Characterization and immunomodulatory activities of polysaccharides from Spirogyra neglecta (Hassall) Kützing

Utilization of Macroalgae for the Production of Bioactive Compounds and Bioprocesses Using Microbial Biotechnology

To achieve sustainable development, alternative resources should replace conventional resources such as fossil fuels. In marine ecosystems, many macroalgae grow faster than terrestrial plants. Macroalgae are roughly classified as green, red, or brown algae based on their photosynthetic pigments. Brown algae are considered to be a source of physiologically active substances such as polyphenols. Furthermore, some macroalgae can capture approximately 10 times more carbon dioxide from the atmosphere than terrestrial plants. Therefore, they have immense potential for use in the environment. Recently, macroalgae have emerged as a biomass feedstock for bioethanol production owing to their low lignin content and applicability to biorefinery processes. Herein, we provided an overview of the bioconversion of macroalgae into bioactive substances and biofuels using microbial biotechnology, including engineered yeast designed using molecular display technology.

Search for evolutionary roots of land plant arabinogalactan-proteins in charophytes: presence of a rhamnogalactan-protein in Spirogyra pratensis (Zygnematophyceae)

Charophyte green algae (CGA) are assigned to be the closest relatives of land plants and therefore enlighten processes in the colonization of terrestrial habitats. For the transition from water to land, plants needed significant physiological and structural changes, as well as with regard to cell wall composition. Sequential extraction of cell walls of Nitellopsis obtusa (Charophyceae) and Spirogyra pratensis (Zygnematophyceae) offered a comparative overview on cell wall composition of late branching CGA. Because arabinogalactan-proteins (AGPs) are considered common for all land plant cell walls, we were interested in whether these special glycoproteins are present in CGA. Therefore, we investigated both species with regard to characteristic features of AGPs. In the cell wall of Nitellopsis, no hydroxyproline was present and no AGP was precipitable with the β-glucosyl Yariv's reagent (βGlcY). By contrast, βGlcY precipitation of the water-soluble cell wall fraction of Spirogyra yielded a glycoprotein fraction rich in hydroxyproline, indicating the presence of AGPs. Putative AGPs in the cell walls of non-conjugating Spirogyra filaments, especially in the area of transverse walls, were detected by staining with βGlcY. Labelling increased strongly in generative growth stages, especially during zygospore development. Investigations of the fine structure of the glycan part of βGlcY-precipitated molecules revealed that the galactan backbone resembled that of AGPs with 1,3- 1,6- and 1,3,6-linked Galp moieties. Araf was present only in small amounts and the terminating sugars consisted predominantly of pyranosidic terminal and 1,3-linked rhamnose residues. We introduce the term 'rhamnogalactan-protein' for this special AGP-modification present in S. pratensis.

Extraction, Structural Characterisation, and Immunomodulatory Properties of Edible Amanitahemibapha subspecies javanica (Corner and Bas) Mucilage Polysaccharide as a Potential of Functional Food

This research aimed to extract mucilage polysaccharides (MP) from Amanita hemibapha subspecies javanica (Corner and Bas), and further fractionate them using anion-exchange chromatography, yielding two fractions (MPF1 and MPF2). The crude extract, and fractions mainly consisted of carbohydrates (83.5-93.2%) with minor amounts of proteins (5.40-7.20%), and sulphates (1.40-9.30%). Determination of the monosaccharide composition revealed that glucose was the major unit, followed by galactose, mannose, rhamnose, and arabinose. The average molecular weight (MW) of the crude extract and fractions was in the range 104.0-479.4 × 103 g/mol. Interestingly, the crude extract, and fractions did not cause any toxic effect in RAW264.7 cells. However, they stimulated the RAW264.7 cells to release nitric oxide and cytokines through the activation of nuclear factor-kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) pathways via cell surface TLR4. Structural analysis of the most immunestimulating extract fraction, MPF2, revealed that the main backbone consisted of α-D-(1→6)-glucopyranoside. These results suggest that the MPs derived from A. hemibapha subspecies javanica (Corner and Bas) are potent in enhancing immunity; hence, they can be used as a functional ingredient in food products.

Effects of Spirogyra jaoensis as a dietary supplement on growth, pectoralis muscle performance, and small intestine morphology of broiler chickens

AIM

This study aimed to examine the effect of dietary Spirogyra jaoensis in starter feed on growth performance, pectoralis muscle (PM) growth, and small intestine morphology of broiler chickens.

MATERIALS AND METHODS

One hundred twenty one-day-old Cobb-500 broilers (body weight 46±2.6 g) were divided into four equal groups with 3 replicates in each group and given basal feed supplemented with dried S. jaoensis at doses of 0%, 0.5%, 1%, or 2%. The treatment was carried out until the chickens were 18 days old to examine growth of broiler chicks at starter period (8-21 days old).

RESULTS

Supplementation with S. jaoensis at doses of 0.5% and 1% resulted in increased weight and improved feed conversion ratio compared to the control group. At the end of treatment, chickens fed with 0.5% and 1% S. jaoensis weighed 428.3±47.8 g and 426.9±31.8 g, respectively, and were significantly heavier than the control group (373.1±44.1 g). Furthermore, parameters related to PM growth and small intestine morphology of chickens supplemented with 0.5% S. jaoensis in basal feed were improved compared to the control group.

CONCLUSION

The results of this research indicate that S. jaoensis at a dose of 0.5% improves growth performance, PM growth, and small intestine morphology in broiler chickens.

Immunomodulatory Activity of Low Molecular-Weight Peptides from Nibea japonica in RAW264.7 Cells via NF-κB Pathway

In this study, a low molecular-weight (Mw) peptide named NJP (<1 kDa), was purified from a protein hydrolysate of Nibea japonica by ultrafiltration, and its immunomodulatory effect on RAW264.7 cells was evaluated. The lactate dehydrogenase (LDH) and MTT assays were performed to explore the cytotoxicity of NJP. The results showed that NJP promoted cell proliferation and had no significant toxic effects on RAW264.7 cells. Moreover, the cells formed multiple pseudopodia indicating that they were in activated state. Further tests showed that NJP significantly promoted phagocytic capacity, and the secretion of proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). It also increased the synthesis of nitric oxide (NO) by upregulating inducible nitric oxide synthase (iNOS) protein level. Flow cytometry revealed that NJP promoted cell cycle progression and increased the percentage of cells in G0/G1 phase. NJP promoted IκBα degradation, p65 and nuclear factor (NF)-κB activation and translocation by up-regulating IKKα/β protein expression. In conclusion, these results indicated that NJP exerts immunomodulatory effects on RAW264.7 cells through the NF-κB signaling pathway. Therefore, NJP can be incorporated in the production of functional foods or nutraceuticals.

Caulerpa Cupressoides Var. Flabellata

Green seaweeds are rich sources of sulfated polysaccharides (SPs) with potential biomedical and nutraceutical applications. The aim of this work was to evaluate the immunostimulatory activity of SPs from the seaweed, Caulerpa cupressoides var. flabellata on murine RAW 264.7 macrophages. SPs were evaluated for their ability to modify cell viability and to stimulate the production of inflammatory mediators, such as nitric oxide (NO), intracellular reactive oxygen species (ROS), and cytokines. Additionally, their effect on inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) gene expression was investigated. The results showed that SPs were not cytotoxic and were able to increase in the production of NO, ROS and the cytokines, tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). It was also observed that treatment with SPs increased iNOS and COX-2 gene expression. Together, these results indicate that C. cupressoides var. flabellata SPs have strong immunostimulatory activity, with potential biomedical applications.

Effects of the molecular weight and protein and sulfate content of Chlorella ellipsoidea polysaccharides on their immunomodulatory activity

We investigated the effects of the protein and sulfate content, as well as the molecular weight (M_w), of green alga Chlorella ellipsoidea polysaccharides on their immunomodulatory activity. The deproteinized (DP_1-3), desulfated (DS_1-3), and hydrolyzed (DH_1-3) derivatives of C. ellipsoidea polysaccharides were prepared by enzymatic hydrolysis, desulfation, and acid hydrolysis, respectively, of differing durations, resulting in preparations containing various amounts of proteins (2.41%-8.97%), sulfates (1.36%-4.89%), and M_w (51.5-193.4kDa). The DH_1-3-induced production of nitric oxide (NO) by RAW264.7 cells, decreased as the M_w of DH_1-3 decreased. In addition, the sulfate content and M_w of DS_1-3 affected the release of NO. However, lower protein content did not affect DP_1-3-induced NO release and cytokine mRNA expression in RAW264.7 cells. Based on a multiple regression analysis of the effects of protein content, sulfate content, and M_w, on NO release, we found that M_w was a key factor for the stimulation of RAW264.7 cells, as it affected cytokine production, and activation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. Therefore, the M_w of C. ellipsoidea polysaccharides played an important role in their immunomodulatory activities.

Effect of Spirogyra neglecta on the early stages of 1, 2-dimethylhydrazine-induced colon carcinogenesis in rats

This study focused on the chemopreventive effects of Spirogyra neglecta extract (SNE) and dried S. neglecta mixed diet on the early stages of 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats. Male Wistar rats were injected with DMH to initiate aberrant crypt foci (ACF) formation. In the initiation stage, SNE significantly decreased the number of ACF in the colon of DMH-treated rats. Rats that received a low dose of SNE showed enhanced activity of several detoxifying and antioxidant enzymes. In the postinitiation stage, a low dose of SNE significantly decreased the number of ACF in the colon of DMH-treated rats. It significantly reduced the number of proliferating cell nuclear antigen-positive cells and increased the number of apoptotic cells in colonic crypts. S. neglecta thus inhibited the development of the early stages of DMH-induced colon carcinogenesis in rats by modulation of xenobiotic metabolizing enzymes and inhibition of cell proliferation as well as induction of apoptosis.

RAW264.7 Cell Activating Glucomannans Extracted from Rhizome of Polygonatum sibiricum

Water-soluble polysaccharides isolated from the rhizome of Polygonatum sibiricum and fractionated using ion-exchange chromatography were investigated to determine their structure and immunostimulating activity. Crude and fractions (F₁ and F₂) consisted of carbohydrates (85.1~88.3%) with proteins (4.51~11.9%) and uronic acid (1.79~7.47%), and included different levels of mannose (62.3~76.3%), glucose (15.2~20.3%), galactose (4.35~15.3%), and arabinose (4.00~7.65%). The crude contained two peaks with molecular weights (Mw) of 151×10³ and 31.8×10³, but F₁ and F₂ exhibited one major peak with Mw of 103×10³ and 628×10³, respectively. Little immunostimulatory activity was observed by the crude; however, F₁ and F₂ significantly activated RAW264.7 cells to release nitric oxide and various cytokines, suggesting they were potent immunostimulators. The backbone of the most immunostimulating fraction (F₁) was (1→4)-manno- and (1→4)-gluco-pyranosyl residues with galactose and glucose attached to O-6 of manno-pyranoside.

Spirogyra neglecta inhibits the absorption and synthesis of cholesterol in vitro

Background

Spirogyra neglecta (SN) has many nutritional benefits and it is commonly used to ameliorate different human conditions including inflammation, gastric ulcer, hyperglycemia, and hyperlipidemia. However, the mechanism of the hypocholesterolemic effect of SN still remains unclear. Therefore, the present study was aimed to evaluate the effect of SN extract particularly on cholesterol absorption and synthesis mechanisms.

Methods

For cholesterol absorption, the uptake of cholesterol was measured by using tritium radiolabeling of cholesterol in Caco-2 cells. Bile acid binding, micelles size, and cholesterol solubility were analyzed in in vitro assays, while cholesterol synthesis was evaluated by using a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase assay kit.

Results

SN extract was found to decrease cholesterol uptake in Caco-2 cells and decreased the solubility of cholesterol in micelles. The SN extract bound to taurocholate, taurodeoxycholate, and glycodeoxycholate bile acids, and increased micelles size. SN has also demonstrated an inhibitory effect on HMG-CoA reductase (HMGR) enzymatic activity. For further experimentation, the treatment combination of SN and ezetimibe (0.04 mg/mL) showed a greater significant reduction in cholesterol uptake than the extract alone.

Conclusion

These observations suggested that inhibitory cholesterol absorption effects of SN could be mediated through the modulation of size and solubility of cholesterol micelles, resulting in interference of cholesterol uptake. In addition, SN inhibited the rate limiting step of cholesterol synthesis. This study provides supporting evidence for the potential usage of SN as a cholesterol lowering agent.