Conjugation of metronidazole with dextran: a potential pharmaceutical strategy to control colonic distribution of the anti-amebic drug susceptible to metabolism by colonic microbes

Impact of Lyophilized Milk Kefir-Based Self-Nanoemulsifying System on Cognitive Enhancement via the Microbiota-Gut-Brain Axis

Chronic inflammatory bowel disorders (IBDs) are characterized by altered intestinal permeability, prompting inflammatory, oxidative stress, and immunological factors. Gut microbiota disorders impact brain function via the bidirectional gut-brain axis, influencing behavior through inflammatory cascades, oxidative stress, and neurotransmitter levels. This study highlights the potential effect of integrating lyophilized milk kefir alone and lyophilized milk kefir as solid carriers loaded with a self-nanoemulsifying self-nanosuspension (SNESNS) of licorice extract on an induced chronic IBD-like model in rats. Licorice-SNESNS was prepared by the homogenization of 30 mg of licorice extract in 1 g of the selected SNEDDS (30% Caraway oil, 60% Tween 20, and 10% propylene glycol (w/w)). Licorice-SNESNS was mixed with milk kefir and then freeze-dried. Dynamic TEM images and the bimodal particle size curve confirmed the formation of the biphasic nanosystems after dilution (nanoemulsion and nanosuspension). Daily oral administration of lyophilized milk kefir (100 mg/kg) loaded with SNESNS (10 mg/kg Caraway oil and 1 mg/kg licorice) restored normal body weight and intestinal mucosa while significantly reducing submucosal inflammatory cell infiltration in induced rats. Importantly, this treatment demonstrated superior efficacy compared to lyophilized milk kefir alone by leading to a more significant alleviation of neurotransmitter levels and improved memory functions, thereby addressing gut-brain axis disorders. Additionally, it normalized fecal microbiome constituents, inflammatory cytokine levels, and oxidative stress in examined tissues and serum. Moreover, daily administration of kefir-loaded SNESNS normalized the disease activity index, alleviated histopathological changes induced by IBD induction, and partially restored the normal gut microbiota. These alterations are associated with improved cognitive functions, attributed to the maintenance of normal neurotransmitter levels and the alleviation of triggered inflammatory factors and oxidative stress levels.

Dextran Formulations as Effective Delivery Systems of Therapeutic Agents

Dextran is by far one of the most interesting non-toxic, bio-compatible macromolecules, an exopolysaccharide biosynthesized by lactic acid bacteria. It has been extensively used as a major component in many types of drug-delivery systems (DDS), which can be submitted to the next in-vivo testing stages, and may be proposed for clinical trials or pharmaceutical use approval. An important aspect to consider in order to maintain high DDS' biocompatibility is the use of dextran obtained by fermentation processes and with a minimum chemical modification degree. By performing chemical modifications, artefacts can appear in the dextran spatial structure that can lead to decreased biocompatibility or even cytotoxicity. The present review aims to systematize DDS depending on the dextran type used and the biologically active compounds transported, in order to obtain desired therapeutic effects. So far, pure dextran and modified dextran such as acetalated, oxidised, carboxymethyl, diethylaminoethyl-dextran and dextran sulphate sodium, were used to develop several DDSs: microspheres, microparticles, nanoparticles, nanodroplets, liposomes, micelles and nanomicelles, hydrogels, films, nanowires, bio-conjugates, medical adhesives and others. The DDS are critically presented by structures, biocompatibility, drugs loaded and therapeutic points of view in order to highlight future therapeutic perspectives.

Oral delivery of natural active small molecules by polymeric nanoparticles for the treatment of inflammatory bowel diseases

The incidence of inflammatory bowel disease (IBD) is rapidly rising throughout the world. Although tremendous efforts have been made, limited therapeutics are available for IBD management. Natural active small molecules (NASMs), which are a gift of nature to humanity, have been widely used in the prevention and alleviation of IBD; they have numerous advantageous features, including excellent biocompatibility, pharmacological activity, and mass production potential. Oral route is the most common and acceptable approach for drug administration, but the clinical application of NASMs in IBD treatment via oral route has been seriously restricted by their inherent limitations such as high hydrophobicity, instability, and poor bioavailability. With the development of nanotechnology, polymeric nanoparticles (NPs) have provided a promising platform that can efficiently encapsulate versatile NASMs, overcome multiple drug delivery barriers, and orally deliver the loaded NASMs to targeted tissues or cells while enhancing their stability and bioavailability. Thus, NPs can enhance the preventive and therapeutic effects of NASMs against IBD. Herein, we summarize the recent knowledge about polymeric matrix-based carriers, targeting ligands for drug delivery, and NASMs. We also discuss the current challenges and future developmental directions.

Preparation, development and characterization of Leucaena leucocephala galactomannan (LLG) conjugated sinapic acid: A potential colon targeted prodrug

Sinapic acid (SA), a widely prevalent hydroxycinnamic acid, possess numerous biological activities owing to its antioxidant property. The present study was aimed to prepare colon targeted polysaccharidic/polymeric ester prodrug of SA (a microbially triggered system) using Leucaena leucocephala galactomannan (LLG) as a polysaccharidic carrier. The polymeric conjugates of SA-LLG were found to exhibit an increase in % yield and DS with increase in amount of SA and volume of thionyl chloride. The degree of depolymerization of SA-LLG prodrug batches were evaluated using optimized concentration of galactomannase. The SA-LLG prodrug was characterized employing UV and FTIR spectroscopy, ¹H NMR and XRD. In vitro release study of the optimized prodrug batch (SL10) suggested stable nature of SA-LLG conjugate under acidic (pH 1.2) and alkaline conditions (pH 6.8). The treatment of prodrug with galactomannase (15 mg/mL) followed by esterase (10 U/mL) enzyme released approximately 81% of SA after 24 h. The cell viability results revealed that free SA and SA-LLG were found to have similar antiproliferative potential against human colon cancer cell lines (HCT-116 cells). Our investigation revealed that polysaccharidic prodrug, SA-LLG, has the potential for colon targeting of SA and thus can be employed for the treatment of Inflammatory Bowel Diseases (IBDs).

A hybrid polymer to target blood group dependence of cholera toxin

New hybrid glycopolymers were synthesized that contain two epitopes blocking GM1- and fucose-based intoxication modes of the cholera toxin.

Preparation and application of dextran and its derivatives as carriers

As a natural and renewable biological macromolecule, dextran not only has excellent biodegradability, but also has good biocompatibility. Dextran and its derivatives are functional polymers for the construction of targeted drug delivery systems. Herein, the application of dextran as prodrug and nanoparticle/nanogel/microsphere/micelle carrier for targeting drug delivery system was summarized. It is clarified that dextran is an important biomaterial with application value.

Strong Inhibition of Cholera Toxin B Subunit by Affordable, Polymer-Based Multivalent Inhibitors

Cholera is a potentially fatal bacterial infection that affects a large number of people in developing countries. It is caused by the cholera toxin (CT), an AB₅ toxin secreted by Vibrio cholera. The toxin comprises a toxic A-subunit and a pentameric B-subunit that bind to the intestinal cell surface. Several monovalent and multivalent inhibitors of the toxin have been synthesized but are too complicated and expensive for practical use in developing countries. Meta-nitrophenyl α-galactoside (MNPG) is a known promising ligand for CT, and here mono- and multivalent compounds based on MNPG were synthesized. We present the synthesis of MNPG in greatly improved yields and its use while linked to a multivalent scaffold. We used economical polymers as multivalent scaffolds, namely, polyacrylamide, dextran, and hyperbranched polyglycerols (hPGs). Copper-catalyzed alkyne azide cycloaddition reaction (CuAAC) produced the inhibitors that were tested in an ELISA-type assay and an intestinal organoid swelling inhibition assay. The inhibitory properties varied widely depending on the type of polymer, and the most potent conjugates showed IC₅₀ values in the nanomolar range.