The fucoidans from brown algae of Far-Eastern seas: Anti-tumor activity and structure–function relationship

The sulfated polysaccharides from brown algae – the fucoidans – are known to be a topic of numerous studies, due to their beneficial biological activities including anti-tumour activity. In this study the effect of fucoidans isolated from brown algae Saccharina cichorioides, Fucus evanescens, and Undaria pinnatifida on the proliferation, neoplastic transformation, and colony formation of mouse epidermal cells JB6 Cl41, human colon cancer DLD-1, breast cancer T-47D, and melanoma RPMI-7951 cell lines was investigated. The algal fucoidans specifically and markedly suppressed the proliferation of human cancer cells with less cytotoxic effects against normal mouse epidermal cells. The highly sulfated (1 → 3)-α-l-fucan from S. cichorioides was found to be vitally important in the inhibition of EGF-induced neoplastic transformation of JB6 Cl41 cells. In colony formation assay the fucoidans from different species of brown algae showed selective anti-tumour activity against different types of cancer, which depended on unique structures of the investigated polysaccharides. These results provide evidence for further exploring the use of the fucoidans from S. cichorioides, F. evanescens, and U. pinnatifida as novel chemotherapeutics against different types of cancer.     

Sulfated modification of polysaccharides: Synthesis,characterization and bioactivities

BackgroundPolysaccharides are a kind of biological macromolecular substance with multiple biological effects. Natural polysaccharides derived from plants and fungi are known as ideal raw food supplements for health food and pharmaceuticals due to their few side effects. Sulfated modification could significantly improve structure characteristics, promote bioactivities, and even add new bioactivities to polysaccharides. Thus, sulfated polysaccharides are increasingly causing more attention, as they have been proved to possess a variety of biological activities, including antioxidant, anticancer, and immunoregulatory, and anticoagulant activities. Furthermore, recent advances in synthesis, characterization and bioactivities of sulfated polysaccharides can promote its application in the food industry or pharmaceutics.Scope and approachThis paper reviewed the main methods of sulfated modification, structural changes and the bioactivities of sulfated polysaccharide derivatives. We have comprehensively discussed biological activities of sulfated polysaccharides, emphatically the effects of sulfated group, composition, functional groups, as well as their replaced position on the bioactivities of sulfated polysaccharides, in order to reveal the potential mechanism of sulfation on bioactivities of polysaccharides.Key findings and conclusionsThis paper reviewed the recent research in the sulfated modification of polysaccharides and provided future directions for research in this area. There are many methods for sulfated modification, such as chlorosulfonic acid-pyridine method, concentrated sulfuric acid method, and sulfur trioxide-pyridine method, which could improve anti-coagulant, anti-oxidative, immunoregulation, anti-tumor, and anti-virus activities of polysaccharides. Sulfated modification could change bioactivities of polysaccharides due to their effects on structure characteristics. DS, monosaccharide compositions, replaced position of sulfated groups were considered to contribute to their bioactivities promotion. Further studies are required to explore the application of sulfated polysaccharides in pharmaceutical and food industries.     

Effect of sulfation on the physicochemical and biological properties of citrus pectins

Citrus pectins were subjected to chemical modification, specifically sulfation, and the antimicrobial and anticoagulant activities of the derivative were investigated. Compared to native pectin, the FT-IR spectra of the derivative showed two new absorption bands at 1250 cm⁻¹ (SO) and 810 cm⁻¹ (C–O–S), implying that the pectin was successfully sulfated. The degree of substitution was also determined to be 0.15 by elemental analysis. In rheological measurements, sulfation gave rise to significant reduction of viscosity of pectin. Moreover, the pectin derivative exhibited improved antimicrobial effects against Bacillus cereus and Vibrio fischeri and the anticoagulant activity, which increased in a concentration-dependent manner. These results demonstrated that the incorporation of sulfate groups into the pectin structure appeared to play an important role in improving its biological activities.     

Three sulphated polysaccharides isolated from the mucilage of mud snail, Bullacta exarata philippi: Characterization and antitumour activity

Three sulphated polysaccharides, coded as BEMPA, BEMPB₁, BEMPB₂, were extracted from the mucilage of mud snail of Bullacta exarata and purified by DEAE-cellulose ion-exchange and size-exclusion chromatography. Structural analysis of purified polysaccharides by chemical and biochemical methods revealed BEMPA was a high (1→3,4)-linked mannose-containing polysaccharide with molecular weight of 22,977 Da. BEMPB₁, with molecular weight of 64,117 Da, was a high (1→3)-linked arabinose-containing polysaccharide. BEMPB₂ was mainly composed of (1→3,4)-linked mannose with molecular weight of 47,507 Da. The comparison between sulphated polysaccharides and their desulphated products showed that sulphate substitutions of BEMPB₁ were deduced to be at the C-3 of (1→4)-linked mannose, while sulphate substitutions of BEMPA and BEMPB₂ were at C-4 of (1→3)-linked mannose. Furthermore, BEMPA exhibited highest inhibitory effects on growth of B-16 melanoma cells, and IC₅₀ were 31.1 μg/mL.     

Chemical composition,antioxidant and anti-inflammatory properties for ethanolic extracts from Pleurotus eryngii fruiting bodies harvested at different time

Pleurotus eryngii, a popular edible mushroom in Taiwan, is usually cultivated using sawdust medium packing bags through several procedures including culture medium confection, bagging and sterilization, spawn inoculation, fostering mycelia, full growth of mycelia, and inducing fruiting body formation. In this study, P. eryngii commercial products harvested at the 10th, 12th and 15th days after inducing the fruiting body formation were extracted with ethanol, individually. Through determination of chemical composition, antioxidant and anti-inflammatory properties of these extracts, the optimal harvest time of P. eryngii fruiting bodies with higher functional attributes was revealed. The earlier harvested sample extracts had higher effects for scavenging 2,2-diphenyl-1-picrylhydrazyl radicals, reducing power, chelating power, and β-carotene bleaching inhibition, as well as down-regulating lipopolysaccharide-stimulated nitric oxide, prostaglandin E₂, inducible nitric oxide synthase, and cyclooxygenase-2 expression in RAW264.7 macrophages. These functional responses were closely related to levels of phytochemical components including phenolic acids, flavonoids, tocopherols and carotenoids.     

Structure of a galactoarabinoglucuronoxylan from tamarillo (Solanum betaceum), a tropical exotic fruit,and its biological activity

Tamarillo (Solanum betaceum) is a tropical exotic fruit whose polysaccharides were extracted from the ripe pulp. After various purification steps, homogeneous fractions (designated PTW, STK-1000R and PF) were analyzed by sugar composition, HPSEC, methylation and NMR spectroscopy analysis. The results showed that the fraction PTW consisted of a linear arabinan with (1 → 5)-linked α-l-arabinofuranosyl units. Fractions designated as STK-1000R and PF contained galactoarabinoglucuronoxylans, with (1 → 4)-linked β-d-Xylp residues in the backbone, carrying branches exclusively at O-2. The polysaccharide in STK-1000R is less branched than that in the PF fraction (∼20.0% and 36.5%, respectively), with side-chains formed by (1 → 5)-linked α-l-Araf residues and (1 → 4)-linked α-d-GlcpA residues and with non-reducing end units formed by α-l-Araf, β-Arap, β-d-Galp, α-d-GlcpA and 4-O-Me-α-d-GlcpA. Intraperitoneal administration of the STK-1000R fraction in mice significantly reduced the number of abdominal constrictions induced by 0.6% acetic acid and the inflammatory phase of nociception induced by 2.5% formalin, indicating that that fraction has an antinociceptive effect on inflammatory pain models.     

A comparative study of tocopherols composition and antioxidant properties of in vivo and in vitro ectomycorrhizal fungi

In aerobic organisms, the free radicals are constantly being produced during the normal cellular metabolism. The antioxidant properties of many organisms and particularly of wild mushrooms with their content in antioxidant compounds such as tocopherols, can detoxify potentially damaging forms of activated oxygen. Herein, a comparative study of tocopherols composition and antioxidant properties of in vivo (fruiting bodies) and in vitro (mycelia) ectomycorrhizal fungi: Paxillus involutus and Pisolithus arhizus. Tocopherols were determined by high performance liquid chromatography (HPLC) coupled to a fluorescence detector. The antioxidant properties were studied in terms of DPPH radical-scavenging activity, reducing power and inhibition of β-carotene bleaching. Fruiting bodies revealed the highest antioxidant properties, including scavenging effects on free radicals (EC₅₀ = 0.61 and 0.56 mg/ml) and inhibition of lipid peroxidation capacity (EC₅₀ = 0.40 and 0.24 mg/ml for P. involutus and P. arhizus, respectively), than mycelia produced in vitro cultures. Nevertheless, mycelia revealed higher levels of total tocopherols than fruiting bodies, and particularly P. arhizus mycelium proved to be a powerful source of γ-tocopherol (154.39 μg/g dry weight).     

Microbiological,chemical and sensory aspects of bread supplemented with different percentages of the culinary mushroom Pleurotus eryngii in powder form

Pleurotus eryngii (DC.) Quél. powder was used in bread production. Three dough trials (0, 5 and 10% of mushroom) were obtained with commercial baker's yeast. P. eryngii powder was first tested against several yeast species; 10% P. eryngii trial was characterised by the highest pH and total titratable acidity. P. eryngii did not influence negatively the fermentation process, since all trials reached yeast levels of 10⁸ CFU g⁻¹. Mushroom powder decreased bread height and softness, increased crust redness and crumb void fraction and cell density and, although the breads were scored diverse, the overall assessment was comparable. The final breads provided higher concentrations of thiamin, riboflavin and pantothenic acid than control breads and, mostly importantly, supplied biotin, cobalamin and cholecalciferol generally absent in wheat bread. P. eryngii can be cultivated on food residues. Thus, its inclusion in functional bread production represents an optimal strategy for the valorisation of food processing by-products.     

Arabinan and arabinan-rich pectic polysaccharides from quinoa (Chenopodium quinoa) seeds: Structure and gastroprotective activity

After removal of starch, cell wall polysaccharides of seeds of quinoa were studied. They were extracted successively with water and with aq. 10% KOH. The extracted polysaccharides were fractionated and purified by freeze–thaw treatment and by sequential ultrafiltration through membranes. The purified fractions (PQW, K2-30EM, K1-10RM and K1-30RM) were analyzed by sugar composition, HPSEC, methylation and ¹³C NMR spectroscopy analysis. The results showed that PQW consisted of a linear arabinan with (1 → 5)-linked α-l-arabinofuranosyl units. Fractions K2-30EM, K1-10RM and K1-30RM were related to rhamnogalacturonan type I with a branched arabinan and galactan side-chains. This arabinan has (1 → 5)-linked α-l-arabinofuranosyl units substituted exclusively in O-3. The main differences between these fractions were their molecular mass and content of Rha and GalA, which probably arise from an increase in their rhamnogalacturonan backbone. A pool of these polysaccharides (arabinan and arabinan-rich pectic polysaccharides) showed gastroprotective activity on ethanol-induced acute gastric lesions in rats.     

烤烟多糖的硫酸化修饰及抗氧化活性

为了优选烤烟多糖硫酸化修饰的最佳条件,提高烤烟多糖抗氧化活性,采用超声辅助法提取烟叶多糖,并通过氯磺酸-吡啶法对其进行了硫酸化修饰;通过单因素实验和正交实验,确定了硫酸化反应的最佳工艺条件。采用DPPH(1,1-二苯基-2-三硝基苯肼)法和邻二氮菲法进行了抗氧化活性研究。结果表明:①硫酸化反应的最佳工艺条件为氯磺酸与吡啶的体积比l:6,反应时间3 h,反应温度80℃。在此条件下多糖硫酸酯的硫酸基质量分数为20.03%,取代度为2.587。②烤烟多糖经硫酸化修饰后,其抗氧化活性显著提高。      

Galactooligosaccharides derived from lactose and lactulose: influence of structure on Lactobacillus, Streptococcus and Bifidobacterium growth

The effect of structure on the fermentative properties of potential prebiotic trisaccharides derived from lactulose like 6′-galactosyl-lactulose (β-d-galactopyranosyl-(1 → 6)-β-d-galactopyranosyl-(1 → 4)-β-d-fructopyranose), 4′-galactosyl-lactulose (β-d-galactopyranosyl-(1 → 4)-β-d-galactopyranosyl-(1 → 4)-β-d-fructopyranose), and 1-galactosyl-lactulose (β-d-galactopyranosyl-(1 → 4)-β-d-fructopyranosyl-(1 → 1)-β-d-galactopyranose); and from lactose like 4′-galactosyl-lactose (β-d-galactopyranosyl-(1 → 4)-β-d-galactopyranosyl-(1 → 4)-β-d-glucopyranose) and 6′-galactosyl-lactose (β-d-galactopyranosyl-(1 → 6)-β-d-galactopyranosyl-(1 → 4)-β-d-glucopyranose), has been assessed in vitro. Fermentations with twelve pure strains of Lactobacillus, Streptococcus and Bifidobacterium were carried out using the purified trisaccharides as the sole carbon source, and bacteria growth was evaluated at 600 nm by means of a microplate reader during 48 h. Maximum growth rates (μ_max) and lag phase were calculated. In general, all the strains tested were able to utilize lactulose and pure trisaccharides derived from lactulose and lactose when they were used as sole carbon source. Nonetheless, glycosidic linkage and/or the monosaccharide composition of the trisaccharides affected the individual strains lag phase, cell densities and growth rates. A general preference towards β-galactosyl residues β(1-6) and β(1-1) linked over those β(1-4) linked was observed, and some strains showed higher cell densities and speed of growth on 6′-galactosyl-lactulose than on 6′-galactosyl-lactose. This is the first study of the effect of lactulose-derived oligosaccharides on pure culture growth which shows that transglycosylation of lactulose allows for obtaining galactooligosaccharides with new glycosidic structures and would open new routes to the synthesis of compounds with potential prebiotic effects.     

A further amendment to the classical core structure of gum arabic (Acacia senegal)

Using the more recently available techniques such as methylation–GC–MS, 1D (¹H, ¹³C) and 2D (COSY, TOCSY, HMQC and HMBC) NMR spectral analysis, we have revisited the classical structure of gum arabic (Acacia senegal). Methylation and GC–MS analysis confirmed that gum arabic (A. senegal) is a highly branched polysaccharide with the backbone composed of 1,3-linked galactopyransyl (Galp) residues substituted at O-2, O-6 or O-4 positions. The terminal sugar residues are 59.5% of the total sugars. The residues of →2,3,6-β-d-Galp1→, →3,4-Galp1→, →3,4,6-Galp1→ and substitutions at O-2 and O-4 position were not identified in previous studies.     

Dietary polysaccharide extracts of Agaricus brasiliensis fruiting bodies: chemical characterization and bioactivities at different levels of purification

Polysaccharides of the European strain of A. brasiliensis were obtained by hot water extraction and ethanol precipitation (HWPE I) of fruiting bodies, and further purified by dialysis (HWPE II) and pronase incubation (PPE). These polysaccharides consisted mainly of (1 → 6)-β-d-glucans. PPE was free of proteins and polyphenols as demonstrated by quantitative assays and NMR profiling. They showed a clear IFN-γ inducing activity in human PBMCs, which suggests these polysaccharides to have proinflammatory effects. Treatment by β-glucosidase caused the polysaccharides to be degraded into smaller fragments and at the same time increased their IFN-γ inducing activity in PBMCs fourfold.In vitro, PPE showed a dose-dependent inhibition of the proliferation of the human leukemia Jurkat cell. At 100 μg/mL the cells’ viability was decreased by appr. 51% compared to the control. EPR spin trapping demonstrated a high antioxidative activity against ^•OH and ^•O2⁻ radicals of HWPE I and PPE. Further, the results of the antioxidant assays indicated that antioxidant activity against ^•OH radicals in the Fenton system was achieved through scavenging or through chelating iron mechanisms.The good immunomodulating and antioxidative properties of A. brasiliensis polysaccharide extract obtained by hot water extraction and ethanol precipitation make it suitable for everyday use as an inexpensive dietary supplement.     

Chemical characterisation and hypolipidaemic effects of two purified Pleurotus eryngii polysaccharides

This study is focused on the isolation and characterisation of two purified polysaccharide fractions (namely PPEP‐1 and PPEP‐2) from Pleurotus eryngii (P. eryngii) and evaluation of their hypolipidaemic effects. The Congo red analysis indicated that PPEP‐2 but not PPEP‐1 possessed a triple‐helix conformation. The atomic force microscope analysis revealed that PPEP‐1 and PPEP‐2 showed different polysaccharide chain conformations. Importantly, the mice treated with PPEP‐1 showed significantly lowered serum levels of total cholesterol (TC), triglyceride (TG) and low‐density lipoprotein cholesterol (LDL‐c) and increased high‐density lipoprotein cholesterol when compared with the hyperlipidaemia mice induced by the high‐fat diet. However, PPEP‐2 revealed less hypolipidaemic effect than PPEP‐1. Additionally, both PPEP‐1 and PPEP‐2 demonstrated remarkable hypolipidaemic effects by decreasing levels of serum TC, TG and LDL‐c in the hyperlipidaemic model induced by P‐407. Taken together, our findings suggest that the P. eryngii polysaccharides, especially PPEP‐1, could be developed as a natural functional food supplement for preventing hyperlipidaemia.     

Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii

Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels.     

Isolation and structural characterisation of pectin from endocarp of Citrus depressa

A polysaccharide was extracted with hot HCl from the endocarp of Citrus depressa grown in Okinawa, Japan. The yield was 4.1% on a fresh weight basis. Composition of the polysaccharide was 89.3% total carbohydrate, 79.2% uronic acid, 4.1% ash and 8.8% moisture. The degree of methoxylation was estimated to be 66.2%. The polysaccharide was composed of d-GalA, d-Gal, l-Ara and l-Rha in the ratio of 100:10.3:1.53:0.94, respectively. The molecular mass was estimated to be approximately 4.1 × 10⁴. NMR spectra indicated that the polysaccharide was mainly composed of (1→4)-linked α-d-GalA and (1→4)-linked β-d-Gal. Methylation analysis results identified 1→2 and 1→2,4 linked Rha, 1→4, 1→3, 1→6 and 1→3,6 linked Gal. The results indicated that the polysaccharide was a pectin, which was relatively simpler than other pectins. The polysaccharide was classified as high-methoxyl pectin. The pectin turned into a gel by the generalised method.     

Separation and structure analysis of trisaccharide isomers produced from lactose by Lactobacillus bulgaricus L3 β-galactosidase

Using lactose as the substrate, galacto-oligosaccharides containing β-d-galactose residues were synthesised with β-galactosidase from Lactobacillus bulgaricus L3. The reaction mixture was fermented by yeast cells to consume the monosaccharides and disaccharides, and then it was fully acetylated in the presence of acetic anhydride under I₂ catalysis. Column chromatography of the resulting products, using ethyl acetate: petroleum ether as the eluent, generated two isomers of trisaccharide derivatives (I and II) in gram scale for the first time. Their structure characteristics were investigated by ESI-MS and NMR spectra. They were identified as (2,3,4,6-tetra-O-acetyl-d-galactopyranosyl)-β-(1 → 6)-(2,3,4-tri-O-acetyl-d-galactopyranosyl)-β-(1 → 4)-1,2,3,6-tetra-O-acetyl-α-d-glucopyranose (I) and (2,3,4,6-tetra-O-acetyl-d-galactopyranosyl)-β-(1 → 3)-(2,4,6-tri-O-acetyl-d-galactopyranosyl)-β-(1 → 4)-1,2,3,6-tetra-O-acetyl-α-d-glucopyranose (II), respectively. ESI-MS analysis of both deacetylated products of the two trisaccharide derivatives I and II revealed molecular ion peaks of free trisaccharides, which were structurally identified as Gal-β-(1 → 6)-Gal-β-(1 → 4)-Glc and Gal-β-(1 → 3)-Gal-β-(1 → 4)-Glc, respectively.     

Process development for mycelial growth and polysaccharide production in Tricholoma matsutake liquid culture

In this study, the effects of agitation and aeration on mycelial growth and exo-polysaccharide production were examined in batch cultures of Tricholoma matsutake. Agitation was varied from 100 to 300 rpm and aeration was varied from 0.5 to 1.5 vvm. Mycelial growth was 21.87 g/l at 150 rpm, and exo-polysaccharide production was 8.79 g/l at 1.5 vvm. When we analyzed the polysaccharide extractions from the cultured mycelium and the culture broth of T. matsutake, 1.4 g of crude polysaccharide was found per 100 g of dried weight in the cultured mycelium, and 1.47 g/l of polysaccharides was found in the culture broth. In addition, the amounts of β-Glucan in the soluble polysaccharide fractions of the cultured mycelium and culture broth were 75.4% and 83.6%, respectively. The cultured mycelium and the culture broth contained a higher amount of β-Glucan than that of the fruiting body.     

Lentinus edodes heterogalactan: Antinociceptive and anti-inflammatory effects

Cold aqueous extraction of basidiocarps (fruiting bodies) of the edible mushroom Lentinus edodes (shiitake) gave rise to a heteropolysaccharide, whose chemical structure, antinociceptive and anti-inflammatory properties were determined. Its chemical structure was based on monosaccharide composition, methylation analysis, and NMR spectroscopy (¹H, ¹³C, HSQC, HSQC-TOCSY, HSQC-NOESY, and coupled HMQC). It was found to be a fucomannogalactan with a main chain of (1 → 6)-linked α-d-galactopyranosyl units, partially substituted at O-2 by single-unit β-d-Manp or α-l-Fucp side chains. The polysaccharide produced a marked and dose-related effect when assessed against acetic acid-induced visceral nociception. Prevention of peritoneal capillary permeability and leukocyte infiltration caused by the acetic acid was similar in potency and effectiveness.