Modulation Effects of Sargassum pallidum Extract on Hyperglycemia and Hyperlipidemia in Type 2 Diabetic Mice

The aim of this study was to investigate the antidiabetic effect of the extract from Sargassum pallidum (SPPE) on type 2 diabetes mellitus (T2DM) mice. SPPE treatment alleviated hyperglycemia, insulin resistance (IR), liver and pancreatic tissue damage, hyperlipidemia and hepatic oxidative stress resulting from T2DM. SPPE reversed phosphoenolpyruvate carboxylase (PEPCK) and hexokinase (HK) activities to improve gluconeogenesis and glycogen storage in the liver. Furthermore, SPPE modulated glucose metabolism by regulating the levels of mRNA expression involving the PI3K/Akt/FOXO1/G6pase/GLUT2 pathway and could inhibit fatty acid synthesis by reducing the gene expression levels of fatty acid synthase (FAS) and acetyl-CoA carboxylase-1 (ACC-1). A 16 sRNA analysis indicated that SPPE treatment also reversed gut dysbiosis by increasing the abundance of beneficial bacteria (Bacteroides and Lactobacillus) and suppressing the proliferation of harmful bacteria (Enterococcus and Helicobacter). Untargeted metabolomics results indicated that histidine metabolism, nicotinate and nicotinamide metabolism and fatty acid biosynthesis were significantly influenced by SPPE. Thus, SPPE may be applied as an effective dietary supplement or drug in the management of T2DM.

Fucoidan derived from Sargassum pallidum alleviates metabolism disorders associated with improvement of cardiac injury and oxidative stress in diabetic mice

Type 2 diabetes mellitus (T2DM) and its complications have become a serious global health epidemic. Cardiovascular complications have considered as a major cause of high mortality in diabetic patients. Fucoidans from brown algae have diverse medicinal activities, however, few studies reported pharmacological activity of Sargassum. pallidum fucoidan (Sp-Fuc). Therefore, the aim of this study was to investigate the effects of Sp-Fuc on diabetic symptoms and cardiac injury in spontaneous diabetic db/db mice. SP-Fuc at 200 mg/(kg/d) was administered intragastrically to db/db mice for 8 weeks, the effects on hyperlipidemia, hyperglycemia, insulin resistance, and cardiac damage, as well as oxidative stress, inflammation, Nrf2/ARE, and NF-κB signaling pathways, were investigated. Our data demonstrated that Sp-Fuc significantly (p < 0.05) decreased body weights, hyperlipidemia, and hyperglycemia in db/db mice, along with improved insulin sensitivity. Additionally, Sp-Fuc significantly (p < 0.05) alleviated cardiac dysfunction and pathological morphology of cardiac tissue. Sp-Fuc also significantly (p < 0.05) decreased lipid peroxidation, increased antioxidant function, as well as reduced cardiac inflammation, possibly through Nrf2/ARE and NF-κB signaling. Sp-Fuc can ameliorate the metabolism disorders of glucose and lipid in diabetic mice by activating Nrf2/ARE antioxidant signaling, simultaneously reducing cardiac redox imbalance and inflammatory damage. The present findings provide a perspective on the therapy strategy for T2DM and its complications.

Preparation and characterization of Sargassum pallidum polysaccharide nanoparticles with enhanced antioxidant activity and adsorption capacity

Sargassum pallidum polysaccharide nanoparticle (nSPP-30) was prepared via antisolvent precipitation method and the preparation conditions were optimized. The effects of nanocrystallization on the structure and biological activities of S. pallidum polysaccharide were investigated. Under the optimal preparation condition, the average particle size, polydispersity index (PDI), and ξ-potential of nSPP-30 were 229.63 nm, 0.407, and -28.43 mV, respectively. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses indicated that nanocrystallization did not change primary and crystal structures of S. pallidum polysaccharide. However, nanocrystallization could improve the swelling, thermodynamic, and antioxidant properties of S. pallidum polysaccharide. In addition, the thymol adsorption capacity of nSPP-30 was enhanced as compared to the corresponding polysaccharide. These results suggest that nSPP-30 can be developed as a potential antioxidant or natural nano-carrier to encapsulate thymol for practical applications.

Chemical Characterization, Antitumor, and Immune-Enhancing Activities of Polysaccharide from Sargassum pallidum

Searching for natural products with antitumor and immune-enhancing activities is an important aspect of cancer research. Sargassum pallidum is an edible brown alga that has been used in Chinese traditional medicine for the treatment of tumors. However, the purification and application of its active components are still insufficient. In the present study, the polysaccharides from S. pallidum (SPPs) with antitumor and immune-enhancing activities were isolated and purified, and five polysaccharide fractions (SPP-0.3, SPP-0.5, SPP-0.7, SPP-1, and SPP-2) were obtained. The ratio of total saccharides, monosaccharide composition, and sulfated contents was determined, and their structures were analyzed by Fourier transform infrared spectroscopy. Moreover, bioactivity analysis showed that all five fractions had significant antitumor activity against three types of cancer cells (A549, HepG2, and B16), and can induce cancer cell apoptosis. In addition, the results indicated that SPPs can enhance the proliferation of immune cells and improve the expression levels of serum cytokines (IL-6, IL-1β, iNOS, and TNF-α). SPP-0.7 was identified as the most active fraction and selected for further purification, and its physicochemical properties and antitumor mechanism were further analyzed. Transcriptome sequencing result showed that SPP-0.7 can significantly induce the cell apoptosis, cytokine secretion, and cellular stress response process, and inhibit the normal physiological processes of cancer cells. Overall, SPPs and SPP-0.7 may be suitable for use as potential candidate agents for cancer therapy.

Preparation and characterization of chitosan-based edible active films incorporated with Sargassum pallidum polysaccharides by ultrasound treatment

In this study, Sargassum pallidum polysaccharides (SPPs) were incorporated into chitosan (CH) to develop a novel edible active film (CH/SPPs-US) via ultrasonication. The mechanical, water vapor permeability, surface morphology, crystallinity, antioxidant, and fruit preservation properties of CH/SPPs-US films prepared under sequences of matrix ratios and ultrasound treatment were investigated. The results revealed that the addition of SPPs combined with ultrasonic treatment could significantly enhance the transparency, elongation and tensile strength of the films whereas the water vapor permeability was decreased. Tensile strength and elongation at break of the C2/SP1.2-US film were 12.07 N and 54.18%, respectively, which were significantly higher than those for CH film. Meanwhile, the water vapor permeability value of C2/SP1.2-US was reduced by as high as 40.2% compared with that of chitosan film. In addition, antioxidant effect evaluation showed that the CH-based films added with SPPs exhibited better antioxidant activity than CH film, and ultrasonic treatment could further strengthen the antioxidant activity of the film. The CH/SPPs-US films could effectively extend the shelf life and inhibit the deterioration of the strawberry at room temperature (25 ± 1 °C) and 70% ± 5% relative humidity for 7 days. These results indicated that the CH/SPPs edible films via ultrasonication could be developed as edible packaging films for the preservation of fresh fruits.

Changes of digestive and fermentation properties of Sargassum pallidum polysaccharide after ultrasonic degradation and its impacts on gut microbiota

The in vitro digestive and fermentation properties of Sargassum pallidum polysaccharide (SPP) after ultrasound degradation were investigated. The results showed that SPP and its degraded fractions were not affected by human saliva, but slightly degraded by breaking glycosidic bonds under simulated gastrointestinal digestion. The DPPH radical scavenging activity, α-glucosidase inhibitory activity, and bile acid-binding capacity of SPP and its degraded fractions were decreased after digestion, which was attributed to the reduction of molecular weights (MWs) and viscosity. Furthermore, in vitro fermentation assay indicated that SPP and its degraded fractions showed good fermentability. The predominant compositional monosaccharides including arabinose, galactose, glucose, xylose, and uronic acid were significantly decreased, and the degraded SPP fractions were more easily fermented and utilized by gut bacteria. SPP and its degraded fractions could modulate gut health by decreasing the Firmicutes/Bacteroidetes ratio and increasing the relative abundances of some beneficial genera, such as Prevotella, Dialister, Phascolarctobacterium, Ruminococcus, and Bacteroides. These findings suggested that SPP and its degraded fractions exhibited similar influence on gut microbiota community, but appropriate degraded SPP fractions were more easily fermented by gut microbiota.

Sulfated modification, characterization, antioxidant and hypoglycemic activities of polysaccharides from Sargassum pallidum

The aim of this study was to investigate the effect of sulfated modification on the in vitro antioxidant and hypoglycemic activities of Sargassum pallidum polysaccharides (SPP). Three sulfated derivatives (S-SPP1-4, S-SPP1-6 and S-SPP1-8) were prepared using chlorosulfonic acid-pyridine method under different reaction conditions. Physicochemical characterization indicated that sulfated modification had successfully occurred. The degrees of substitution (DS) of S-SPP1-4, S-SPP1-6 and S-SPP1-8 were determined to be ranging from 0.85 to 1.19. Sulfated modification resulted in some changes in chemical component, molecular weight and monosaccharide composition of SPP. Among these sulfated polysaccharides, S-SPP1-4 exhibited the best DPPH and ABTS radical scavenging activities, while S-SPP1-8 exhibited the best α-glucosidase inhibitory activity and promoting-effect on glucose consumption in insulin resistant (IR)-HepG2 cells. Furthermore, all the sulfated derivatives exhibited better hypoglycemic ability than native SPP. These results suggest that appropriately sulfated modification could enhance the antioxidant and hypoglycemic activities of S. pallidum polysaccharides, which might be used as an alternative derivative of natural antioxidant and hypoglycemic agent.

Fractionation, preliminary structural characterization and bioactivities of polysaccharides from Sargassum pallidum

Sargassum pallidum polysaccharides were fractioned using a DEAE-Sepharose fast-flow column and four polysaccharide fractions (SP-P1, SP-P2, PV-P3 and SP-P4) were obtained. Structural analyses indicated that SP-P2 and SP-P4 had higher molecular weights than SP-P1 and SP-P3. SP-P2, SP-P3 and SP-P4 comprised of fucose, rhamnose, arabinose, galactose, glucose, xylose, and mannose in a similar molar ratio, while SP-P1 did not contain arabinose. SP-P2 and SP-P4 had a similar number of (1→6) or (1→) glycosidic linkages (1→2) or (1→4) glycosidic linkages and (1→3) glycosidic linkages, while SP-P1 and SP-P3 contained a small number of (1→3) glycosidic linkages. SP-P2 exhibited better bioactivities than SP-P1, SP-P3 and SP-P4, including antioxidant, anti-hemolysis inhibitory, α-amylase and α-glucosidase inhibitory and antiproliferative activities. These data suggest that S. pallidum has four polysaccharide fractions with different structural features and bioactivities and SP-P2 has potential to be explored as a functional food or complementary medicine.

Pharmacokinetic properties of arsenic species after oral administration of Sargassum pallidum extract in rats using an HPLC-HG-AFS method

Sargassum pallidum is one of the Traditional Chinese Medicine widely used for phlegm elimination and detumescence. Arsenic is present in high concentration in seaweed belonging to the genus Sargassum. Therefore, the consumption of S. pallidum is a route of exposure to arsenic. Since the toxicity of arsenic is highly dependent on its chemical speciation, the determination of total arsenic is not adequate to assess the risks. Here, a high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) was developed for determination of the common arsenic species including arsenite [As(III)], dimethylarsinate (DMA), methylarsonate (MMA) and arsenate [As(V)] simultaneously. This method was applied to study the pharmacokinetic profile of these arsenic species in rats after oral administration of S. pallidum extract at different doses. The described assay was validated for limit of quantification, linearity, intra-day and inter-day precisions, accuracy, extraction recovery and stability according to the FDA validation guidelines. As(III) or MMA was not detected in any samples collected at all time points using the present HPLC-HG-AFS method. As(V) and DMA in the S. pallidum could be readily absorbed and eliminated in rats. A trend of dose-dependence was shown for DMA and As(V) in the drug concentration-time profiles. This study would be helpful for the apprehension of the action mechanism and clinical application of medicinal seaweeds.

Structural elucidation of polysaccharide fractions from brown seaweed Sargassum pallidum

The structural characteristics of two purified fractions of polysaccharides from Sargassum pallidum (SPS) were investigated in the present study. As results, the molecular weights of the two polysaccharide fractions, SPS-3-1 and SPS-3-2, were determined to be 5.87 and 7.25 kDa, respectively. SPS-3-1 was composed of glucose, mannose and galactose in a molar ratio of 11.18:1.00:0.96, while SPS-3-2 was composed of fucose, xylose, mannose, glucose and galactose in a molar ratio of 2.53:0.61:1.00:0.46:0.92. Both SPS-3-1 and SPS-3-2 exhibited the characteristics of polysaccharide in the frequency range of 4000-400 cm(-1) based on their Fourier-transform infrared spectra. Furthermore, the results of periodic acid oxidation, Smith degradation, methylation analysis and nuclear magnetic resonance spectroscopic analysis suggested that SPS-3-2 was composed of (1→4)-linked fucopyranosyl backbone and (1→3)-linked galactopyranosyl, (1→3)-linked mannopyranosyl, (1→2)-linked xylopyranosyl and (1→6)-linked glucopyranosyl branch chains.