Anti-obesity effects of enzymatically-digested alginate oligomer in mice model fed a high-fat-diet

A concise synthesis of l-gulose and its C-6 derivatives

A convenient route for the preparation of l-gulose and its C-6 derivatives starting from commercially available 2,3:5,6-diisopropylidene-d-mannofuranose via C-5 epimerization as the key step was developed. 1-O-Benzylation followed by regioselective hydrolysis of the 5,6-isopropylidene group furnished benzyl 2,3-isopropylidene-α-d-mannofuranoside, which was subjected upon regioselective one-pot 6-O-benzoylation and 5-O-mesylation, providing the corresponding 5-OMs-6-OBz derivative in excellent selectivity. Treatment of this mesylate compound with potassium t-butoxide to remove the benzoyl group followed by intramolecular S_N2 inversion led to benzyl 5,6-anhydro-2,3-isopropylidene-β-l-gulofuranoside, which could undergo not only nucleophilic substitutions to open the epoxide ring to give various C-6 derivatives, but also acidic hydrolysis to yield 1,6-anhydro-β-l-gulopyranose for further transformation into l-gulopyranosyl pentaacetate.

Biomaterials from the sea: Future building blocks for biomedical applications

Marine resources have tremendous potential for developing high-value biomaterials. The last decade has seen an increasing number of biomaterials that originate from marine organisms. This field is rapidly evolving. Marine biomaterials experience several periods of discovery and development ranging from coralline bone graft to polysaccharide-based biomaterials. The latter are represented by chitin and chitosan, marine-derived collagen, and composites of different organisms of marine origin. The diversity of marine natural products, their properties and applications are discussed thoroughly in the present review. These materials are easily available and possess excellent biocompatibility, biodegradability and potent bioactive characteristics. Important applications of marine biomaterials include medical applications, antimicrobial agents, drug delivery agents, anticoagulants, rehabilitation of diseases such as cardiovascular diseases, bone diseases and diabetes, as well as comestible, cosmetic and industrial applications.

Potential applications of alginate oligosaccharides for biomedicine - A mini review

Extensive research on marine algae, especially on their health-promoting properties, has been conducted. Various ingredients with potential biomedical applications have been discovered and extracted from marine algae. Alginate oligosaccharides are low molecular weight alginate polysaccharides present in cell walls of brown algae. They exhibit various health benefits such as anti-inflammatory, anti-microbial, anti-oxidant, anti-tumor and immunomodulation. Their low-toxicity, non-immunogenicity, and biodegradability make them an excellent material in biomedicine. Alginate oligosaccharides can be chemically or biochemically modified to enhance their biological activity and potential in pharmaceutical applications. This paper provides a brief overview on alginate oligosaccharides characteristics, modification patterns and highlights their vital health promoting properties.

Implementation and in vitro characterization of calcium-free in situ gelling oral reconstituted suspension for potential overweight treatment

In this work, oral granules that were easily dissolved in aqueous dispersion, were prepared. These oral suspensions were formulated with sodium alginate (AlgNa), chitosan (CHI) and sodium carboxymethylcellulose (CMC Na). The gels were formulated by pouring the suspensions into 150 ml of simulated gastric fluid (SGF) pH 1.2 at 37° C. The in-situ gelling mechanism was based on the ionization states of the three biopolymers as a function of the pH of the medium. Fourier transform infrared analysis of gels confirmed the interactions between alginate and chitosan. According to the scanning electron microscopy analysis, the gels were characterized by a firm and homogeneous structure. The obtained values of the elastic storage modulus, G', varied between 10 1   and 10 7 Pa. The eliminated volume of the unabsorbed liquid by the gels fluctuated between 25% and 55% of the total liquid volume. The quality of the gels was improved when a maximum concentration of alginate ( 4   g / 100   ml ) , a minimum concentration of chitosan ( 0.5   g / 100   ml ) and a maximum amount of carboxymethylcellulose ( 4   g / 100   ml ) were used. The value of their elastic modulus, G' was around 10 5 Pa and the residual unabsorbed volume of the liquid was 25% of the total liquid volume. According to the obtained results, the prepared gels could induce a feeling of fullness by stimulating the gastric distension and they could potentially be applied as anti-obesity medication.

Bioactive Polysaccharides from Seaweeds

Bioactive compounds with diverse chemical structures play a significant role in disease prevention and maintenance of physiological functions. Due to the increase in industrial demand for new biosourced molecules, several types of biomasses are being exploited for the identification of bioactive metabolites and techno-functional biomolecules that are suitable for the subsequent uses in cosmetic, food and pharmaceutical fields. Among the various biomasses available, macroalgae are gaining popularity because of their potential nutraceutical and health benefits. Such health effects are delivered by specific diterpenes, pigments (fucoxanthin, phycocyanin, and carotenoids), bioactive peptides and polysaccharides. Abundant and recent studies have identified valuable biological activities of native algae polysaccharides, but also of their derivatives, including oligosaccharides and (bio)chemically modified polysaccharides. However, only a few of them can be industrially developed and open up new markets of active molecules, extracts or ingredients. In this respect, the health and nutraceutical claims associated with marine algal bioactive polysaccharides are summarized and comprehensively discussed in this review.

Seaweed-derived bioactives as potential energy regulators in obesity and type 2 diabetes

There is epidemiological evidence that dietary intake of seaweeds is associated with a lower prevalence of chronic diseases. While seaweeds are of high nutritious value, due to their high content of fiber, polyunsaturated fatty acids and minerals, they also contain an abundance of bioactive compounds. There is a growing body of scientific data that these bioactive moieties exert effects that could correct the metabolic dysregulation that is present in obesity and Type 2 diabetes (T2D). In this review we describe how the molecular mechanisms, specific to different tissues, that underly obesity and T2D are influenced by both seaweed extracts and seaweed-derived bioactive molecules. In obesity, modulation of antioxidant capacity and reduction of intracellular ROS levels within tissues, and regulation of signaling pathways involved in enhancing browning of white adipose tissue, have been highlighted as key mechanism and identified as a potential target for optimal energy metabolism. In T2D, management of post-prandial blood glucose by modulating α-glucosidase or α-amylase activities, modulation of the AMPK signaling pathway, and similarly to obesity, reduction of ROS and NO production with subsequent increased expression of antioxidant enzymes have been shown to play a key role in glucose metabolism and insulin signaling. Future studies aimed at discovering new therapeutic drugs from marine natural products should, therefore, focus on bioactive compounds from seaweed that exert antioxidant activity and regulate the expression of key signaling pathways involved in glucose homeostasis, mechanisms that are common to both obesity and T2D management. In addition, more data is required to provide evidence of clinical benefit.

Alginate oligosaccharide (AOS) improves immuno-metabolic systems by inhibiting STOML2 overexpression in high-fat-diet-induced obese zebrafish

AOS improves immuno-metabolism systems in high-fat-died-induced obese zebrafish by regulating STOML2.

A Neuro-Comparative Study between Single/Successive Thorium Dose Intoxication and Alginate Treatment

The adult male albino rats were grouped into five groups (control group and four variably treated groups with thorium (Th) in single or successive with or without alginate treatment). The IP administration of thorium nitrate (13.6 mg/kg b.wt.) induced a regional distribution and accumulation ordered as cerebellum > cerebral cortex > brain stem > hippocampus > hypothalamus > striatum. Also, it induces a significant increase in Na⁺, Ca²⁺, and Fe³⁺ ion content and malondialdehyde (MDA) level while K⁺ ions and glutathione (GSH) level were significantly decreased. On the other hand, the daily oral administration of 5% alginate showed a significant decreasing in the accumulation of thorium in the different brain areas and mitigated its hazardous effects. By the alginate treatment, Na⁺, Ca²⁺, Fe³⁺, and level of MDA were declined while K⁺ ions and GSH level showed a significant increase. The improvement of the investigated parameters was attributed to the specific chelating, regeneration, and antioxidant properties of the alginate. So, alginate administration could ameliorate the hazardous effects of thorium nitrate.

Overview on the Antihypertensive and Anti-Obesity Effects of Secondary Metabolites from Seaweeds

Hypertension and obesity are two significant factors that contribute to the onset and exacerbation of a cascade of mechanisms including activation of the sympathetic and renin-angiotensin systems, oxidative stress, release of inflammatory mediators, increase of adipogenesis and thus promotion of systemic dysfunction that leads to clinical manifestations of cardiovascular diseases. Seaweeds, in addition to their use as food, are now unanimously acknowledged as an invaluable source of new natural products that may hold noteworthy leads for future drug discovery and development, including in the prevention and/or treatment of the cardiovascular risk factors. Several compounds including peptides, phlorotannins, polysaccharides, carotenoids, and sterols, isolated from brown, red and green macroalgae exhibit significant anti-hypertensive and anti-obesity properties. This review will provide a comprehensive overview of the recent advances on bioactive pure compounds isolated from different seaweed sources focusing on their potential use as drugs to treat or prevent hypertension and obesity. On the other hand, although it is obvious that macroalgae represent promising sources of antihypertensive and anti-obesity compounds, it is also clear that further efforts are required to fully understand their cellular mechanisms of action, to establish structure-inhibition relationships and mainly to evaluate them in pre-clinical and clinical trials.

Effects of alginate oligomer on the expression of cell cycle- and stress-related genes in Chlamydomonas reinhardtii

Enzymatically prepared alginate oligomer (AO) promoted the growth of Chlamydomonas reinhardtii in a concentration-dependent manner. AO at 2.5 mg/mL induced increase in expression levels of cyclin A, cyclin B, and cyclin D in C. reinhardtii. CuSO₄ at 100 μM suppressed the growth of C. reinhardtiin, and AO at 2.5 mg/mL significantly alleviated the toxicity of CuSO₄. Increased intracellular reactive oxygen species level in C. reinhardtii induced by CuSO₄ was reduced by AO. After cultivation with CuSO₄ at 100 μM, expression levels of ascorbate peroxidase and superoxide dismutase in C. reinhardtii were increased, and AO reduced the increased levels of these enzymes. These results suggest that AO exhibits beneficial effects on C. reinhardtii through influencing the expression of various genes not only at normal growth condition but also under CuSO₄ stress.

Marine Algae as a Potential Source for Anti-Obesity Agents

Obesity is a major epidemic that poses a worldwide threat to human health, as it is also associated with metabolic syndrome, type 2 diabetes and cardiovascular disease. Therapeutic intervention through weight loss drugs, accompanied by diet and exercise, is one of the options for the treatment and management of obesity. However, the only approved anti-obesity drug currently available in the market is orlistat, a synthetic inhibitor of pancreatic lipase. Other anti-obesity drugs are still being evaluated at different stages of clinical trials, while some have been withdrawn due to their severe adverse effects. Thus, there is a need to look for new anti-obesity agents, especially from biological sources. Marine algae, especially seaweeds are a promising source of anti-obesity agents. Four major bioactive compounds from seaweeds which have the potential as anti-obesity agents are fucoxanthin, alginates, fucoidans and phlorotannins. The anti-obesity effects of such compounds are due to several mechanisms, which include the inhibition of lipid absorption and metabolism (e.g., fucoxanthin and fucoidans), effect on satiety feeling (e.g., alginates), and inhibition of adipocyte differentiation (e.g., fucoxanthin). Further studies, especially testing bioactive compounds in long-term human trials are required before any new anti-obesity drugs based on algal products can be developed.

Looking Beyond the Terrestrial: The Potential of Seaweed Derived Bioactives to Treat Non-Communicable Diseases

Seaweeds are a large and diverse group of marine organisms that are commonly found in the maritime regions of the world. They are an excellent source of biologically active secondary metabolites and have been shown to exhibit a wide range of therapeutic properties, including anti-cancer, anti-oxidant, anti-inflammatory and anti-diabetic activities. Several Asian cultures have a strong tradition of using different varieties of seaweed extensively in cooking as well as in herbal medicines preparations. As such, seaweeds have been used to treat a wide variety of health conditions such as cancer, digestive problems, and renal disorders. Today, increasing numbers of people are adopting a "westernised lifestyle" characterised by low levels of physical exercise and excessive calorific and saturated fat intake. This has led to an increase in numbers of chronic Non-communicable diseases (NCDs) such as cancer, cardiovascular disease, and diabetes mellitus, being reported. Recently, NCDs have replaced communicable infectious diseases as the number one cause of human mortality. Current medical treatments for NCDs rely mainly on drugs that have been obtained from the terrestrial regions of the world, with the oceans and seas remaining largely an untapped reservoir for exploration. This review focuses on the potential of using seaweed derived bioactives including polysaccharides, antioxidants and fatty acids, amongst others, to treat chronic NCDs such as cancer, cardiovascular disease and diabetes mellitus.