Carbohydrate Polymers / Inhibition of P-glycoprotein-mediated efflux by thiolated cyclodextrins

Overcoming P-glycoprotein (P-gp)-mediated efflux poses a significant challenge for the pharmaceutical industry. This study investigates the potential of thiolated \u3b2-cyclodextrins (\u3b2-CD-SHs) as inhibitors of P-gp-mediated efflux in Caco-2 cells. Through a series of transport assays, intracellular accumulation, and efflux of the P-gp substrates Rhodamine 123 (Rh123) and Calcein-AM with and without co-administration of \u3b2-CD-SHs were assessed. The results revealed that the cellular uptake of Rh123 and Calcein-AM were enhanced up to 7- and 3-fold, compared to the control, respectively. In efflux studies an up to 2.5-fold reduction of the Rh123 efflux was reached compared the control, indicating a substantial decrease of Rh123 efflux by \u3b2-CD-SHs. Furthermore, it was observed that \u3b2-CD-SHs led to a decrease in the reactivity of fluorescence-labeled anti-P-gp, suggesting additional effects on the conformation of P-gp. Overall, this study demonstrates the potential of \u3b2-CD-SHs as effective modulator of P-gp-mediated drug efflux in Caco-2 cells.Version of recor

Ocular antibacterial chitosan-maleic acid hydrogels: In vitro and in vivo studies for a promising approach with enhanced mucoadhesion

The aim was to design and evaluate a chitosan-based conjugate providing high mucoadhesiveness and antibacterial activity for ocular infections treatment. Chitosan was conjugated with maleic acid via amide bond formation and infrared spectroscopy. Furthermore, 2,4,6-Trinitrobenzene sulfonic acid (TNBS) allowed characterization and quantification of conjugated groups, respectively. Biocompatibility was tested via hemolysis assay and Hen's Egg-Chorioallantoic membrane test. Characterization of the pH and osmolarity of hydrogels was followed by mucoadhesion assessment utilizing rheology. In addition, antibacterial studies were carried out towards Escherichia coli by broth microdilution test and agar-disk diffusion assay. In vivo studies were carried out following the already established Draize test and determining pharmacokinetic profile of dexamethasone in aqueous humour. The conjugate exhibited a degree of modification of 50.05 % and no toxicity or irritability. Moreover, mucoadhesive properties were enhanced in 2.68-fold and 1.81-fold for elastic and viscous modulus, respectively. Furthermore, rheological synergism revealed the presence of a gel-like structure. Additionally, broth microdilution and agar disk diffusion studies exhibited enhancement in antibacterial activity. Finally, in vivo studies manifested that hydrogels were highly tolerated, evidencing promising characteristics of the developed conjugate. The conjugate presented promising antimicrobial, long lasting mucoadhesive features and highly improved pharmacokinetics, leading to a revolutionizing approach in the treatment of ocular bacterial infections

Carbohydrate Polymers / Thiolated chitosans: are Cys-Cys ligands key to the next generation?

The potential of Cys-Cys ligands for the development of a novel type of S-protected thiomers was evaluated. S-protected thiomers chitosan-N-acetylcysteine-mercaptonicotinamide (CS-NAC-MNA) and chitosan-N-acetylcysteine-N-acetylcysteine (CS-NAC-NAC) were synthesized and characterized. Viscosity of polymers in presence of various concentrations of S-amino acids was monitored. Mucoadhesive properties were evaluated. FT-IR characterization confirmed the covalent attachment of NAC-MNA and NAC-NAC. Attached sulfhydryl groups were found in the range of 550 \u3bcmol/g. In the presence of amino acids bearing a free thiol group viscosity of both polymers increased. This increase in viscosity depended on the amount of added free thiols. Maximum force required to detach CS-NAC-MNA and CS-NAC-NAC from porcine intestinal mucosa was 1.4- and 2.7-fold higher than that required for chitosan, respectively. CS-NAC-MNA adhered up to 3 h, whereas CS-NAC-NAC adhered even for 8 h on this mucosa. Accordingly, the Cys-Cys substructure could be identified as highly potent ligand for the design of mucoadhesive polymers.Version of recor

Endophthalmitis therapy revolution: Proof of concept based on in vivo evaluation of maleic acid modified chitosan

The aim was to develop chitosan-maleic acid (CS-MA) based ocular inserts with enhanced mucoadhesiveness for prevention of endophthalmitis caused by Escherichia coli. Therefore, chitosan (CS) and maleic acid (MA) were conjugated via formation of amide bond. Characterization via proton nuclear magnetic resonance and infrared spectroscopy was carried out and attached maleic acid groups were quantified by free amino groups assay. Biocompatibility of the conjugate was assessed following resazurin assay on fibroblasts, membrane damage on human erythrocytes and Hen's Egg-Chorioallantoic membrane tests. Inserts were pressed and characterized in terms of swelling behavior, pH, hardness, in vitro drug release and disintegration. To test mucoadhesive properties of CS-MA inserts, rheometer, rotating cylinder, inclined plane, and texture analyzer were the instruments utilized. Furthermore, antibacterial efficacy of the conjugate was established by direct agar diffusion method and in vivo Draize test was carried out to determine tolerability of the inserts. Results exhibited successful synthesis of the biomaterial, maintaining the great biocompatibility of native chitosan even though a 68.81 % of modification was achieved. Additionally, mucoadhesive studies showed improved properties of CS-MA compared to native polymer, with 2.42-fold, 4-fold, 3.42-fold and 4.05-fold increase in dynamic viscosity, retention time, overall attachment work and peak force of detachment, respectively. Finally, antibacterial activity was enhanced in 1.77-fold and in vivo experiments showed no irritation and good tolerability of CS-MA inserts. In conclusion, CS-MA ocular inserts effectively developed exhibiting promising features capable of revolutionizing the endophthalmitis therapy field

ACS Applied Materials and Interfaces / Per-6-thiolated cyclodextrins: a novel type of permeation enhancing excipients for BCS class IV drugs

The purpose of the study was to develop a per-6-thiolated \u3b1[alpha]-cyclodextrin (\u3b1[alpha]-CD) by substituting all primary hydroxyl groups of \u3b1[alpha]-CD with thiol groups and to assess its solubility-improving and permeation-enhancing properties for a BCS Class IV drug in vitro as well as in vivo. The primary hydroxyl groups of \u3b1[alpha]-CD were replaced by iodine, followed by substitution with -SH groups. The structure of per-6-thiolated \u3b1[alpha]-CD was approved by FT-IR and 1H NMR spectroscopy. The per-6-thiolated was characterized for thiol content, -SH stability, cytotoxicity, and solubility-improving properties by using the model BCS Class IV drug furosemide (FUR). The mucoadhesive properties of the thiolated oligomer were investigated via viscoelastic measurements with porcine mucus, whereas permeation-enhancing features were evaluated on the Caco-2 cell monolayer and rat gut mucosa. Furthermore, oral bioavailability studies were performed in rats. The per-6-thiolated \u3b1[alpha]-CD oligomer displayed 4244 +/- 402 \u3bc[my]mol/g thiol groups. These -SH groups were stable at pH 64 4, exhibiting a pKa value of 8.1, but subject to oxidation at higher pH. Per-6-thiolated \u3b1[alpha]-CD was not cytotoxic to Caco-2 cells in 0.5% (m/v) concentration within 24 h. It improved the solubility of FUR in the same manner as unmodified \u3b1[alpha]-CD. The addition of per-6-thiolated \u3b1[alpha]-CD (0.5% m/v) increased the mucus viscosity up to 5.8-fold at 37 \ub0C within 4 h. Because of the incorporation in per-6-thiolated \u3b1[alpha]-CD, the apparent permeability coefficient (Papp) of FUR was 6.87-fold improved on the Caco-2 cell monolayer and 6.55-fold on the intestinal mucosa. Moreover, in vivo studies showed a 4.9-fold improved oral bioavailability of FUR due to the incorporation in per-6-thiolated \u3b1[alpha]-CD. These results indicate that per-6-thiolated \u3b1-CD would be a promising auxiliary agent for the mucosal delivery of, in particular, BCS Class IV drugs.Version of recor

European Journal of Pharmaceutical Sciences / Unveiling the potential of biomaterials and their synergistic fusion in tissue engineering

Inspired by nature, tissue engineering aims to employ intricate mechanisms for advanced clinical interventions, unlocking inherent biological potential and propelling medical breakthroughs. Therefore, medical, and pharmaceutical fields are growing interest in tissue and organ replacement, repair, and regeneration by this technology. Three primary mechanisms are currently used in tissue engineering: transplantation of cells (I), injection of growth factors (II) and cellular seeding in scaffolds (III). However, to develop scaffolds presenting highest potential, reinforcement with polymeric materials is growing interest. For instance, natural and synthetic polymers can be used. Regardless, chitosan and keratin are two biopolymers presenting great biocompatibility, biodegradability and non-antigenic properties for tissue engineering purposes offering restoration and revitalization. Therefore, combination of chitosan and keratin has been studied and results exhibit highly porous scaffolds providing optimal environment for tissue cultivation. This review aims to give an historical as well as current overview of tissue engineering, presenting mechanisms used and polymers involved in the field.Version of recor

Specific impairment of proximal tubular cell proliferation by a monoclonal κ light chain responsible for Fanconi syndrome.

International audienceBackground Fanconi syndrome (FS) is a rare renal disorder featuring proximal tubule dysfunction that may occur following tubular reabsorption of a monoclonal light chain (LC), in patients with multiple myeloma. FS may precede the recognition of multiple myeloma by several years. In most cases, crystalline inclusions of monoclonal κ LCs are observed within the lysosomes of proximal tubular cells (PTCs) and probably participate in their functional alteration. Methods To investigate the mechanism implicated in proximal tubule dysfunction, we compared the effects of κ LC-CHEB obtained from a patient with myeloma-associated FS to those of control κ LC-BON obtained from a patient without evidence of FS, on the viability and proliferation of two different PTC lines. Results Our data suggest that the tubular atrophy in myeloma-associated FS does not result from increased apoptosis of PTCs, but from their impaired capacity to proliferate and renew. Indeed, in vitro incubation of cultured PTCs with physiological amounts of the nephrotoxic κ LC-CHEB was sufficient to cause a depression in DNA synthesis and in cell proliferation. This effect was observed neither with control κ LC-BON nor in the absence of κ LC. Conclusions The reduced turnover of PTCs may affect tubular repair and regeneration. In addition, the reduced proliferation of myeloma cells producing the same monoclonal κ LC might explain the frequent association of FS with smoldering multiple myeloma