Low molecular weight fucoidan alleviates cerebrovascular damage by promoting angiogenesis in type 2 diabetes mice

Preparation and bioactivities of low-molecular weight fucoidans and fuco-oligosaccharides: A review

Fucoidans are a kind of naturally sulfated polysaccharides that are primarily derived from brown algae and marine invertebrates. They are mainly composed of L-fucose and sulphate group. In the past decades, fucoidans have been attracted much attention for its wide range of pharmacological activities. However, fucoidans are difficult to be absorbed due to their high molecular weight. Notably, low-molecular weight fucoidan (LMWF) and fuco-oligosaccharide are more readily absorbed and have equal or superior biological activities. Therefore, degradation of fucoidan has become a research hot spot in recent years. Presently, methods for fucoidan degradation primary include enzymatic degradation, chemical degradation, and physical degradation. Enzymatic degradation has advantages of mild hydrolysis conditions, good selectivity and few by-products. Chemical degradation is characterized by simple operation, low cost, and easy for industrial applications. This review article summarizes research progress on fucoidan-degrading enzymes, preparation of LMWF and fuco-oligosaccharides by enzymatic degradation, physical degradation, and chemical degradation, and biological activities of these products. This article provides information useful for chemists that are interested in preparation of LMWF and fuco-oligosaccharides, for pharmacologists that are devoted to develop fucoidan-derived bioactive molecules, and for manufacturers of fucoidan-derived products, thus promoting transformation of these products in food and pharmaceutical areas.

A comprehensive review of preparation and pharmacology of low molecular weight fucoidan

Fucoidan is a type of sulfated fucans originated from many marine animals and algae, its unique molecular characteristics rich in L-fucose and sulfate ester group give it a wide range of biological properties. The natural polysaccharide has been used as a clinical drug for kidney disease for many years. However, high molecular weight associated defects, low water solubility and high viscosity, reduce its bioavailability. Consequently, low molecular weight fucoidan (LMWF) with better physicochemical properties originally has been widely studied its biological properties and once regarded as a substitute of heparin for its anticoagulant activity. Presently, large number of researches reported its various bioactivities, including anti-coagulation, anti-oxidation, anti-inflammation, anti-tumor, etc., but the LMWFs prepared by different methods from various species possess distinct molecular characteristics, which results in discrepant biological activities and the underlying mechanisms. Based on the research progress of LMWF, this review article comprehensively overviewed the preparation methods, toxicity, and pharmacology, which highlights LMWF as a valuable marine active substance for developing marine functional foods and drugs.

From seaweed to superfood: Next-generation fucoidan extraction, structural and bioactivity evaluation for sustainable health solutions

Sulfated fucoidan was extracted from Sargassum sp. using hydrothermal (HT), microwave-assisted extraction (MAE), and ultrasonic-assisted extraction (UAE) methods, each with distinct environmental and bioactivity profiles. Hydrothermal extraction yielded the highest amount of fucoidan (105.64 ± 2.14 mg/g) at 140 °C for 40 min. The extraction methods significantly influenced fucoidan's physicochemical composition and bioactivity, with antioxidant potential in the order MAE > UAE > HT. Notably, the hydrothermal extract (140-40-Pure) exhibited the strongest α-glucosidase inhibition (96 %, IC50 346.32 μg/mL) via mixed-type inhibition, while MAE and UAE extracts demonstrated superior prebiotic activity, supporting Lactobacillus plantarum and L. kefiri growth in vitro. Despite yielding lower quantities, UAE extracts showed consistent bioactivity and superior structural composition. Environmentally, UAE stands out as the greenest extraction method, with lower CO₂ emissions, reduced energy and solvent usage, and minimized processing time, aligning with SDGs-3. This research highlights the UAE's potential for scalable, eco-friendly production of bioactive fucoidans with diverse applications in the nutraceutical and pharmaceutical industries.

Effects of a mitochondrial calcium uniporter and P-selectin inhibitors on neural injury induced by global cerebral ischemia-reperfusion in male rats

Neural injury following ischemia-reperfusion (I/R) is induced by multiple pathophysiological pathways. This study aimed to use mitochondrial calcium channel and p-selectin inhibitors to weaken these pathways. One hundred and two rats were randomly divided into six groups. In the sham group, cerebral I/R induction and drug intervention were not performed. In the I/R group, cerebral I/R induction was induced. In the RR + FCN group, animals received only ruthenium red (RR) and fucoidan (FCN) intraperitoneally without I/R induction. In the I/R + RR group, animals received RR during the cerebral I/R period. In the I/R + FCN group, FCN was administered along with cerebral I/R. In the I/R +(RR + FCN) group, animals exposed to cerebral I/R received a combination of RR and FCN simultaneously. The shuttle box and new object tests were used to assess learning and memory. The superoxide dismutase (SOD), malondialdehyde (MDA), interleukin-1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α) levels in the hippocampus were measured. Neuronal death in the hippocampal CA1 area was assessed via hematoxylin-eosin staining. FCN and RR significantly decreased the tissue MDA, IL-1β, TNF-α levels while increased the SOD level. These inhibitors significantly reduced learning disorders and cerebral edema following I/R. The rate of neuronal death was significantly lower in each of the receiving RR and FCN groups. This study revealed that the use of FCN and RR significantly attenuated the pathways associated with oxidative stress and inflammation as well as neuronal death following cerebral I/R, thereby reducing learning and memory impairments. The effects of neuroprotection were further determined when two inhibitors were used simultaneously. HIGHLIGHTS: Cerebral ischemia-reperfusion is associated with many neurological, sensory and motor defects. Multiple pathways of neural pathophysiology are activated during cerebral ischemia-reperfusion. The Administration of ruthenium and fucoidan weakens inflammatory pathways, oxidative stress, and learning dysfunctions caused by cerebral ischemia and reperfusion. Stronger Neuroprotective effects were observed during the simultaneous administration of ruthenium and fucoidan.

Recent Advances of the Zebrafish Model in the Discovery of Marine Bioactive Molecules

Marine natural products are increasingly utilized in nutrition, cosmetics, and medicine, garnering significant attention from researchers globally. With the expansion of marine resource exploration in recent years, the demand for marine natural products has risen, necessitating rapid and cost-effective activity evaluations using model organisms. Zebrafish, a valuable vertebrate model, has become an efficient tool for screening and identifying safe, active molecules from marine natural products. This review, based on nearly 10 years of literature, summarizes the current status and progress of zebrafish models in evaluating marine natural product bioactivity. It also highlights their potential in exploring marine resources with health benefits, offering a reference for the future development and utilization of marine biological resources.

Therapeutic potential of fucoidan in central nervous system disorders: A systematic review

Central nervous system (CNS) disorders have a complicated pathogenesis, and to date, no single mechanism can fully explain them. Most drugs used for CNS disorders primarily aim to manage symptoms and delay disease progression, and none have demonstrated any pathological reversal. Fucoidan is a safe, sulfated polysaccharide from seaweed that exhibits multiple pharmacological effects, and it is anticipated to be a novel treatment for CNS disorders. To assess the possible clinical uses of fucoidan, this review aims to provide an overview of its neuroprotective mechanism in both in vivo and in vitro CNS disease models, as well as its pharmacokinetics and safety. We included 39 articles on the pharmacology of fucoidan in CNS disorders. In vitro and in vivo experiments demonstrate that fucoidan has important roles in regulating lipid metabolism, enhancing the cholinergic system, maintaining the functional integrity of the blood-brain barrier and mitochondria, inhibiting inflammation, and attenuating oxidative stress and apoptosis, highlighting its potential for CNS disease treatment. Fucoidan has a protective effect against CNS disorders. With ongoing research on fucoidan, it is expected that a natural, highly effective, less toxic, and highly potent fucoidan-based drug or nutritional supplement targeting CNS diseases will be developed.

Fucoidan prevents diabetic cognitive dysfunction via promoting TET2-mediated active DNA demethylation in high-fat diet induced diabetic mice

Diabetic cognitive dysfunction (DCD) refers to cognitive impairment in individuals with diabetes, which is one of the most important comorbidities and complications. Preliminary evidence suggests that consuming sufficient dietary fiber could have benefits for both diabetes and cognitive function. However, the effect and underlying mechanism of dietary fiber on DCD remain unclear. We conducted a cross-sectional analysis using data from NHANES involving 2072 diabetics and indicated a significant positive dose-response relationship between the dietary fiber intake and cognitive performance in diabetics. Furthermore, we observed disrupted cognitive function and neuronal morphology in high-fat diet induced DCD mice, both of which were effectively restored by fucoidan supplementation through alleviating DNA epigenetic metabolic disorders. Moreover, fucoidan supplementation enhanced the levels of short-chain fatty acids (SCFAs) in the cecum of diabetic mice. These SCFAs enhanced TET2 protein stability by activating phosphorylated AMPK and improved TETs activity by reducing the ratio of (succinic acid + fumaric acid)/ α-ketoglutaric acid, subsequently enhancing TET2 function. The positive correlation between dietary fiber intake and cognitive function in diabetics was supported by human and animal studies alike. Importantly, fucoidan can prevent the occurrence of DCD by promoting TET2-mediated active DNA demethylation in the cerebral cortex of diabetic mice.

In Vivo Tissue Distribution and Pharmacokinetics of FITC-Labelled Hizikia fusiforme Polyphenol-Polysaccharide Complex in Mice

In this study, a quantitative method based on fluorescein isothiocyanate (FITC)-labelled Hizikia fusiforme polyphenol-polysaccharide complex (HPC) and its purified fractions (PC1, PC4) was used, and its pharmacokinetics and tissue distribution were investigated in mice. The results showed that the FITC-labelled method had good linearity (R2 > 0.99), intra-day and inter-day precision (RSD, %) consistently lower than 15%, recovery (93.19-106.54%), and stability (RSD < 15%), which met the basic criteria for pharmacokinetic studies. The pharmacokinetic and tissue distribution results in mice after administration showed that all three sample groups could enter the blood circulation. and HPC-FITC had a longer half-life (T1/2: 26.92 ± 0.76 h) and mean retention time (MRT0-∞: 36.48 h) due to its larger molecular weight. The three groups of samples could be absorbed by the organism in a short time (0.5 h) mainly in the stomach and intestine; the samples could be detected in the urine after 2 h of administration indicating strong renal uptake, and faecal excretion reached its maximum at 12 h. The samples were also detected in the urine after 2 h of administration. This study provides some theoretical basis for the tissue distribution pattern of polyphenol-polysaccharide complex.

Low molecular weight fucoidan restores diabetic endothelial glycocalyx by targeting neuraminidase2: A new therapy target in glycocalyx shedding

BACKGROUND AND PURPOSE

Diabetic vascular complication is a leading cause of disability and mortality in diabetes patients. Low molecular weight fucoidan (LMWF) is a promising drug candidate for vascular complications. Glycocalyx injury predates the occurrence of diabetes vascular complications. Protecting glycocalyx from degradation relieves diabetic vascular complications. LMWF has the potential to protect the diabetes endothelial glycocalyx from shedding.

EXPERIMENTAL APPROACH

The protective effect of LMWF on diabetic glycocalyx damage was investigated in db/db mice and Human Umbilical Vein Endothelial Cells (HUVEC) through transmission electron microscopy and WGA labelling. The effect of LMWF on glycocalyx degrading enzymes expression was investigated. Neuraminidase2 (NEU2) overexpression/knockdown was performed in HUVECs to verify the important role of NEU2 in glycocalyx homeostasis. The interaction between NEU2 and LMWF was detected by ELISA and surface plasmon resonance analysis (SPR).

KEY RESULTS

LMWF normalizes blood indexes including insulin, triglyceride, uric acid and reduces diabetes complications adverse events. LMWF alleviates diabetic endothelial glycocalyx damage in db/db mice kidney/aorta and high concentration glucose treated HUVECs. NEU2 is up-regulated in db/db mice and HUVECs with high concentration glucose. Overexpression/knockdown NEU2 results in glycocalyx shedding in HUVEC. Down-regulation and interaction of LMWF with NEU2 is a new therapy target in glycocalyx homeostasis. NEU2 was positively correlated with phosphorylated IR-β.

CONCLUSION AND IMPLICATIONS

NEU2 is an effective target for glycocalyx homeostasis and LMWF is a promising drug to alleviate vascular complications in diabetes by protecting endothelial glycocalyx.

Intestinal Absorption of Nanoparticles to Reduce Oxidative Stress and Vasoconstriction for Treating Diabetic Nephropathy

The etiology of diabetic nephropathy (DN) is complex, and the incidence is increasing year by year. The patient's kidney showed oxidative stress damage, increasing active oxygen species (ROS) content, and vasoconstriction. Due to poor drug solubility and low renal accumulation, the current treatment regimens have not effectively alleviated glomerulopathy and other kidney damage caused by DN. Therefore, it is of great significance to explore new treatment strategies and drug delivery systems. Here, we constructed an oral nanodelivery system (Tel/CAN@CS-DA) that reduced oxidative stress and vasoconstriction. Deoxycholic acid (DA)-modified nanoparticles entered into intestinal epithelial cells (Caco2 cells) via the bile acid biomimetic pathway, then escaped from the lysosomes and eventually spat out the cells, increasing the oral absorption of nanoparticles. Chitosan (CS) nanoparticles could achieve renal targeting through specific binding with a renal giant protein receptor and deliver drugs to renal tubule epithelial cells (HK-2 cells). In vitro studies also proved that telmisartan (Tel) and canagliflozin (CAN) effectively removed cellular reactive oxygen species (ROS) and reduced HK-2 cell apoptosis caused by high glucose. In the in vivo model induced by streptozotocin (STZ), the results showed that the nanosystem not only elevated AMPK protein expression, inhibited angiotensin II (Ang II) protein expression to effectively reduce oxidative stress level, dilated renal blood vessels but also reduced the degree of inflammation and fibrosis. Overall, Tel/CAN@CS-DA multifunctional oral nanosystem can effectively treat DN with low toxicity, which provides a new idea for the treatment of DN.

Laminaria japonica polysaccharide alleviates type 2 diabetes by regulating the microbiota-gut-liver axis: A multi-omics mechanistic analysis

The hypoglycemic effects of low-molecular-weight Laminaria japonica polysaccharide (LJO) were investigated in type 2 diabetes mellitus (T2DM) mice, focusing on its effect on the microbiome, metabolome, and transcriptome. The findings demonstrated that LJO significantly reduced fasting blood glucose levels, insulin levels, and inflammatory factors. Additionally, LJO induced changes in gut microbiota composition and increased the concentrations of cecal short-chain fatty acids. Analysis of transcriptomics and metabolomics data revealed that LJO primarily altered the endocrine and digestive systems, signal transduction, and lipid metabolism. It led to a decrease in palmitic acid levels and an increase in glutathione levels. Real-time quantitative polymerase chain reaction assay suggested that LJO upregulated Irs1 expression, consequently reducing insulin resistance. These findings strongly suggest that LJO holds promise in ameliorating T2DM and may serve as a potential dietary supplement for patients with T2DM.

Polysaccharides from the Sargassum and Brown Algae Genus: Extraction, Purification, and Their Potential Therapeutic Applications

Brown macroalgae represent one of the most proliferative groups of living organisms in aquatic environments. Due to their abundance, they often cause problems in aquatic and terrestrial ecosystems, resulting in health problems in humans and the death of various aquatic species. To resolve this, the application of Sargassum has been sought in different research areas, such as food, pharmaceuticals, and cosmetics, since Sargassum is an easy target for study and simple to obtain. In addition, its high content of biocompounds, such as polysaccharides, phenols, and amino acids, among others, has attracted attention. One of the valuable components of brown macroalgae is their polysaccharides, which present interesting bioactivities, such as antiviral, antimicrobial, and antitumoral, among others. There is a wide variety of methods of extraction currently used to obtain these polysaccharides, such as supercritical fluid extraction (SFE), pressurized liquid extraction (PLE), subcritical water extraction (SCWE), ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), and microwave-assisted extraction (MAE). Therefore, this work covers the most current information on the methods of extraction, as well as the purification used to obtain a polysaccharide from Sargassum that is able to be utilized as alginates, fucoidans, and laminarins. In addition, a compilation of bioactivities involving brown algae polysaccharides in in vivo and in vitro studies is also presented, along with challenges in the research and marketing of Sargassum-based products that are commercially available.

The Anti-Inflammatory Effect of Low Molecular Weight Fucoidan from Sargassum siliquastrum in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages via Inhibiting NF-κB/MAPK Signaling Pathways

Brown seaweed is a rich source of fucoidan, which exhibits a variety of biological activities. The present study discloses the protective effect of low molecular weight fucoidan (FSSQ) isolated from an edible brown alga, Sargassum siliquastrum, on lipopolysaccharide (LPS)-stimulated inflammatory responses in RAW 264.7 macrophages. The findings of the study revealed that FSSQ increases cell viability while decreasing intracellular reactive oxygen species production in LPS-stimulated RAW 264.7 macrophages dose-dependently. FSSQ reduced the iNOS and COX-2 expression, inhibiting the NO and prostaglandin E2 production. Furthermore, mRNA expression of IL-1β, IL-6, and TNF-α was downregulated by FSSQ via modulating MAPK and NF-κB signaling. The NLRP3 inflammasome protein complex, including NLRP3, ASC, and caspase-1, as well as the subsequent release of pro-inflammatory cytokines, such as IL-1β and IL-18, release in LPS-stimulated RAW 264.7 macrophages was inhibited by FSSQ. The cytoprotective effect of FSSQ is indicated via Nrf2/HO-1 signaling activation, which is considerably reduced upon suppression of HO-1 activity by ZnPP. Collectively, the study revealed the therapeutic potential of FSSQ against inflammatory responses in LPS-stimulated RAW 264.7 macrophages. Moreover, the study suggests further investigations on commercially viable methods for fucoidan isolation.

Preparation and Properties of Asymmetric Polyvinyl Pyrroli-Done/Polycaprolactone Composite Nanofiber Loaded with Tea Tree Extract

To develop a novel asymmetric nanofiber membrane with antioxidant and antibacterial activities, biocompatible polyvinyl pyrrolidone (PVP) and polycaprolactone (PCL) were used as carriers to load water-soluble tea tree extract (TTE) and hydrophobic tea tree oil (TTO) via electrospinning and electrostatic spraying, respectively, which was named as TTE-PVP-3/TTO-PCL. The results show that uniform TTE-PVP nanofibers with an average diameter of 95 ± 27 nm could be obtained when the mass ratio of TTE to PVP was set as 1:3. Homogeneous TTO/PCL microspheres with an average size of 4.38 ± 0.79 µm could be obtained when the propulsion speed was 0.08 mm/min and the voltage was 10 KV. The activity study showed that TTE could only improve the antioxidant activity of TTE-PVP-3/TTO-PCL, while TTO could improve the antibacterial activity effectively. Under experimental conditions, the inhibition zones of TTE-PVP-3/TTO-PCL against Staphylococcus aureus and Escherichia coli were 7.50 ± 0.48 mm and 9.55 ± 0.45 mm, respectively, and its scavenging rates for 2,2-diphenylpicrylhydrazyl (DHPP) and hydroxyl radical were 59.79 ± 4.10% and 61.02 ± 4.95%, respectively. In conclusions, TTE-PVP-3/TTO PCL can be potentially used as a new kind of anti-oxidative and antibacterial wound dressings.