Isolation, structures and biological activities of polysaccharides from Chlorella: A review

Synthesis of polysaccharides by microalgae Chlorella sp

Microalgae are known to be the richest natural source of polysaccharides. The study aimed to evaluate the ability of microalgae from the Chlorella sp. genus to synthesize polysaccharides. Brody & Emerson max medium proved to be the most effective; the average cell content in the culture fluid at the beginning and at the end of cultivation for IPPAS Chlorella pyrenoidosa Chick was 1.23 ± 0.03 g/L and 1.71 ± 0.20 g/L, respectively. With a high average dry weight of IPPAS Chlorella pyrenoidosa Chick (4.45 ± 0.10 g/L), it produced the least amount of neutral sugars (0.75 ± 0.02 g/L) and uronic acids (0.14 ± 0.01 mg/L). The microalga IPPAS Chlorella vulgaris with the lowest average dry weight (1.18 ± 0.03 g/L) produced 0.80 ± 0.02 g/L of neutral sugars and 0.17 ± 0.01 mg/L of uronic acids. Microalgal polysaccharides have the potential to be used as a source for biologically active food additives, as they contain various types of polysaccharides that can be beneficial to human health.

Extraction, structural characterization, and antioxidant activity of polysaccharides from three microalgae

Microalgal polysaccharides have received much attention due to their potential value in preventing and regulating oxidative damage. This study aims to reveal the mechanisms of regulating oxidative stress and the differences in the yield, structure, and effect of polysaccharides extracted from three microalgae: Golenkinia sp. polysaccharides (GPS), Chlorella sorokiniana polysaccharides (CPS), and Spirulina subsalsa polysaccharides (SPS). Using the same extraction method, GPS, CPS, and SPS were all heteropoly- saccharides composed of small molecular fraction: the monosaccharides mainly comprised galactose (Gal). Among the three, SPS had a higher proportion of small molecular fraction, and a higher proportion of Gal; thus it had the highest yield and antioxidant activity. GPS, CPS, and SPS all showed strong antioxidant activity in vitro, and showed strong ability to regulate oxidative stress, among which SPS was slightly higher. From the analysis of gene expression, the Nrf2-ARE signalling pathway was an important pathway for GPS, CPS, and SPS to regulate cellular oxidative stress. This study provides a theoretical foundation for further research on the utilization of microalgae polysaccharides and product development.

Emerging trends and challenges in polysaccharide derived materials for wound care applications: A review

Polysaccharides are favourable and promising biopolymers for wound care applications due to their abundant natural availability, low cost and excellent biocompatibility. They possess different functional groups, such as carboxylic, hydroxyl and amino, and can easily be modified to obtain the desirable properties and various forms. This review systematically analyses the recent progress in polysaccharides derived materials for wound care applications, emphasizing the most commonly used cellulose, chitosan, alginate, starch, dextran and hyaluronic acid derived materials. The distinctive attributes of each polysaccharide derived wound care material are discussed in detail, along with their different forms, i.e., films, membranes, sponges, nanoemulsions, nanofibers, scaffolds, nanocomposites and hydrogels. The processing methods to develop polysaccharides derived wound care materials are also summarized. In the end, challenges related to polysaccharides derived materials in wound care management are listed, and suggestions are given to expand their utilization in the future to compete with conventional wound healing materials.

Extraction, purification, structural characteristics, bioactivity and potential applications of polysaccharides from Semen Coicis: A review

Semen Coicis (S. Coicis) has been regarded as a valuable source of traditional herbal medicine in China for thousands of years. S. Coicis polysaccharides (SCPs) are one of the most important bioactive ingredients of S. Coicis, which have attracted worldwide attention, because of their great marketing potential and development prospects. Hot water extraction is currently the most commonly used method to isolate SCPs. The structural characteristics of SCPs have been extensively investigated through various advanced modern analytical techniques to dissect the structure-activity relationships. SCPs are mainly composed of diverse monosaccharides, from which Rha and Ara are the most prevalent glycosyl groups. In addition, the structures of SCPs are found to be closely related to their multiple biological activities, including antioxidant activity, immunomodulatory function, antitumor activity, hypoglycemic effect, intestinal microbiota regulatory activity, anti-inflammatory activity, among others. In view of this, this review aimed to provide systematic and current information on the isolation, structural characteristics, and bioactivities of SCPs to support their future applications as therapeutic agents and functional foods.

Structural characterization of a Chlorella heteropolysaccharide by analyzing its depolymerized product and finding an inducer of human dendritic cell maturation

Chlorella polysaccharides have been gaining increasing attention because of their high yield from dried Chlorella powder and their remarkable immunomodulatory activity. In this study, the major polysaccharide fraction, CPP-3a, in Chlorella pyrenoidosa, was isolated, and its detailed structure was investigated by analyzing the low-molecular-weight product prepared via free radical depolymerization. The results indicated that CPP-3a with a molecular weight of 195.2 kDa was formed by →2)-α-L-Araf-(1→, →2)-α-D-Rhap-(1→, →5)-α-L-Araf-(1→, →3)-β-D-Glcp-(1→, →4)-α-D-Glcp-(1→, →4)-α-D-GlcpA-(1→, →2,3)-α-D-Manp-(1→, →3,4)-α-D-Manp-(1→, →3,4)-β-D-Galp-(1→, →3,6)-β-D-Galp-(1→, and →2,3,6)-α-D-Galp-(1→ residues, branched at C2, C3, C4, or C6 of α/β-D-Galp and α-D-Manp, and terminated by α/β-L-Araf, α-L-Arap, α-D-Galp, and β-D-Glcp. Biological assays showed that CPP-3a significantly altered the dendritic morphology of immature dendritic cells (DCs). Enhanced CD80, CD86, and MHC I expression on the cell surface and decreased phagocytic ability indicated that CPP-3a could induce the maturation of DCs. Furthermore, CPP-3a-stimulated DCs not only stimulated the proliferation of allogeneic naïve CD4+ T cells and the secretion of IFN-γ, but also directly stimulated the activation and proliferation of CD8+ T cells through cross-antigen presentation. These findings indicate that CPP-3a can promote human DC maturation and T-cell stimulation and may be a novel DC maturation inducer with potential developmental value in DC immunotherapy.

Anti-Vasculogenic, Antioxidant, and Anti-Inflammatory Activities of Sulfated Polysaccharide Derived from Codium tomentosum: Pharmacokinetic Assay

The purpose of this paper was to investigate the anti-inflammatory and anti-angiogenic activities of sulfated polysaccharide from C. tomentosum (PCT) using carrageenan (CARR)-induced paw edema in a rat model and anti-vasculogenic activity on a chorioallantoic membrane assay (CAM) model. Based on in vitro tests of anti-radical, total antioxidant, and reducing power activities, PCT presents a real interest via its antioxidant activity and ability to scavenge radical species. The in vivo pharmacological tests suggest that PCT possesses anti-inflammatory action by reducing paw edema and leukocyte migration, maintaining the redox equilibrium, and stabilizing the cellular level of several pro-/antioxidant system markers. It could significantly decrease the malondialdehyde levels and increase superoxide dismutase, glutathione peroxidase, and glutathione activities in local paw edema and erythrocytes during the acute inflammatory reaction of CARR. PCT pretreatment was effective against DNA alterations in the blood lymphocytes of inflamed rats and reduced the hematological alteration by restoring blood parameters to normal levels. The anti-angiogenic activity results revealed that CAM neovascularization, defined as the formation of new vessel numbers and branching patterns, was decreased by PCT in a dose-dependent manner, which supported the in silico bioavailability and pharmacokinetic findings. These results indicated the therapeutic effects of polysaccharides from C. tomentosum and their possible use as anti-proliferative molecules based on their antioxidant, anti-inflammatory, and anti-angiogenic activities.

A sulfated exopolysaccharide derived from Chlorella sp. exhibiting in vitro anti-α-D-Glucosidase activity

There is a great scientific curiosity to discover all environments sheltering microalgae, especially those with exceptional characteristics from coldest to hottest ones, the purpose remains to explore the potential of the native microalgae flora and the research for new bioactive compounds. This study aimed to isolate a polysaccharide-producing microalga from an extreme ecosystem and to evaluate its capacity to inhibit the α-D-glucosidase enzyme. Chlorella strain is isolated from hypersaline Lake in the Algerian desert. The exopolysaccharide extraction was performed by the concentration of free-cell supernatant in a rotary evaporator. The infrared analysis showed a characteristic footprint of carbohydrates with particular functional groups, such as sulfate. Gas chromatography-mass spectrometry has revealed a hetero-exopolysaccharide composed of galactose 35.75%, glucose 21.13%, xylose 16.81%, fructose 6.96%, arabinose 5.10%, and glucuronic acid 2.68%. The evaluation of the anti-hyperglycemic activity demonstrated a significant α-D-glucosidase inhibition of 80.94 ± 0.01% at 10 mg mL-1 with IC50 equal to 4.31 ± 0.20 mg mL-1. This study opens a vast prospect to use exopolysaccharides as natural nutraceutical or food additive.

XQZ3, a Chlorella pyrenoidosa polysaccharide suppresses cancer progression by restraining mitochondrial bioenergetics via HSP90/AKT signaling pathway

The mitochondria are known to exert significant influence on various aspects of cancer cell physiology. The suppression of mitochondrial function represents a novel avenue for the advancement of anti-cancer pharmaceuticals. The heat shock protein HSP90 functions as a versatile regulator of mitochondrial metabolism in cancer cells, rendering as a promising target for anticancer interventions. In this work, a novel acid polysaccharide named as XQZ3 was extracted from Chlorella pyrenoidosa and purified by DEAE-cellulose and gel-filtration chromatography. The structural characteristic of XQZ3 was evaluated by monosaccharides composition, methylation analysis, TEM, FT-IR, and 2D-NMR. It was found that XQZ3 with a molecular weight of 29.13 kDa was a complex branched polysaccharide with a backbone mainly composed of galactose and mannose. It exhibited good antitumor activity in vitro and in vivo by patient-derived 3D organoid models and patient-derived xenografts models. The mechanistic investigations revealed that XQZ3 specifically interacted with HSP90, impeding the activation of the HSP90/AKT/mTOR signaling cascade. This, in turn, led to the induction of mitochondrial dysfunction, autophagy, and apoptosis, ultimately resulting in the demise of cancer cells due to nutrient deprivation. This study offers a comprehensive theoretical foundation for the advancement of XQZ3, a novel polysaccharide inhibitor targeting HSP90, with potential as an effective therapeutic agent against cancer.

Structure of a polysaccharide MDP2-1 from Melastoma dodecandrum Lour. and its anti-inflammatory effects

The anti-inflammatory activity of polysaccharides derived from Melastoma dodecandrum Lour. was evaluated in pyretic mice and HEK-Blue™ hTLR4 cells. The testing led to the identification of MDP2-1, which was then investigated for its structural characteristics and anti-inflammatory effects. Results showed that MDP2-1 had a molecular weight of 29.234 kDa and primarily consisted of galactose, arabinose, rhamnose, glucose, glucuronic acid, and galacturonic acid. Its main backbone was composed of →4)-α-D-GalpA-(1→, →2)-α-L-Rhap-(1→, →3,4)-α-D-GalpA-(1→, →2,4)-α-D-GlcpA-(1→, and its side chains were connected by →4)-α-D-Galp-(1→, α-D-Galp-(1→, →4)-β-D-Glcp-(1→, and α-L-Araf-(1→. In vivo experiments on mice demonstrated that MDP2-1 attenuated LPS-induced acute lung injury, and in vitro experiments on RAW264.7 cells showed that MDP2-1 reduced the levels of inflammatory mediators and mitigated LPS-induced inflammatory damage by inhibiting the activation of the TLR4 downstream NF-κB/MAPK pathway. These findings suggest that MDP2-1 is a novel anti-inflammatory agent for therapeutic interventions.

Heterotrophic Selenium Incorporation into Chlorella vulgaris K-01: Selenium Tolerance, Assimilation, and Removal through Microalgal Cells

Chlorella has been applied in the production of selenium (Se) enriched organic biomass. However, limited information exists regarding heterotrophic selenium tolerance and its incorporation into Chlorella. This study aimed to investigate the potential of using Chlorella vulgaris K-01 for selenium biotransformation. To assess the dose-response effect of Se stress on the strain, time-series growth curves were recorded, growth productivity parameters were calculated, and Gaussian process (GP) regression analysis was performed. The strain's carbon and energy metabolism were evaluated by measuring residual glucose in the medium. Characterization of different forms of intracellular Se and residual Se in the medium was conducted using inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometer (ICP-OES). The EC50 value for the strain in response to Se stress was 38.08 mg/L. The maximum biomass productivity was 0.26 g/L/d. GP regression analysis revealed that low-level Se treatment could increase the biomass accumulation and the carrying capacity of Chlorella vulgaris K-01 in a heterotrophic culture. The maximum organic Se in biomass was 154.00 μg/g DW. These findings lay the groundwork for understanding heterotrophic microalgal production of Se-containing nutraceuticals, offering valuable insights into Se tolerance, growth dynamics, and metabolic responses in Chlorella vulgaris K-01.

Physicochemical characterization, digestion profile and gut microbiota regulation activity of intracellular polysaccharides from Chlorella zofingiensis

A number of studies have shown that the polysaccharides from microalgae exhibit diverse biological activities, however, little is known about their digestibility and impact on human gut microbiota. In this study, a simulating digestion and fermentation system were established to investigate the digestibility and fermentation of intracellular polysaccharides from Chlorella zofingiensis (CZIP-S3). The results indicated that CZIP-S3 is a macromolecular polysaccharide composed of mannose, glucose, galactose and rhamnose, consisting of a main chain and two branched repeating units. CZIP-S3 could not be digested in the upper gastrointestinal tract. However, CZIP-S3 could be metabolized into smaller molecules by the gut microbiota. The pH values continuously decrease during fermentation, whereas, the amount of short-chain fatty acids steadily increase. Furthermore, CZIP-S3 could modulate the composition of gut microbiota, via lowering the ratio of Firmicutes/Bacteroidetes and increasing the relative abundance of Bacteroides, Bifidobacterium and Akkermansia. The data suggested that CZIP-S3 could potentially be used as an ingredient for functional foods or prebiotics to improve human health by promoting the relative abundances of beneficial bacteria.

Nutritional Supplements for Skin Health-A Review of What Should Be Chosen and Why

Supplementation of micronutrients is considered to be crucial in the reinforcement of the skin's barrier. In this paper, 14 nutritional compounds commonly used in food or pharmaceutic industries were analyzed in terms of influencing skin conditions. The major objective of this paper was to provide a narrative review of the available literature regarding several chosen compounds that are currently widely recommended as supplements that aim to maintain proper and healthy skin conditions. We conducted a review of the literature from PubMed, Scopus, and Web of Science until September 2023 without any other restrictions regarding the year of the publication. Ultimately, we reviewed 238 articles, including them in this review. Each of the reviewed compounds, including vitamin A, vitamin C, vitamin D, vitamin E, curcumin, chlorella, Omega-3, biotin,Ppolypodium leucotomos, Simmondsia chinesis, gamma oryzanol, olive leaf extract, spirulina, and astaxanthin, was observed to present some possible effects with promising benefits for a skin condition, i.e., photoprotective radiation. Adding them to the diet or daily routine might have a positive influence on some skin inflammatory diseases such as atopic dermatitis or psoriasis. Further, UV radiation protection facilitated by some supplements and their impact on human cells might be helpful during chemotherapy or in preventing melanoma development. Further research is needed because of the lack of clear consensus regarding the doses of the described compounds that could provide desirable effects on the skin.

The Antioxidant and Anti-Complementary Activities of Crude Polysaccharides from Trifoliate Orange (Poncirus trifoliate) Seeds

In this study, I extracted the crude polysaccharides from trifoliate orange (Poncirus trifoliate) seeds, known as TSCP, using water extraction and ethanol precipitation. The monosaccharide composition of TSCP was in the following order: arabinose (28.28 mol%)> galactose (16.76 mol%)> galacturonic acid+glucuronic acid (13.6 mol%)> glucose (12.45 mol%)> rhamnose (4.18 mol%)> mannose (0.57 mol%)> fucose (0.32 mol%). Its total polyphenol contents were 28.66 and 70.96 μg/mL at 1 and 10 mg/mL, respectively (P<0.01). Further, the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity of 10 mg/mL TSCP (31.67%) was higher than that of 1 mg/mL TSCP (8.07%; P<0.01) and also higher than its 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (11.97%) at the same concentration (10 mg/mL; P<0.01). The anti-complementary property of TSCP increased in a concentration-dependent manner (P<0.001), and at 1,000 μg/mL, it was comparable (61.36%) to the positive control (60%) consisting of polysaccharide-K. In conclusion, TSCP might be a potential immune modulator.

A regular Chlorella mannogalactan and its sulfated derivative as a promising anticoagulant: Structural characterization and anticoagulant activity

Chlorella is one of the most widely cultivated species of microalgae and has been consumed as a "green healthy food". In this study, a novel polysaccharide (CPP-1) was isolated from Chlorella pyrenoidosa, structurally analyzed, and sulfated as a promising anticoagulant. Structural analyses by chemical and instrumental methods such as monosaccharide composition, methylation-GC-MS and 1D/2D NMR spectroscopy analysis revealed that CPP-1 had a molecular weight of ~13.6 kDa, and mainly consisted of d-mannopyranose (d-Manp), 3-O-methylated d-Manp (3-O-Me-d-Manp), and d-galactopyranose (d-Galp). The molar ratio of d-Manp and d-Galp was 1.0:2.3. CPP-1 consisted of a (1→6)-linked β-d-Galp backbone substituted at C-3 by the d-Manp and 3-O-Me-d-Manp residues in a molar ratio of 1:1, which was a regular mannogalactan. The sulfated Chlorella mannogalactan (SCM) with sulfated group content of 40.2 % equivalent to that of unfractionated heparin was prepared and analyzed. NMR analysis confirmed its structure, indicating that most free hydroxyl groups in the side chains and partial hydroxyl groups in the backbone were sulfated. Anticoagulant activity assays indicated that SCM exhibited strong anticoagulant activity by inhibiting intrinsic tenase (FXase) with IC₅₀ of 13.65 ng/mL, which may be a safer anticoagulant as an alternative to heparin-like drugs.

Emerging Applications of Chlorella sp. and Spirulina (Arthrospira) sp

Chlorella sp. and Spirulina (Arthrospira) sp. account for over 90% of the global microalgal biomass production and represent one of the most promising aquiculture bioeconomy systems. These microorganisms have been widely recognized for their nutritional and therapeutic properties; therefore, a significant growth of their market is expected, especially in the nutraceutical, food, and beverage segments. However, recent advancements in biotechnology and environmental science have led to the emergence of new applications for these microorganisms. This paper aims to explore these innovative applications, while shedding light on their roles in sustainable development, health, and industry. From this state-of-the art review, it was possible to give an in-depth outlook on the environmental sustainability of Chlorella sp. and Spirulina (Arthrospira) sp. For instance, there have been a variety of studies reported on the use of these two microorganisms for wastewater treatment and biofuel production, contributing to climate change mitigation efforts. Moreover, in the health sector, the richness of these microalgae in photosynthetic pigments and bioactive compounds, along with their oxygen-releasing capacity, are being harnessed in the development of new drugs, wound-healing dressings, photosensitizers for photodynamic therapy, tissue engineering, and anticancer treatments. Furthermore, in the industrial sector, Chlorella sp. and Spirulina (Arthrospira) sp. are being used in the production of biopolymers, fuel cells, and photovoltaic technologies. These innovative applications might bring different outlets for microalgae valorization, enhancing their potential, since the microalgae sector presents issues such as the high production costs. Thus, further research is highly needed to fully explore their benefits and potential applications in various sectors.

Regulatory mechanism of high-concentration CO2 on polysaccharide accumulation in Tetradesmus obliquus cultured in sludge extract

Microalgae such as Tetradesmus obliquus have great potential in immobilizing high-concentration CO₂ and removing highly toxic organic matters, which could be produced from coal chemical industry and coal chemical wastewater biological treatment process. In this study, Tetradesmus obliquus was cultured in sludge extract and high-concentration CO₂ was added. The maximum cell density and dry weight were respectively (111.46 ± 4.87) × 10⁶ cell/mL and 3.365 ± 0.168 g/L under 30% CO₂. Tetradesmus obliquus accumulated the most polysaccharides (629.60 ± 31.48 mg/L) on the 30th day under 30% CO₂. The results of proteomic showed that the upregulation of A0A2Z4THB7 and A0A383VAT1 promoted polysaccharide accumulation. Polysaccharide was mainly formed at the stable phase instead of the log-growth phase due to the abiotic stress caused by high TOC at the log-growth phase. Collectively, this study revealed the regulatory mechanism of high-concentration CO₂ on the toxicity removal and accumulation of polysaccharides in Tetradesmus obliquus.

Bioactivity of Macronutrients from Chlorella in Physical Exercise

Chlorella is a marine microalga rich in proteins and containing all the essential amino acids. Chlorella also contains fiber and other polysaccharides, as well as polyunsaturated fatty acids such as linoleic acid and alpha-linolenic acid. The proportion of the different macronutrients in Chlorella can be modulated by altering the conditions in which it is cultured. The bioactivities of these macronutrients make Chlorella a good candidate food to include in regular diets or as the basis of dietary supplements in exercise-related nutrition both for recreational exercisers and professional athletes. This paper reviews current knowledge of the effects of the macronutrients in Chlorella on physical exercise, specifically their impact on performance and recovery. In general, consuming Chlorella improves both anaerobic and aerobic exercise performance as well as physical stamina and reduces fatigue. These effects seem to be related to the antioxidant, anti-inflammatory, and metabolic activity of all its macronutrients, while each component of Chlorella contributes its bioactivity via a specific action. Chlorella is an excellent dietary source of high-quality protein in the context of physical exercise, as dietary proteins increase satiety, activation of the anabolic mTOR (mammalian Target of Rapamycin) pathway in skeletal muscle, and the thermic effects of meals. Chlorella proteins also increase intramuscular free amino acid levels and enhance the ability of the muscles to utilize them during exercise. Fiber from Chlorella increases the diversity of the gut microbiota, which helps control body weight and maintain intestinal barrier integrity, and the production of short-chain fatty acids (SCFAs), which improve physical performance. Polyunsaturated fatty acids (PUFAs) from Chlorella contribute to endothelial protection and modulate the fluidity and rigidity of cell membranes, which may improve performance. Ultimately, in contrast to several other nutritional sources, the use of Chlorella to provide high-quality protein, dietary fiber, and bioactive fatty acids may also significantly contribute to a sustainable world through the fixation of carbon dioxide and a reduction of the amount of land used to produce animal feed.

Biological active metabolites from microalgae for healthcare and pharmaceutical industries: A comprehensive review

Microalgae are photoautotrophic microorganisms which comprise of species from several phyla. Microalgae are promising in producing a varieties of products, including food, feed supplements, chemicals, and biofuels. Medicinal supplements derived from microalgae are of a significant market in which compounds such as -carotene, astaxanthin, polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and polysaccharides such as -glucan, are prominent. Microalgae species which are commonly applied for commercial productions include Isochrysis sp., Chaetoceros (Chlorella sp.), Arthrospira sp. (Spirulina Bioactive) and many more. In this present review, microalgae species which are feasible in metabolites production are being summarized. Metabolites produced by microalgae as well as their prospective applications in the healthcare and pharmaceutical industries, are comprehensively discussed. This evaluation is greatly assisting industrial stakeholders, investors, and researchers in making business decisions, investing in ventures, and moving the production of microalgae-based metabolites forward.

Skin Health Promoting Effects of Natural Polysaccharides and Their Potential Application in the Cosmetic Industry

Skincare is one of the most profitable product categories today. Consumers’ demand for skin-friendly products has stimulated the development of natural-ingredient-based cosmeceutical preparations over synthetic chemicals. Thus, natural polysaccharides have gained much attention since the promising potent efficacy in wound healing, moisturizing, antiaging, and whitening. The challenge is to raise awareness of polysaccharides with excellent bioactivities from natural sources and consequently incorporate them in novel and safer cosmetics. This review highlights the benefits of natural polysaccharides from plants, algae, and fungi on skin health, and points out some obstacles in the application of natural polysaccharides.

Chlorella unsaturated fatty acids suppress high-fat diet-induced obesity in C57/BL6J mice

Chlorella has been identified as a rich source of unsaturated fatty acids. Since the antiobesity effects of unsaturated fatty acids have been well documented; therefore, we explored the antiobesity actions of chlorella unsaturated fatty acids (C.UFAs) in the current study. The obtained results demonstrated C.UFAs, which contain abundant linoleic acid, could retard body weight gain (reducing body weigh by 13.93% after 16 weeks of treatment), improve blood glucose (19.29% lower) and lipid profile (23.45% lower in TG, 8.76% lower in TC) compared to high-fat diet-fed C57BL/6J mice. The possible underlying mechanisms might involve reducing hepatic lipid accumulation via down-regulation of lipogenic genes (PPARγ, C/EBPα, LPL, aP2, FAS, and SREBP-1c) and up-regulation of lipolytic gene (adiponectin). We also demonstrate C.UFAs could reduce HFD-induced adipocyte hypertrophy via activation of AMPK signaling pathway in adipose tissue and liver. In summary, our study highlights the potential of C.UFAs as a functional food for obesity management. PRACTICAL APPLICATION: Chlorella has already been commercialized as a functional food antiobesity function. In the current study, the unsaturated fatty acids isolated from chlorella were found to exert beneficial effects on hyperglycemia, hyperlipidemia, hepatic steatosis, and adipocyte hypertrophy in high-fat diet-fed mice. This may provide theoretical foundation for developing novel chlorella-based functional foods.

Microalgae-derived polysaccharides: Potential building blocks for biomedical applications

In recent years, the increasing concern about human health well-being has strongly boosted the search for natural alternatives that can be used in different fields, especially in biomedicine. This has put microalgae-based products in evidence since they contain many bioactive compounds, of which polysaccharides are attractive due to the diverse physicochemical properties and new or improved biological roles they play. Polysaccharides from microalgae, specially exopolysaccharides, are critically important for market purposes because they can be used as anti-inflammatory, immunomodulatory, anti-glycemic, antitumor, antioxidant, anticoagulant, antilipidemic, antiviral, antibacterial, and antifungal agents. Therefore, to obtain higher productivity and competitiveness of these naturally available compounds, the cultivation parameters and the extraction/purification processes must be better optimized in order to bring perspectives for the exploitation of products in commercial and clinical practice. In this sense, the objective of the present review is to elucidate the potential biomedical applications of microalgae-derived polysaccharides. A closer look is taken at the main polysaccharides produced by microalgae, methods of extraction, purification and structural determination, biological activities and their applications, and current status.

pH-Responsive Eco-Friendly Chitosan–Chlorella Hydrogel Beads for Water Retention and Controlled Release of Humic Acid

For improving the mechanical strength of controlled release fertilizer (CRF) hydrogels, a novel material of Chlorella was employed as a bio-based filler to prepare chitosan–chlorella hydrogel beads with physical crosslink method. Here, the synthesis mechanism was investigated, and the chitosan–chlorella hydrogel beads exhibited enhanced mechanical stability under centrifugation and sonication than pure chitosan hydrogel beads. Chlorella brought more abundant functional groups to original chitosan hydrogel, hence, chitosan–chlorella hydrogel beads represented greater sensitivity and controllable response to external factors including pH, salt solution, temperature. In distilled water, the hydrogel beads with 40 wt% Chlorella reached the largest water absorption ratio of 42.92 g/g. Moreover, the mechanism and kinetics process of swelling behavior of the chitosan–chlorella hydrogel beads were evaluated, and the loading and releasing of humic acid by the hydrogel beads as a carrier material were pH-dependent and adjustable, which exhibit the potential of chitosan–chlorella hydrogel beads in the field of controlled release carrier biomaterials.

Gastroprotective Effects of Ganoderma lucidum Polysaccharides with Different Molecular Weights on Ethanol-Induced Acute Gastric Injury in Rats

Ganoderma lucidum is known as a medicine food homology that can ameliorate gastrointestinal diseases. To evaluate the gastroprotective effects on different Ganoderma lucidum polysaccharides (GLPs), GLP was separated into three parts with different molecular weights using 100 kDa, 10 kDa, and 1 kDa membranes. The mitigation effects of different GLPs on ethanol-induced acute gastric injury were observed in rats. After pretreatment with different GLPs, especially GLP above 10 kDa, the symptoms of gastric mucosal congestion and bleeding were improved; serum myeloperoxidase, inflammatory factor, and histamine were decreased; and antioxidant activity and defense factors (NO and EGF) were increased. Results showed that GLP with different molecular weights had a dose-dependent effect in alleviating alcohol-induced gastric injury. The underlying mechanism might be related to regulating anti-oxidation, promoting the release of related defense factors, reducing inflammatory factors, and reducing the level of histamine in serum. The current work indicated that GLPs above 10 kDa could be applied as natural resources for producing new functional foods to prevent gastric injury induced by ethanol.

Characterization, antioxidant and anticoagulant properties of exopolysaccharide from marine microalgae

The sulfated exopolysaccharide extracted from marine microalgae attracted considerable attention from both the nutraceutical and pharmaceutical industries. In the present study biomass of five marine microalgae were screened to find strains with high capacity for the production of sulfated exopolysaccharides. The anticoagulant and antioxidant activities of extracted sulfated polysaccharides were evaluated using activated partial thromboplastin time (aPTT), prothrombin time (PT), DPPH and ABTS assays, respectively. The sulfated polysaccharides extracted from Picochlorum sp. showed a strong DPPH scavenging effect with 85% antioxidant activity. The sulfated polysaccharides of Chlorella sorokiniana, Chlorella sp. (L₂) and Chlorella sp. (D₁) scavenged more than 90% of the ABTS radicals. However, the sulfated polysaccharide extracted from Chlorella sorokiniana, and Chlorella sp. (N4) showed anticoagulant properties. The dual anticoagulant-antioxidant activities in Chlorella sorokiniana could be explained by the combination of various factors including sulfate content and their binding site, monosaccharide residue and glycoside bond which are involved in the polysaccharide’s bioactivity.

Sulfated exopolysaccharides (sPS) were extracted from marine green microalgae by the heated acid extraction method.

sPS with the higher sulfate/sugar ratio presented potent ABTS radical scavenging activity.

Some of the sPS revealed anticoagulant effects in activated partial thromboplastin time (aPTT) and prothrombin time (PT) assays.

Chlorella pyrenoidosa Polysaccharides as a Prebiotic to Modulate Gut Microbiota: Physicochemical Properties and Fermentation Characteristics In Vitro

This study was conducted to investigate the prebiotic potential of Chlorella pyrenoidosa polysaccharides to provide useful information for developing C. pyrenoidosa as a green healthy food. C. pyrenoidosa polysaccharides were prepared and their physicochemical characteristics were determined. The digestibility and fermentation characteristics of C. pyrenoidosa polysaccharides were evaluated using in vitro models. The results revealed that C. pyrenoidosa polysaccharides were composed of five non-starch polysaccharide fractions with monosaccharide compositions of Man, Rib, Rha, GlcA, Glc, Gal, Xyl and Ara. C. pyrenoidosa polysaccharides could not be degraded under saliva and the gastrointestinal conditions. However, the molecular weight and contents of residual carbohydrates and reducing sugars of C. pyrenoidosa polysaccharides were significantly reduced after fecal fermentation at a moderate speed. Notably, C. pyrenoidosa polysaccharides could remarkably modulate gut microbiota, including the promotion of beneficial bacteria, inhibition of growth of harmful bacteria, and reduction of the ratio of Firmicutes to Bacteroidetes. Intriguingly, C. pyrenoidosa polysaccharides can promote growth of Parabacteroides distasonis and increase short-chain fatty acid contents, thereby probably contributing to the promotion of intestinal health and prevention of diseases. Thus, these results suggested that C. pyrenoidosa polysaccharides had prebiotic functions with different fermentation characteristics compared with conventional prebiotics such as fructooligosaccharide, and they may be a new prebiotic for improving human health.

Structural characteristics and immunomodulatory effects of sulfated polysaccharides derived from marine algae

Marine algae are becoming an important source of valuable candidates of functional food that remain unexplored. Compositional analysis showed that marine algae contain essential nutrients, such as carbohydrates, proteins, fats, and minerals, of which polysaccharides are the main bioactive component. Depending on the source, marine algae polysaccharides are sulfated, which have diverse structures and compositions that influence their biological activities. A growing body of evidence has demonstrated that sulfated polysaccharides derived from marine algae (SPs) exhibit various bioactivities, especially immunomodulation. This review aims at summarizing the structural characteristics of SPs, their immunomodulatory effects, and the structural-immunomodulatory activity relationships between them from articles in recent decade, in order to provide a theoretical basis for the further applications of SPs as promising food or feed additives and possible health products to modulate the immune response.

Skincare application of medicinal plant polysaccharides - A review

Polysaccharides are macromolecules with important inherent properties and potential biotechnological applications. These complex carbohydrates exist throughout nature, especially in plants, from which they can be obtained with high yields. Different extraction and purification methods may affect the structure of polysaccharides and, due to the close relationship between structure and function, modify their biological activities. One of the possible applications of these polysaccharides is acting on the skin, which is the largest organ in the human body and can be aged by intrinsic and extrinsic processes. Skincare has been gaining worldwide attention not only to prevent diseases but also to promote rejuvenation in aesthetic treatments. In this review, we discussed the polysaccharides obtained from plants and their innovative potential for skin applications, for example as wound-healing, antimicrobial, antioxidant and anti-inflammatory, antitumoral, and anti-aging compounds.

Structure–immunomodulatory activity relationships of dietary polysaccharides

Polysaccharides are usually composed of more than ten monosaccharide units, which are connected by linear or branched glycosidic bonds. The immunomodulatory effect of natural polysaccharides is one of the most important bioactive function. In this review, molecular weight, monosaccharide (including galactose, mannose, rhamnogalacturonan-I arabinogalactan and uronic acid), functional groups (namely sulfate, selenium, and acetyl groups), types of glycoside bond connection (including β-1,3-D-glucosyl, α-1,4-D-glucosyl, β-1,4-D-glucosyl, α-1,6-D-glucosyl, β-1,4-D-mannosyl, and β-1,4-D-Xylopyranosyl), conformation and the branching degrees are systematically identified as their contribution to the immunostimulatory activity of polysaccharides. At present, studies on the structure-activity relationships of polysaccharides are limited due to their low purity and high heterogeneity. However, it is an important step in providing useful guidance for dietary supplements with polysaccharides. The chemical structures and the process of immune responses induced are necessary to be discussed. Polysaccharides may bind with the cell surface receptors to modulate immune responses. This review mainly discusses the structure-activity relationship of dietary polysaccharides.

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Structure - activity relationships of polysaccharides with immune-enhancing effect are proposed.

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Polysaccharides with the higher molecular weight are helpful to improve immunity.

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Higer galactose, mannose, rhamnogalacturonan-I, arabinogalacta,n and uronic acid contents have immunoregulation.

Extraction optimization, physicochemical characterization, and antioxidant activity of polysaccharides from Rhodosorus sp. SCSIO-45730

Microalgal polysaccharides have been reported in many studies due to their uniqueness, biocompatibility, and high value, and Rhodosorus sp. SCSIO-45730 was an excellent source of polysaccharides and β-glucans. However, the polysaccharides from the red unicellular alga Rhodosorus sp. SCSIO-45730 have barely been studied. In this work, hot water extraction of Rhodosorus sp. SCSIO-45730 polysaccharides (RSP) was optimized using response surface methodology (RSM) based on Box-Behnken design (BBD). The maximum RSP yield (9.29%) was achieved under the optimum extraction conditions: liquid-solid ratio of 50.00 mL g^-1; extraction temperature of 84 °C; extraction time of 2 h; and extraction times of 5 times. The results of physicochemical characterization showed that RSP had high sulfate and uronic acid with content of 19.58% and 11.57%, respectively, rough layered structure, and mainly contained glucose, galactose, xylose, and galacturonic acid with mass percentages of 34.08%, 28.70%, 12.46%, and 12.10%. Furthermore, four kinds of antioxidant assays were carried out, and the results indicated that RSP had strong scavenging activities on ABTS and hydroxyl radical and moderate scavenging activities on DPPH and ferrous chelating ability. These results indicated that RSP showed potential as a promising source of antioxidants applied in food, pharmaceutical, and cosmetics industry.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10811-021-02646-2.

Physicochemical properties, structural characterization and biological activities of polysaccharides from quinoa (Chenopodium quinoa Willd.) seeds

In this paper, membrane separation technology was employed to separate polysaccharide fractions from the water extract of quinoa seeds. The chemical composition, structure characteristic and morphology were analyzed by chemical methods and instrumental analysis including HPLC-DAD, UV, FT-IR, Congo red test, SEM, AFM, XRD, TGA and NMR. Results indicated that three polysaccharide fractions named as QPs-I, QPs-II and QPs-III were successfully separated using microfiltration and ultrafiltration membrane with MWCO of 300 and 10 kDa in sequence. The Mw and polysaccharide content of three fractions were QPs-I (4609 Da, 33.75%), QPs-II (15,932 Da, 45.31%) and QPs-III (960,895 Da, 34.65%), respectively. The polysaccharide in three fractions was heteropolysaccharide that mainly consisted of glucose, galactose and arabinose, with their combined monosaccharide percentage being 91.17% in QPs-I, 87.81% in QPs-II, and 91.72% in QPs-III, respectively. All three polysaccharide fractions contained triple-helix structure. Biological experiment showed that antioxidant and antidiabetic activities in dose-dependent manners and also revealed immunoregulatory activity on RAW264.7 cells. These results indicated that QPs has the potential to be used in a natural agent in antioxidant, antidiabetic and immunoregulation functional food.

Optimization of the composite enzyme extraction of polysaccharide from Erythronium sibiricum bulb and its immunoregulatory activities

An efficient compound enzyme extraction process was developed and optimized to extract the polysaccharide from Erythronium sibiricum bulb via response surface methodology. The polysaccharide E2P was obtained. Then, the preliminary characteristics of E2P were determined via colorimetry and chromatography. Additionally, the immunoregulatory activities of E2P and another polysaccharide (ESBP, extracted using the hot water method) were compared. The optimized extraction results were as follows: temperature (54.56 °C), time (2.52 h), pH (6.53), and enzyme concentration ratio (0.5% cellulase:1.5% amylase). The yield (64.18% ± 2.91%) obtained under the aforementioned conditions was considerably higher than the yield of ESBP (37.25% ± 0.17%). The total sugar, uronic acid, starch, and protein contents of E2P were 81.77% ± 2.84%, 3.31% ± 0.45%, 3.29% ± 0.01%, and 0.24% ± 0.02%, respectively. The HPLC result suggested that the predominant monosaccharides of E2P included glucose, galactose, and arabinose, with a molar ratio of 543.2:1:1.8. The in vitro tests in RAW264.7 cells indicated that ESBP exhibited better immunomodulatory activities than E2P. In particular, ESBP can promote the proliferation, phagocytosis, and cytokine secretion abilities of cytokines, such as nitric oxide, tumor necrosis factor-α, and interleukin (IL)-1β of RAW264.6 cells. By contrast, E2P can only promote phagocytosis ability and the secretion of IL-1β.

Characteristics and antifatigue activity of graded polysaccharides from Ganoderma lucidum separated by cascade membrane technology

In this paper, cascade membrane technology was utilized to classify polysaccharides from Ganoderma lucidum (GLPs). The properties and antifatigue activity of graded polysaccharides were identified and compared. GLPs were separated using cascade ultrafiltration membranes of 100 kDa, 10 kDa and 1 kDa in sequence. The molecular weights of polysaccharides in these GLP fractions were approximately 322.0 kDa, 18.8 kDa and 6.4 kDa, and all polysaccharides were in active β-configurations. This showed that all graded GLPs could elongate swimming time, improve endurance and promote fatigue recovery, especially polysaccharides with molecular weights above 10 kDa. This demonstrated that GLPs could decrease the activities of SUN and CK and the levels of MDA and BLA. They also increased the level of Gly, accelerated fat transformation, and improved the activities of GPx, SOD and LDH in all treated mice. Accordingly, GLPs above 10 kDa might be potential agents with antifatigue activity.

A critical review on production of biopolymers from algae biomass and their applications

Algae is abundantly present in our ecosystems and can be easily extracted and used for production of biopolymers. Algae does not produce any anthropogenic, harmful effects, has a good growth rate, and cultivable in wastewater. This literature elucidates the potential of algae biomass by comparing various seaweed and microalgae strains. The routes for biopolymer production were portrayed and their novel methods of isolation such as microwave assisted, ultrasound assisted, and subcritical water assisted extraction are discussed in detail. These novel methods are observed to be highly efficient compared to conventional solvent extraction, with the microwave assisted and ultrasound assisted processes yielding 33% and 5% more biopolymer respectively than the conventional method. Biopolymers are used in variety of applications such as environmental remediation, adsorbent and antioxidant. Biopolymer is shown to be highly effective in the removal of potentially toxic elements and is seen to extract more than 40 mg PTE/g biopolymer.

Strain-Specific Biostimulant Effects of Chlorella and Chlamydomonas Green Microalgae on Medicago truncatula

Microalgae have been identified to produce a plethora of bioactive compounds exerting growth stimulating effects on plants. The objective of this study was to investigate the plant-growth-promoting effects of three selected strains of eukaryotic green microalgae. The biostimulatory effects of two Chlorella species (MACC-360 and MACC-38) and a Chlamydomonas reinhardtii strain (cc124) were investigated in a Medicago truncatula model plant grown under controlled greenhouse conditions. The physiological responses of the M. truncatula A17 ecotype to algal biomass addition were characterized thoroughly. The plants were cultivated in pots containing a mixture of vermiculite and soil (1:3) layered with clay at the bottom. The application of live algae cells using the soil drench method significantly increased the plants’ shoot length, leaf size, fresh weight, number of flowers and pigment content. For most of the parameters analyzed, the effects of treatment proved to be specific for the applied algae strains. Overall, Chlorella application led to more robust plants with increased fresh biomass, bigger leaves and more flowers/pods compared to the control and Chlamydomonas-treated samples receiving identical total nutrients.

Polysaccharides-based bio-nanostructures and their potential food applications

Polysaccharides are omnipresent biomolecules that hold great potential as promising biomaterials for a myriad of applications in various biotechnological and industrial sectors. The presence of diverse functional groups renders them tailorable functionalities for preparing a multitude of novel bio-nanostructures. Further, they are biocompatible and biodegradable, hence, considered as environmentally friendly biopolymers. Application of nanotechnology in food science has shown many advantages in improving food quality and enhancing its shelf life. Recently, considerable efforts have been made to develop polysaccharide-based nanostructures for possible food applications. Therefore, it is of immense importance to explore literature on polysaccharide-based nanostructures delineating their food application potentialities. Herein, we reviewed the developments in polysaccharide-based bio-nanostructures and highlighted their potential applications in food preservation and bioactive "smart" food packaging. We categorized these bio-nanostructures into polysaccharide-based nanoparticles, nanocapsules, nanocomposites, dendrimeric nanostructures, and metallo-polysaccharide hybrids. This review demonstrates that the polysaccharides are emerging biopolymers, gaining much attention as robust biomaterials with excellent tuneable properties.