All-polysaccharide, self-healing, pH-sensitive, in situ-forming hydrogel of carboxymethyl chitosan and aldehyde-functionalized hydroxyethyl cellulose.

In situ forming hydrogels are promising for biomedical applications, especially in drug delivery. The precursor solution can be injected at the target site, where it undergoes a sol-gel transition to afford a hydrogel. In this sense, the most significant characteristic of these hydrogels is fast gelation behavior after injection. This study describes an all-polysaccharide, rapidly in situ-forming hydrogel composed of carboxymethyl chitosan (CMCHT) and hydroxyethyl cellulose functionalized with aldehyde groups (HEC-Ald). The HEC-Ald was synthesized through acetal functionalization, followed by acid deprotection. This innovative approach avoids cleavage of pyran rings, as is inherent in the periodate oxidation approach, which is the most common method currently employed for adding aldehyde groups to polysaccharides. The resulting hydrogel exhibited fast stress relaxation, self-healing properties, and pH sensitivity, which allowed it to control the release of an encapsulated model drug in response to the medium pH. Based on the collected data, the HEC-Ald/CMCHT hydrogels show promise as pH-sensitive drug carriers.

Structural variety of glucans from Ganoderma lucidum fruiting bodies.

Ganoderma lucidum, widely used in traditional medicine, has several biological properties. Polysaccharides, mainly glucans, are known as one of its main bioactive compounds. Consequently, the achievement and chemical investigation of such molecules are of pharmaceutical interest. Herein, we obtained water-insoluble and water-soluble polysaccharides from G. lucidum by alkaline extraction. Fractionation process yielded three fractions (GLC-1, GLC-2, and GLC-3). All samples showed to be composed mainly of glucans. GLC-1 is a linear (1 â†’ 3)-linked ß-glucan; GLC-2 is a mixture of three different linear polysaccharides: (1 â†’ 3)-ß-glucan, (1 â†’ 3)-α-glucan, and (1 â†’ 4)-α-mannan; while GLC-3 is a branched ß-glucan with a (1 â†’ 4)-linked main chain, which is branched at O-3 or O-6 by (1 â†’ 3)- or (1 â†’ 6)-linked side chains. This research reports the variability of glucans in Ganoderma lucidum fruiting bodies and applicable methodologies to obtain such molecules. These polysaccharides can be further applied in biological studies aiming to investigate how their chemical differences may affect their biological properties.

(1 → 3),(1 → 6) and (1 → 3)-ß-D-glucan physico-chemical features drive their fermentation profile by the human gut microbiota.

Mushroom polysaccharides consist of a unique set of polymers that arrive intact in the human large intestine becoming available for fermentation by resident gut bacteria with potential benefits to the host. Here we have obtained four glucans from two mushrooms (Pholiota nameko and Pleurotus pulmonarius) under different extraction conditions and their fermentation profile by human gut bacteria in vitro was evaluated. These glucans were isolated and characterized as (1 â†’ 3),(1 â†’ 6)-ß-D-glucans varying in branching pattern and water-solubility. An aliquot of each (1 â†’ 3),(1 â†’ 6)-ß-D-glucan was subjected to controlled smith degradation process in order to obtain a linear (1 â†’ 3)-ß-D-glucan from each fraction. The four ß-D-glucans demonstrated different water solubilities and molar mass ranging from 2.2 × 105 g.mol-1 to 1.9 × 106 g.mol-1. In vitro fermentation of the glucans by human gut microbiota showed they induced different short chain fatty acid production (52.0-97.0 mM/50 mg carbohydrates), but an overall consistent high propionate amount (28.5-30.3 % of total short chain fatty acids produced). All glucans promoted Bacteroides uniformis, whereas Anaerostipes sp. and Bacteroides ovatus promotion was strongly driven by the ß-D-glucans solubility and/or branching pattern, highlighting the importance of ß-D-glucan discrete structures to their fermentation by the human gut microbiota.

Antimelanoma effect of a fucoxylomannan isolated from Ganoderma lucidum fruiting bodies.

A fucoxylomannan (FXM) was isolated from the mushroom Ganoderma lucidum through alkaline extraction followed by dialysis, freeze-thawing, and fractionation by Fehling's solution. The main chain of FXM presented α-d-Manp-(1→4)-linked units, and some of them were branched at O-6 position by α-l-Fucp-(1→2)-ß-d-Xylp groups. Its Mw was 35.9 kDa. FXM was tested on melanoma B16-F10 cells and it showed cell viability and cell density reduction, as well as antiproliferative effect, through cell cycle arrest. Additionally, the anchorage-independent clonogenic capacity of such cells was significantly reduced by FXM, decreasing the number of cells by colony and the colonies area. No effect on viability neither in proliferation of non-tumoral Balb c/3T3 fibroblasts was observed. These results indicate that FXM is a promising anti-proliferative compound impairing pivotal tumorigenic mechanisms, eliciting this polysaccharide to be further explored as an antimelanoma drug.

An α-D-galactan and a ß-D-glucan from the mushroom Amanita muscaria: Structural characterization and antitumor activity against melanoma.

Polysaccharides α-D-galactan (GAL-Am) and ß-D-glucan (GLC-Am) were obtained from Amanita muscaria fruiting bodies. They were purified using different methodologies, such as Fehling precipitation (for both fractions), freeze-thawing process and ultrafiltration (for GLC-Am). Results showed that the GAL-Am has (1 â†’ 6)-linked Galp main chain branched at O-2 by terminal Galp units and has not been previously reported. Besides, GLC-Am has (1 â†’ 3)-linked Glcp in the main chain, substituted at O-6 by (1 â†’ 6)-linked ß-Glcp units. Both are water-soluble, with 9.0 × 103 g/moL and 1.3 × 105 g/moL, respectively. GAL-Am and GLC-Am presented a selective proliferation reduction against B16-F10 melanoma cell line, not affecting non tumoral BALB/3T3 fibroblast cell line. Furthermore, both fractions reduced clonogenic capacity of melanoma cell line over an extended period of time. These results were obtained without modulations in B16-F10 cell adhesion, reinforcing the biological activities towards cell proliferation impairment and eliciting these polysaccharides as promising compounds to further exploration of their antimelanoma properties.

Polysaccharides from Pleurotus eryngii: Selective extraction methodologies and their modulatory effects on THP-1 macrophages.

Polysaccharides from P. eryngii mushroom were selectively extracted using low-cost technologies (water at different conditions of temperature and pressure). Mannogalactan was the main polysaccharide in cold-water extracted fraction (CWEF), while a linear (1→6)-ß-d-glucan was the main polymer in hot-water extracted fraction (HWEF). Autoclave-extracted fraction (AEF) contained a mixture of at least four different α- and ß-glucans. The report of linear (1→6)-ß-glucan and linear (1→3)-ß-glucan is a new finding for P. eryngii fruiting bodies. The immunostimulatory properties of the fractions on THP-1 macrophages were studied. All fractions at 50, 250 and 500 µg/mL were not cytotoxic and produced different stimulus on NO, IL-1ß and IL-10 secretion by the cells. Thus, our results showed that it is possible to concentrate different P. eryngii polysaccharides in selected fractions using a simple and low-cost procedure. Since biological effects depends on the polysaccharide structure, this technique allows the obtainment of fractions with distinct immunomodulatory activities.