in antioxidant activity (R²=0.960), reducing power (R²=0.894) and chelating ability (R²=0.954). EPS from the two‐stage aeration rate culture shows a strong antioxidant property by the conjugated diene method, reducing power and chelating ability on ions. Therefore, we present results to regulate and to optimize A. mellea cultures to efficiently produce biomass and EPS. The fermented EPS has the potential to be used as for antioxidant‐related functional foods and pharmaceutical industries.     

Enhanced exopolysaccharide production and biological activity of Lactobacillus rhamnosus ZY with calcium and hydrogen peroxide

Exopolysaccharides (EPS) are important food and drug additives with beneficial antioxidant, anticancer, and immune-related effects on human health. However, the EPS is limited by low yields and the need for complex culture conditions in fermentation. Here, we report that hydrogen peroxide and calcium stimulated probiotic activity and production of crude exopolysaccharide (c-EPS) by Lactobacillus rhamnosus ZY. Accordingly, supplementation with 3 mM H₂O₂ allowed c-EPS biosynthesis to reach 567 mg/L after 24 h. Addition of both CaCl₂ and H₂O₂ resulted in a c-EPS yield of 2498 mg/L after 12 h, over 9-fold higher than that of an anaerobic culture. We observed that exposure to calcium and hydrogen peroxide made the cells more hydrophobic and led to the over-expression of GroEL, NADH peroxidase, and glyceraldehyde 3-phosphate dehydrogenase, thus increasing energy storage and EPS production. Chromatographic analysis revealed c-EPS was composed mainly of mannose (5.1%), galactose (15.3%), glucose (20–30%), and rhamnose (50–60%). Preliminary in vitro tests revealed that H₂O₂ and CaCl₂ enhanced the 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radical scavenging capacities, resulting in a notable protective effect against oxidative damage in NIH/3T3 cells. Our study provides a simple and cost-effective approach for achieving high yields of good quality EPS using Lactobacillus rhamnosus.     

Production and purification of a novel exopolysaccharide from lactic acid bacterium Streptococcus phocae PI80 and its functional characteristics activity in vitro

Optimum culture conditions which ease the synthesis of a novel exopolysaccharide (EPS) from a potent marine strain Streptococcus phocae was proposed in this study. The strain grows well at 35 °C, pH 7.0 and NaCl (2%) with lactose and yeast extract as best carbon and nitrogen sources. The maximum yield of EPS (11.75 and 12.14 g/L) was obtained in the presence of lactose and yeast extract at a concentration of 20 g/L respectively. EPS was refined by gel filtration chromatography using phenyl Sepharose column which revealed the presence of arabinose, fructose and galactose sugar units with molecular mass about 2.8 × 10⁵ Da. Emulsifying and flocculating stability of EPS compared with three commercial hydrocolloids. EPS exhibited better activities which are similar to that of commercial hydrocolloids. Both crude and purified EPS exhibited strong antioxidant potential by quenching hydroxyl and superoxide anion radicals. Antibiofilm activity by inhibition of Gram positive and Gram negative biofilm forming bacteria was evident in our studies. Potential antioxidant activity and biofilm inhibiting property of EPS may lead to the development of novel food grade adjuncts.     

小分子Rhizobium sp. N613胞外多糖的制备及其抗肿瘤活性

采用微波辐照氧化技术,降解大分子Rhizobium sp.N613胞外多糖(REPS)为小分子多糖(LREPS),以改善其理化及抗肿瘤活性,提高应用价值和拓展应用范围。通过正交试验考察了底物浓度、H2O2浓度、微波辐照强度和辐照时间对降解产物分子量的影响并获得一系列LREPS产物。选取4组分子量段(10以下、10、20和30 kD左右)的LREPS代表性样品进行小鼠体内S180抑瘤效果检测,其中分子量段为10.352 kD的LREPS效果最佳,抑瘤率高达52.8%,确定为LREPS的最适分子量段。其制备工艺条件为:REPS浓度为2 g/L、H2O2浓度为6%、微波辐照强度为375 W、微波辐照时间为2 min;理化分析结果表明,LREPS的红外图谱与REPS相似,仍为β-D-吡喃葡聚糖。其溶解度由原多糖的8.00 g/L增至15.73 g/L,特性粘数由原多糖的527.64 mL/g降至351.67 mL/g。建立了LREPS制备工艺并获取了相关理化及抗肿瘤技术参数,为该多糖制剂的生产应用奠定一定基础。     

Optimisation of exopolysaccharide production by Gomphidius rutilus and its antioxidant activities in vitro

The production conditions of the Gomphidius rutilus exopolysaccharides (GREP) in submerged culture were optimised, and the antioxidant activities of GREP in vitro were evaluated. The optimal culture medium constituents were determined as follows: 30 g/L sucrose, 3.0 g/L soybean meal, 0.25 g/L MgSO₄, 1.5 g/L K₂HPO₄, 0.5 g/L KH₂PO₄, 0.03 g/L ZnSO₄, and 0.01 g/L FeSO₄. The optimum parameters for the liquid fermentation were as follows: temperature, 25 °C; cultivation time, 6 d; initial pH, 8.0; volume of medium, 150 mL; and rotary speed, 180 rpm. GREP content and dry cell weight in optimised conditions were 540.1 ± 15.9 mg/L and 8.2 ± 0.3 g/L, respectively. GREP content under the optimised conditions was 2.5 times than that under the basic culture medium and initial conditions. GREP demonstrated positive antioxidant potential on superoxide anion radical, 1,1-diphenyl-2-picrylhydrazyl, and hydroxyl radical scavenging, and reducing power.     

Antioxidant and free radical scavenging activities of an exopolysaccharide from a probiotic bacterium

Probiotic bacteria synthesize extracellular polysaccharides (EPSs) with commercially significant physiological and therapeutic activities. This important class of biomolecules is also characterized by their ability to remove reactive oxygen species (ROS) that are formed in the intestine by various metabolic reactions; hence, they exhibit antioxidant activities. Our probiotic bacterium, Bacillus coagulans RK-02, produces an EPS during the exponential and stationary growth phases when grown in a glucose mineral salts medium. The time course of EPS synthesis was studied with respect to biomass growth. The antioxidant and free radical scavenging potential of isolated EPS were studied by various methods, including the beta-carotene-linoleic acid model system, a superoxide radical scavenging assay using the PMS-NADH-nitroblue tetrazolium system, the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, a hydroxyl radical scavenging assay using the ascorbic acid-Cu(2+)-cytochrome c system and an in vitro microsome peroxidation inhibition study using a thiobarbituric acid assay. The antioxidant activities were compared to known antioxidants vitamin C and E, which were used as reference standards. The results showed that the EPS, which is a heteropolymer composed of four monosaccharides, produced by B. coagulans RK-02 had significant antioxidant and free radical scavenging activities.     

Chemical constituents from Tribulus terrestris and screening of their antioxidant activity

Two oligosaccharides (1, 2) and a stereoisomer of di-p-coumaroylquinic acid (3) were isolated from the aerial parts of Tribulus terrestris along with five known compounds (4–8). The structures of the compounds were established as O-β-d-fructofuranosyl-(2 → 6)-α-d-glucopyranosyl-(1 → 6)-β-d-fructofuranosyl-(2 → 6)-β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranosyl-(6 → 2)-β-d-fructofuranoside (1), O-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 2)-β-d-fructofuranoside (2), 4,5-di-p-cis-coumaroylquinic acid (3) by different spectroscopic methods including 1D NMR (¹H, ¹³C and DEPT) and 2D NMR (COSY, TOCSY, HMQC and HMBC) experiments as well as ESI-MS analysis. This is the first report for the complete NMR spectral data of the known 4,5-di-p-trans-coumaroylquinic acid (4).The antioxidant activity represented as DPPH free radical scavenging activity was investigated revealing that the di-p-coumaroylquinic acid derivatives possess potent antioxidant activity so considered the major constituents contributing to the antioxidant effect of the plant.     

Synthesis and structural characterization of silver nanoparticles using bacterial exopolysaccharide and its antimicrobial activity against food and multidrug resistant pathogens

A green, simple, and effective approach was performed to synthesize potent silver nanoparticles (SNPs) using bacterial exopolysaccharide as both a reducing and stabilizing agent. The synthesized SNPs were characterized using UV-vis spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and Fourier-transform-infrared spectra analyses. The SNPs varied in shape and were multidispersed with a mean diameter of 10 nm ranging from 2 to 15 nm and were stable up to 2 months at room temperature. The antimicrobial activity of the SNPs was analyzed against bacterial and fungal pathogens using the agar well diffusion method. Dose dependent inhibition was observed for all bacterial pathogens. The multidrug resistant pathogens P. aeruginosa and K. pneumonia were found to be more susceptible to the SNPs than the food borne pathogen L. monocytogenes. The fungi Aspergillus spp. exhibited a maximum zone of inhibition compared to that of Penicillum spp. These results suggest that exopolysaccharide-stabilized SNPs can be used as an antimicrobial agent for various biomedical applications.     

Characterization and antioxidant activity of Ginkgo biloba exocarp polysaccharides

Ginkgo biloba exocarp polysaccharide (GBEP) was obtained by hot water extraction, the crude polysaccharide was deproteinized by Sevag method and fractionized by a DEAE Sepharose fast flow anion-exchange column. Five fragments were obtained, including neutral polysaccharide (GBEP-N) and four acidic polysaccharides (GBEP-A1, GBEP-A2, GBEP-A3 and GBEP-A4). GBEP-N and GBEP-A3 were further purified by Superdex 200 gel column chromatography. The resulted two fractions GBEP-NN, and GBEP-AA were characterized by FT-IR, and HPGFC (high pressure gel filtration chromatography). Monosaccharide composition was determined by RP-HPLC method of precolumn derivatization with 1-phenyl-3-5-pyrazolone. GBEP-NN was mainly composed of rhamnose, arabinose, mannose, glucose and galactose, while GBEP-AA was mainly made up of mannose, rhamnose, glucuronic acid, galacturonic acid, galactosamine, glucose, galactose, xylose, arabinose, and fucose. The crude GBEP exhibited certain antioxidant activity. At the concentration of 5 mg/mL, the hydroxyl radical scavenging effect of GBEP was 90.52%, greater than 77.37% for the positive control ascorbic acid.     

Production and characterisation of exopolysaccharide from Streptomyces carpaticus isolated from marine sediments in Egypt and its effect on breast and colon cell lines

Twenty streptomycete strains were isolated from marine sediment samples collected from Nabq area, Sharm El-Sheikh, Red Sea Coast, Egypt. Four of them produce exopolysaccharides (EPS) showing marked in vitro antitumor activities. Morphological and cultural characteristics of the most significant strain (No. 3) were shown. Moreover, the sequence of this strain showed similarity with Streptomyces carpaticus. The results reveal that EPS produced by Streptomyces carpaticus No. 3 had high cytotoxicity reaching 51.7% and 59.1% against human tumor cells of breast and colon lines respectively. A chemical analysis of EPS indicated that the composing monosaccharides were galactouronic acid, glucose, xylose, galactose, mannose, and fructose with relative ratio of 3:1:1:2:2:1 respectively, with an average molecular weight (Mw) 1.180 × 10⁵?g/mol and of a number average molecular weight (Mn) 1.052 × 10⁵?g/mol. Also the EPS contained uronic acid (0.5072%) and monosaccharide sulphates (21.753%).     

金花菌黄色素的稳定性及其抗氧化活性研究

【目的】评价茯砖茶金花菌黄色素的稳定性和抗氧化性能。【方法】以色素保存率为指标, 研究温度、光照和pH对黄色素稳定性的影响。并对还原能力、DPPH·清除能力和H2O2诱导的红细胞溶血抑制能力进行测定, 考察黄色素的抗氧化性能。【结果】该色素在低温下保存7 d保存率高于98.88%, 温度升高, 保存率降低; 光照尤其是太阳光对其稳定性影响较大; 黄色素在pH 2?10较稳定, pH 12时色素保存率仅为46.22%。低浓度黄色素具有明显高于维生素E (VE)的还原能力、DPPH·清除率和溶血抑制率, 其中DPPH·的EC50低于50 mg/L。【结论】金花菌黄色素对热、酸和弱碱较稳定, 对强碱和太阳光极不稳定, 并有优良的抗氧化能力, 研究和开发前景良好。     

Production, characterization and antioxidant activity of exopolysaccharides from submerged culture of Morchella crassipes

The aim of this work was to investigate the fermentation optimization, molecular characterization, and antioxidant activity in vitro of exopolysaccharides (EPS) from Morchella crassipes in submerged culture. Firstly, an optimal medium for EPS production was obtained by single-factor experiment and central composite design as follows: maltose 44.79?g/L and tryptone 4.21?g/L. Then, one fraction of EPS was obtained from the culture filtrates by size exclusion chromatography and the molecular characteristics were examined by a multi-angle laser light scattering and refractive index detector system. The weight-average molar mass and the polydispersity ratio of the EPS fraction were revealed to be 1.961?×?10(4)?g/mol and 1.838, respectively. FT-IR spectroscopy was used for obtaining vibrational spectra of the purified EPS fraction. Finally, the antioxidant activity of EPS was investigated and the relationship with molecular properties was discussed as well.     

Structural characterization and antioxidant properties of an exopolysaccharide produced by the mangrove endophytic fungus Aspergillus sp. Y16

A homogeneous exopolysaccharide, designated As1-1, was obtained from the culture medium of the mangrove endophytic fungus Aspergillus sp. Y16 and purified by anion-exchange and gel-permeation chromatography. Results of chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopy showed that As1-1 was mainly composed of mannose with small amounts of galactose, and that its molecular weight was about 15 kDa. The backbone of As1-1 mainly consists of (1 → 2)-linked α-d-mannopyranose units, substituted at C-6 by the (1 → 6)-linked α-d-mannopyranose, (1→)-linked β-d-galactofuranose and (1→)-linked β-d-mannopyranose units. As1-1 possessed good in vitro antioxidant activity as evaluated by scavenging assays involving 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radicals. The investigation demonstrated that As1-1 is an exopolysaccharide different from those of other marine microorganisms, and could be a potential antioxidant and food supplement.     

Evaluation of lactic acid bacterial strains of boza for their exopolysaccharide and enzyme production as a potential adjunct culture

Boza is a non-alcoholic beverage obtained from fermented cereals. Thirteen lactic acid bacteria (LAB), previously isolated from boza were identified and evaluated to determine the various technological properties for selecting appropriate strains as adjunct culture in boza. Each isolate was checked for purity, Gram-stained and tested for the catalase and oxidase activity and then subjected to identification by polymerase chain reaction (PCR) with partial 16S rRNA gene sequencing. The tests for carbohydrate fermentation and enzyme profiles were carried out with the API 50 CHL and API ZYM galleries, respectively. Exopolysaccharide (EPS) production of strains was determined by Fourier transform infrared spectroscopy (FT-IR) and quantified by the phenol sulphuric acid method. To our best knowledge, this is the first study reporting on Lactococcus garvieae (E32), Pediococcus parvulus (E42) and Streptococcus macedonicus (A15) in boza. All strains, except S. macedonicus (A15) produced EPS. Leuconostoc citreum (E55) and Lactococcus lactis (A47) were the highest EPS producing strains, yielding 2.39 ± 0.49 and 1.98 ± 0.23 g/L of EPS, respectively. Lactobacillus paracasei (D41), Lactobacillus plantarum (B2), Lactococcus lactis (F39) and among low-EPS producing strains Lactobacillus coryniformis (C55), L. paracasei (E8), and P. parvulus (E42) were evaluated to be promising candidates as potential adjunct culture in boza. The variety of enzyme production was also concern. Lc. garvieae (E32) was found to produce the largest variety of enzymes among the strains. FT-IR spectroscopy can be used for the assessment of EPS production by microorganisms reliably and accurately.     

Optimization of medium composition for the production of exopolysaccharides from Phellinus baumii Pilát in submerged culture and the immuno-stimulating activity of exopolysaccharides

Optimization of medium composition for the production of exopolysaccharides (EPS) from Phellinus baumii Pilát in submerged culture and the immuno-stimulating activity of EPS were carried out. Firstly, the medium components having significant effect on EPS production were screened out to be glucose, yeast extract and diammonium oxalate monohydrate by using a 2⁽⁷⁻³⁾ fractional factorial design. Secondly, the concentrations of the three factors were optimized using central composite design in response surface methodology. As results, a quadratic model was found to fit for EPS production, and the optimal medium composition was determined as following (g/l): 34.12 glucose, 4 peptone, 5.01 yeast extract, 0.88 diammonium oxalate monohydrate, 0.75 MgSO₄ and 1 KH₂PO₄ and 0.0075 thiamine (VB₁). A yield of 2.363 ± 0.04 g/l for EPS was observed in verification experiment. Finally, EPS from P. baumii Pilát was found to have direct immuno-stimulating activity in vitro on splenocyte proliferative response and acid phosphatase activity in peritoneal macrophages in a dose-dependent manner.     

大型真菌抗氧化活性小分子次生代谢产物的研究进展

大型真菌是菌物中形成大型子实体的一类真菌,该类群中食药用资源极为丰富,许多种类具有显著的抗氧化活性。本文综述了国内外有关大型真菌具抗氧化活性的小分子次生代谢产物的化学结构及其活性的研究概况,以期对大型真菌的活性筛选、化学分析和开发利用提供借鉴。     

Norditerpene alkaloids from Delphinium linearilobum and antioxidant activity

From the roots of Delphinium linearilobum (Trautv.) N. Busch two new norditerpene alkaloids linearilobin and linearilin, and the known alkaloids lycoctonine, 14-acetyltalatizamine, browniine, cammaconine, talatizamine, and cochlearenine were isolated. Spectroscopic techniques were used for structure determination. Antioxidant activity was performed by DPPH and metal chelating activity assays.     

The use of classification methods for modeling the antioxidant activity of flavonoid compounds

A study using two classification methods (SDA and SIMCA) was carried out in this work with the aim of investigating the relationship between the structure of flavonoid compounds and their free-radical-scavenging ability. In this work, we report the use of chemometric methods (SDA and SIMCA) able to select the most relevant variables (steric, electronic, and topological) responsible for this ability. The results obtained with the SDA and SIMCA methods agree perfectly with our previous model, in which we used other chemometric methods (PCA, HCA and KNN) and are also corroborated with experimental results from the literature. This is a strong indication of how reliable the selection of variables is. Three-dimensional projection of the hyperboxes for Classes 1 (right) and 2 (left)     

Encapsulation and release of a bacterial carotenoid from hydrogel matrix: Characterization,kinetics and antioxidant study

Various natural polymers with hydrophilic properties have been used to form hydrogels for the encapsulation and delivery of nutrients and drugs in food and pharmaceutical industries. Among them, chitosan (ChiHG)‐ and alginate (AlgHG)‐ based hydrogels have been extensively explored for delivery of several nutraceuticals in recent years. Release of natural canthaxanthin (CX) obtained from Dietzia maris NITD (accession number: HM151403) has been investigated with emphasis on biomedical applications. Significant changes (P < 0.05) in degree of swelling and moisture content (% dry basis) were found after encapsulation of bacterial canthaxanthin (BCX), but the gel content remained unchanged. BCX encapsulation efficiency was calculated to be 55.92% and 60.45% in ChiHG and AlgHG, respectively. A noticeable change in heat of fusion d melting point was recorded in ChiHG and AlgHG after BCX encapsulation. Swelling and BCX release from gel matrix was performed under two different pH (1.2 and 7.4). The results showed that swelling of hydrogel and BCX release was facilitated at higher pH (7.4) than acidic pH (1.2). With regard to the release kinetics data, it was found that BCX is released from bothand AlgHG in a diffusion transport method. In addition, antioxidant activity of BCX encapsulated hydrogels was found significantly higher (P < 0.001) in terms of DPPH, ABTS, nitrite, hydroxyl radical scavenging and reducing power assay. These results indicated that BCX can be successfully encapsulated into a polymeric hydrogel to obtain a dynamic biomaterial that may be used in drug delivery applications in future.