Jian-Yong Wu

Recent advances in Cordyceps sinensis polysaccharides : mycelial fermentation, isolation, structure, and bioactivities: A review

n Abstractn n n Cordyceps (Ophiocordyceps sinensis) sinensis, the Chinese caterpillar fungus, is a unique and precious medicinal fungus in traditional Chinese medicine which has been used as a prestigious tonic and therapeutic herb in China for centuries. Polysaccharides are bioactive constituents of C. sinensis, exhibiting several activities such as immunomodulation, antitumour, antioxidant and hypoglycaemic. As natural C. sinensis fruiting body-caterpillar complexes are very rare and expensive, the polysaccharides documented over the last 15–20years from this fungal species were mostly extracted from cultivated fungal mycelia (intracellular polysaccharides) or from mycelial fermentation broth (exopolysaccharides). Extraction and purification of the polysaccharides is a tedious process involving numerous steps of liquid and solid phase separations. Nevertheless, a large number of polysaccharide structures have been purified and elucidated. However, relationships between the structures and activities of these polysaccharides are not well established. This review provides a comprehensive summary of the most recent developments in various aspects (i.e., production, extraction, structure, and bioactivity) of the intracellular and exopolysaccharides from mycelial fermentation of C. sinensis fungi. The contents and data will serve as useful references for further investigation, production and application of these polysaccharides in functional foods and therapeutic agents.n n

Effective Elicitors and Process Strategies for Enhancement of Secondary Metabolite Production in Hairy Root Cultures

This chapter reviews the various biotic and abiotic elicitors applied to hairy root cultures and their stimulating effects on the accumulation of secondary metabolites. Elicitors generally refer to the agents that stimulate the defense responses of plants. As a major response of plants to biotic and abiotic stress, the accumulation of secondary metabolites in plant tissue cultures can be stimulated by the elicitors. Among the many elicitors applied to hairy root cultures as well as plant cell suspension cultures, the most common and effective elicitors are fungal cell extracts, polysaccharides from fungal and plant cells, and heavy metal salts. With the crude fungal cell extracts, it is essential to observe the preparation conditions carefully for achieving reproducible effects. In addition to the chemical agents, UV-radiation, hyperosmotic stress and temperature shift have been shown effective for some plant species/metabolites. Elicitor type, dose, and treatment schedule are major factors determining the effects on the secondary metabolite production. In addition to the accumulation of products in roots, elicitor treatments often stimulate the release of intracellular products. Although elicitation is mainly effective to increase specific product yield on per unit mass of roots, the incorporation of nutrient feeding strategies can be applied to enhance the volumetric product yield. The integration of in situ product recovery from the roots/liquid medium is another synergistic strategy with the elicitor treatment to improve the process.

Molecular properties and antioxidant activities of polysaccharides isolated from alkaline extract of wild Armillaria ostoyae mushrooms

This study aims to discover novel and bioactive polysaccharides (PS) from wild Armillaria ostoyae, a honey mushroom species. Two PS designated AkPS1V-1 (66.6 kDa) and AkPS1V-2 (15.3 kDa) were isolated and fractionated by anion ion exchange (IEC) and size exclusion chromatography (SEC) from the alkaline extract of A. ostoyae mushrooms. AkPS1V-1 was a glucan composed of solely glucose residues and AkPS1V-2 a heteropolysaccharide composed of glucose and galactose at 6:1 molar ratio. AkPS1V-2 exhibited higher antioxidant activities than AkPS1V-1 based on reducing power, radical scavenging and metal chelating assays. The structure of AkPS1V-2 was further analyzed and elucidated as a branched galactoglucan with a backbone composed of (1→6)-β-D-glucopyranosyl, (1→3)-β-D-glucopyranosyl, (1→3)-α-D-galactopyranosyl and (1→3,6)-β-D-glucopyranosyl residues at 3:1:1:1 ratio, and side chain of (1→3)-β-D-glucopyranosyl residue. This is the first report on a pure PS structure and its antioxidant activities from this mushroom species.

Biocompatible Polyelectrolyte Complex Nanoparticles from Lactoferrin and Pectin as Potential Vehicles for Antioxidative Curcumin

Polyelectrolyte complex nanoparticles (PEC NPs) were fabricated via electrostatic interactions between positively charged heat-denatured lactoferrin (LF) particles and negatively charged pectin. The obtained PEC NPs were then utilized as curcumin carriers. PEC NPs were prepared by mixing 1.0 mg/mL solutions of heat-denatured LF and pectin at a mass ratio of 1:1 (w/w) in the absence of NaCl at pH 4.50. PEC NPs that were prepared under optimized conditions were spherical in shape with a particle size of ∼208 nm and zeta potential of ∼-32 mV. Hydrophobic curcumin was successfully encapsulated into LF/pectin PEC NPs with high encapsulation efficiency (∼85.3%) and loading content (∼13.4%). The in vitro controlled release and prominent antioxidant activities of curcumin from LF/pectin PEC NPs were observed. The present work provides a facile and fast method to synthesize nanoscale food-grade delivery systems for the improved water solubility, controlled release, and antioxidant activity of hydrophobic curcumin.

Protective effects of natural and partially degraded konjac glucomannan on Bifidobacteria against antibiotic damage

This study was to evaluate the protective effects of a dietary fiber, konjac glucomannan (KGM) from the plant tuber of Amorphohallus konjac on Bifidobacteria against antibiotic damage. KGM (∼8.8×108Da) was partially degraded with high-intensity ultrasound to KGM-US (∼1.8×106Da) and then hydrolyzed with trifluoroacetic acid (TFA) to KGM-AH (1369Da). KGM-US (at 5g/l) showed the most significant protective effect on most bifidobacterial strains against penicillin and streptomycin inhibition, increasing the minimal inhibitory and bactericidal concentration (MIC and MBC) dramatically, and KGM also showed significant effects on enhancing the MBC of enrofloxacin, penicillin, tetracycline and streptomycin. In addition, the adsorbance ability and biofilm formation effects of KGM and degraded KGM products may be partially responsible for the protective effects. The results suggested that natural KGM and ultrasound treated KGM have protective effects for the human gut probiotic bacteria against the damage caused by specific antibiotics.

Antifatigue Functions and Mechanisms of Edible and Medicinal Mushrooms

Fatigue is the symptom of tiredness caused by physical and/or psychological stresses. As fatigue is becoming a serious problem in the modern society affecting human health, work efficiency, and quality of life, effective antifatigue remedies other than pharmacological drugs or therapies are highly needed. Mushrooms have been widely used as health foods, because of their various bioactive constituents such as polysaccharides, proteins, vitamins, minerals, and dietary fiber. This paper reviews the major findings from previous studies on the antifatigue effects, the active components of mushrooms, and the possible mechanisms. Many studies have demonstrated the antifatigue effects of edible and medicinal mushrooms. These mushrooms probably mitigate human fatigue through effects on the functional systems, including the muscular, cardiovascular, hormone, and immune system. The bioactive constituents that contribute to the antifatigue effects of mushrooms may include polysaccharides, peptides, nucleosides, phenolic compounds, and triterpenoids. Further research is still needed to identify the active ingredients and to investigate their mechanism of action on the antifatigue effects. Since most previous studies have been carried out in animal models, more human trials should be performed to verify the antifatigue function of edible and medicinal mushrooms.

The Study on Paraffin-Water Emulsion PCM with Low Supercooling Degree

This study aims to develop paraffin waxes based phase change material emulsion with low supercooling degree, which can be applied in a Thermal Energy Storage (TES) systems to maximize the use of natural heating and cooling sources via solar thermal collectors or evaporative coolers, and to raise the energy efficiency of the chillers operating at off-peak period. In this study, a kind of hexadecane-water emulsion with small droplet size was prepared and analyzed. The modified Multi-Wall Carbon Nano-Tube (MWCNT) particles were dispersed in emulsion as the nucleating agent to reduce supercooling degree. The MWCNT particles were modified with strong acids H2SO4 and HNO3 to increase the compatibility with the organic liquid. Thermal analysis of the hexadecane-water emulsions with well-dispersed MWCNT particles by Differential Scanning Calorimeter (DSC) indicated that the supercooling degree of emulsion was significantly decreased. The effective ranges of nucleating agent concentration were summarized which provided a promising way of improving the performance of system energy efficiency in TES systems.

The Application of Modified Multi-Wall Carbon Nano-Tube Particles in PCM as the Nucleating Agent

Paraffin waxes as the phase change materials (PCM) usually tend to become supercooled in their crystallization processes, which limits their applications. As a solution, the modified multi-wall carbon nanotube (MWCNT) particles were dispersed in PCM as the nucleating agent to effectively reduce the super cooling, oxidized by strong acids H2SO4 and HNO3 to increase the compatibility with the organic liquid. In this study, the n-hexadecane-1-decanol slurry with modified MWCNT in different concentration was prepared and analyzed. Thermal analysis by differential scanning calorimeter (DSC) indicated that the super cooling of PCM was significantly decreased. The effective ranges of nucleating agent concentration were summarized which provided a promising way of improving the performance of system energy efficiency in building cooling and heating applications.

Bifidogenic effects of Cordyceps sinensis fungal exopolysaccharide and konjac glucomannan after ultrasound and acid degradation

The bifidogenic effects of exopolysaccharide (EPS) of a medicinal fungus (Cordyceps sinensis) and a well-known food polysaccharide konjac glucomannan (KGM) with different molecular weight (MW) ranges were evaluated through in vitro experiments in liquid cultures of Bifidobacteria. Native EPS and KGM were partially degraded with power ultrasound (US) to improve the water solubility, and further hydrolysed with trifluoroacetic acid to much lower MW. The acid-hydrolysed fractions (EPS-AH and KGM-AH) supported the growth of all five tested bifidobacterial species, while the US-degraded high MW fractions, EPS-US and KGM-US, could only slightly support the growth of some species. All EPS fractions increased the acetic acid production of most bifidobacterial species. Most remarkably, the high MW EPS-US, EPS-AH and KGM-US fractions significantly enhanced the cell viability with much higher colony forming unit (CFU) counts, suggesting a protective effect of these high MW polysaccharides for the bacterial survival. The results have shown that MW was a significant factor on the bifidogenic properties of partially degraded EPS and KGM.

Improving the water solubility of Monascus pigments under acidic conditions with gum arabic

BACKGROUNDnMonascus pigments (Mps) are natural food colorants and their stability in acidic solutions is important for application in the food industry. This study aimed to evaluate the use of gum arabic (GA) as a stabilizer for maintaining the solubility of Mps in an acidic aqueous solution exposed to a high temperature, and to analyze the molecular interactions between GA and Mps.nnnRESULTSnMps dispersed (0.2 g kg-1 ) in deionized water at pH 3.0-4.0 without GA formed precipitates but remained in a stable solution in the presence of GA (1 g kg-1 ). The significant improvement of Mps water solubility under acidic conditions was attributed to the formation of Mps-GA complexes, as indicated by a sharp increase in the fluorescence intensity. The results on particle size, zeta potential, and transmission electron microscopy further suggested that molecular binding of Mps to GA, electrostatic repulsion, and steric hindrance of GA were contributing factors to preventing the aggregation of Mps in acidic solutions. A mechanistic model was presented for GA-Mps interactions and complex structures.nnnCONCLUSIONnGA was proven to be an effective stabilizer of natural food colorants in acidic solutions.