Immunostimulatory Effect of Sulfated Galactans from the Green Seaweed Caulerpa cupressoides var. flabellata

A critical review on pharmacological properties of sulfated polysaccharides from marine macroalgae

The marine ecosystem contains an assorted range of organisms, among which macroalgae stands out marine resources as an invaluable reservoir of structurally diverse bioactive compounds. Marine macroalgae are considered as primary consumers have gained more attention for their bioactive components. Sulfated polysaccharides (SPs) are complex polymers found in macroalgae that play a crucial role in their cell wall composition. This review consolidates high-tech methodologies employed in the extraction of macroalgal SPs, offering a valuable resource for researchers focuses in the pharmacological relevance of marine macromolecules. The pharmacological activities of SPs, focusing on their therapeutic action by encompassing diverse study models are summarized. Furthermore, in silico docking studies facilitates a comprehensive understanding of SPs interactions with their binding sites providing a valuable insight for future endeavors. The biological properties of algal SPs, along with a brief reference to mode of action based on different targets are presented. This review utilizes up-to-date research discoveries across various study models to elucidate the biological functions of SPs, focusing on their molecular-level mechanisms and offering insights for prospective investigations. Besides, the significance of SPs from seaweeds is highlighted, showcasing their potential beneficial applications in promoting human health. With promising biomedical prospects, this review explores the extensive uses and experimental evidence supporting the important roles of SPs in various fields.

Immunomodulatory Activity and Its Mechanisms of Two Polysaccharides from Poria cocos

Polyporaceae is an important fungal family that has been a source of natural products with a range of pharmaceutical activities in China. In our previous study, two polysaccharides, PCWPW and PCWPS, with significant antioxidant and antidepressant activity were obtained from Poria cocos. In this study, we evaluated their potential molecular mechanisms in the immunomodulation of macrophages. PCWPW and PCWPS were characterized by GC-MS analysis to contain 1,3-linked Glcp. ELISA assays results demonstrated that the secretion of TNF-α was significantly enhanced by PCWPW/PCWPS. RNA-seq data demonstrated that PCWPS treatment modulated the expression of immune-related genes in macrophages, which was further confirmed by RT-qPCR assays. The activation of TNF-α secretion was found to be mannose receptor (MR) dependent and suppressed by MR inhibitor pretreatment. Moreover, the amount of TNF-α cytokine secretion in PCWPW/PCWPS-induced RAW264.7 cells was decreased when pretreated with NF-κB or MAPK signaling pathway inhibitors. Collectively, our results suggested that PCWPW and PCWPS possessed immunomodulatory activity that regulates TNF-α expression through the NF-κB/MAPK signaling pathway by binding to mannose receptors. Therefore, PCWPW and PCWPS isolated from Poria cocos have potential as drug candidates for immune-related disease treatment.

Sulfated Polysaccharides from Macroalgae-A Simple Roadmap for Chemical Characterization

The marine environment presents itself as a treasure chest, full of a vast diversity of organisms yet to be explored. Among these organisms, macroalgae stand out as a major source of natural products due to their nature as primary producers and relevance in the sustainability of marine ecosystems. Sulfated polysaccharides (SPs) are a group of polymers biosynthesized by macroalgae, making up part of their cell wall composition. Such compounds are characterized by the presence of sulfate groups and a great structural diversity among the different classes of macroalgae, providing interesting biotechnological and therapeutical applications. However, due to the high complexity of these macromolecules, their chemical characterization is a huge challenge, driving the use of complementary physicochemical techniques to achieve an accurate structural elucidation. This review compiles the reports (2016-2021) of state-of-the-art methodologies used in the chemical characterization of macroalgae SPs aiming to provide, in a simple way, a key tool for researchers focused on the structural elucidation of these important marine macromolecules.

Recent Discoveries on Marine Organism Immunomodulatory Activities

Marine organisms have been shown to be a valuable source for biologically active compounds for the prevention and treatment of cancer, inflammation, immune system diseases, and other pathologies. The advantage of studying organisms collected in the marine environment lies in their great biodiversity and in the variety of chemical structures of marine natural products. Various studies have focused on marine organism compounds with potential pharmaceutical applications, for instance, as immunomodulators, to treat cancer and immune-mediated diseases. Modulation of the immune system is defined as any change in the immune response that can result in the induction, expression, amplification, or inhibition of any phase of the immune response. Studies very often focus on the effects of marine-derived compounds on macrophages, as well as lymphocytes, by analyzing the release of mediators (cytokines) by using the immunological assay enzyme-linked immunosorbent assay (ELISA), Western blot, immunofluorescence, and real-time PCR. The main sources are fungi, bacteria, microalgae, macroalgae, sponges, mollusks, corals, and fishes. This review is focused on the marine-derived molecules discovered in the last three years as potential immunomodulatory drugs.

A new polysaccharide from Caulerpa chemnitzia induces molecular shifts of immunomodulation on macrophages RAW264.7

•

CCP showed significant immunomodulatory effects.

•

CCP raising the level of NO, TNF-α, and IL-6 of macrophages RAW264.7.

•

Investigation on the metabolites and genes changes in CCP-induced RAW264.7.

•

Potential immunostimulatory mechanism of CCP on RAW264.7 was elucidated.

Investigation on Caulerpa chemnitzia polysaccharides led to the finding of a new polysaccharide (CCP). The basic components of CCP were the total sugar (59.18% ± 0.57%), the uronic acids (36.75% ± 0.28%) and the sulfate (42.50% ± 0.42%), in total content. The physicochemical analysis revealed that CCP was a heteropolysaccharide with a molecular weight of 321.6 KDa, and composed of arabinose, fucose, glucose, mannose, galactose, xylose, fructose, ribose, glucuronic acid and galacturonic acid. The immunomodulatory assay showed that CCP played an important role in activating cell viability, the nitric oxide product and cytokines (IL-6 and TNF-α) secretion. Furthermore, the transcript-metabolic analysis displayed a total of 7692 differentially expressed genes (DEGs) and 95 differentially accumulated metabolites (DAMs), and revealed that CCP may play an immunomodulatory effect by activating NF-κB signaling pathway and arachidonic acid metabolism pathway. These findings will provide a basic understanding to further investigation of Caulerpa polysaccharides.

Characterization and immunomodulatory activity of sulfated galactan from the red seaweed Gracilaria fisheri

Polysaccharides from the red seaweed Gracilaria fisheri possess many functions, which include antioxidant, antiviral, and antibacterial activities. However, detailed data on their immunomodulatory activities are scarce. Here, we isolated sulfated galactans (SG) from G. fisheri. We found that the predominant SG from G. fisheri, termed SG-1, had an estimated molecular mass of 100 kDa and activated murine J774A.1 macrophages via the dectin-1 signaling pathway. Furthermore, we observed enhancement of nitric oxide (NO) secretion, increased expression of inducible nitric oxide synthase (iNOS) mRNA, and increased mRNA levels of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukins IL-1β and IL-6 by SG-1 in macrophages. Moreover, there was higher expression of intercellular adhesion molecule 1 (ICAM-1) and co-stimulatory molecules (B7-1 and B7-2) mRNA. Treatment with G. fisheri SG-1 at 50 μg/mL generally achieved or exceeded the pro-inflammatory activities of 100 ng/mL lipopolysaccharide. Our study demonstrates immune-stimulatory activities of G. fisheri SG that may be of value for immune-potentiating treatment in humans or livestock.