Katarzyna Winnicka

Stability of Chitosan—A Challenge for Pharmaceutical and Biomedical Applications

Chitosan—one of the natural multifunctional polymers—due to its unique and versatile biological properties is regarded as a useful compound in medical and pharmaceutical technology. Recently, considerable research effort has been made in order to develop safe and efficient chitosan products. However, the problem of poor stability of chitosan-based systems restricts its practical applicability; thus, it has become a great challenge to establish sufficient shelf-life for chitosan formulations. Improved stability can be assessed by controlling the environmental factors, manipulating processing conditions (e.g., temperature), introducing a proper stabilizing compound, developing chitosan blends with another polymer, or modifying the chitosan structure using chemical or ionic agents. This review covers the influence of internal, environmental, and processing factors on the long-term stability of chitosan products. The aim of this paper is also to highlight the latest developments which enable the physicochemical properties of chitosan-based applications to be preserved upon storage.

Apoptosis-mediated cytotoxicity of ouabain, digoxin and proscillaridin A in the estrogen independent MDA-MB-231 breast cancer cells

We examined the effects of three cardiac glycosides, ouabain, digoxin and proscillaridin A, on the proliferation of estrogen independent MDA-MB-231 breast cancer cells. In terms of reduction in cell viability, the compounds rank for both 24 h and 48 h of incubation in MDA-MB-231 cells in the order proscillaridin A > digoxin > ouabain. Digoxin for 24 h and 48 h of incubation in MDA-MB-231 cells proved to be only slightly more potent than ouabain, with IC50 values of 122 ± 2 and 70 ± 2 nM, respectively, compared to 150 ± 2 and 90 ± 2 nM for ouabain. In contrast, proscillaridin A, was much more active and showed a high level of cytotoxic potency, IC50 51 ± 2 and 15 ± 2 nM for 24 h and 48 h of incubation, respectively. The concentrations of digoxin, ouabain and proscillaridin A needed to inhibit [3H]thymidine incorporation into DNA by 50% (IC50) in MDA-MB-231 cells for 24 h of incubation were found to be 124 ± 2 nM, 142 ± 2 nM, and 48 ± 2 nM, respectively. In the present study, we demonstrated that ouabain, digoxin, and proscillaridin A induce apoptosis in MDA-MB-231 cells by increasing free calcium concentration and by activating caspase-3.

Dual effects of ouabain, digoxin and proscillaridin A on the regulation of apoptosis in human fibroblasts.

In this study, we looked at the effect of ouabain, digoxin and proscillaridin A on human fibroblasts. These data show that low concentrations of ouabain, digoxin and proscillaridin A can activate proliferation of human fibroblasts, suggesting that the Na+, K+-adenosine triphosphatase complex may act as a transducing receptor. It was shown that 30 nM ouabain, digoxin and proscillaridin A stimulated an antiapoptotic action by the increase in the level of phosphorylated extracellular signal-regulated kinases (P-ERK 1/2). Ouabain, digoxin and proscillaridin A only at the relatively high concentration of 300 nM increased intracellular Ca2+ concentration, activated caspase-3 and induced apoptosis in human fibroblasts. In terms of reduction in cell viability, antiproliferative and apoptotic activity, these cardiac glycosides rank in the order proscillaridin A >digoxin >ouabain.

The Effect of PAMAM Dendrimers on the Antibacterial Activity of Antibiotics with Different Water Solubility

Erythromycin (EM) and tobramycin (TOB) are well-known and widely used antibiotics, belonging to different therapeutic groups: macrolide and aminoglycoside, respectively. Moreover, they possess different solubility: EM is slightly soluble and TOB is freely soluble in water. It was previously demonstrated that PAMAM dendrimers enhanced the pharmacological activity of antifungal drugs by increasing their solubility. Therefore, it appears interesting to investigate the effect of PAMAM-NH2 and PAMAM-OH dendrimers generation 2 (G2) and generation 3 (G3) on the antibacterial activity of antibiotics with different water solubility. In this study it was shown that the aqueous solubility of EM was significantly increased by PAMAM dendrimers (PAMAM-NH2 and PAMAM-OH caused about 8- and 7- fold solubility increases, respectively). However, it was indicated that despite the increase in the solubility, there was only slight influence on the antibacterial activity of EM (2- and 4- fold decreases in the MBC values of EM in the presence of PAMAM-OH G3 and PAMAM-NH2 G2 or G3 for strains of Staphylococcus aureus were noted, respectively). It was also found that there was no influence of PAMAM on the antibacterial activity of hydrophilic TOB.

Hydrogel of Ketoconazole and PAMAM Dendrimers: Formulation and Antifungal Activity

Ketoconazole (KET), an imidazole derivative with well-known antifungal properties, is lipophilic and practically insoluble in water, therefore its clinical use has some practical disadvantages. The aim of the present study was to investigate the influence of PAMAM-NH2 and PAMAM-OH dendrimers generation 2 and generation 3 on the solubility and antifungal activity of KET and to design and evaluate KET hydrogel with PAMAM dendrimers. It was shown that the surface charge of PAMAM dendrimers strongly affects their influence on the improvement of solubility and antifungal activity of KET. The MIC and MFC values obtained by broth dilution method indicate that PAMAM-NH2 dendrimers significantly (up to 16-fold) increased the antifungal activity of KET against Candida strains (e.g., in culture Candida albicans 1103059/11 MIC value was 0.008 μg/mL and 0.064 μg/mL, and MFC was 2 μg/mL and 32 μg/mL for KET in 10 mg/mL solution of PAMAM-NH2 G2 and pure KET, respectively). Antifungal activity of designed KET hydrogel with PAMAM-NH2 dendrimers measured by the plate diffusion method was definitely higher than pure KET hydrogel and than commercial available product. It was shown that the improvement of solubility and in the consequence the higher KET release from hydrogels seems to be a very significant factor affecting antifungal activity of KET in hydrogels containing PAMAM dendrimers.

Alginate: Current Use and Future Perspectives in Pharmaceutical and Biomedical Applications

Over the last decades, alginates, natural multifunctional polymers, have increasingly drawn attention as attractive compounds in the biomedical and pharmaceutical fields due to their unique physicochemical properties and versatile biological activities. The focus of the paper is to describe biological and pharmacological activity of alginates and to discuss the present use and future possibilities of alginates as a tool in drug formulation. The recent technological advancements with using alginates, issues related to alginates suitability as matrix for three-dimensional tissue cultures, adjuvants of antibiotics, and antiviral agents in cell transplantation in diabetes or neurodegenerative diseases treatment, and an update on the antimicrobial and antiviral therapy of the alginate based drugs are also highlighted.

Synthesis and cytotoxic activity of G3 PAMAM-NH2 dendrimer-modified digoxin and proscillaridin A conjugates in breast cancer cells

Abstract The objective of this study was to determine the cytotoxicity, antiproliferative activity, and apoptosis induction activity of two modified glycosides – digoxin and proscillaridin A – conjugated to a generation 3 polyamidoamine dendrimer (G3 PAMAM-NH 2 ) in hu-man breast cancer cells. The results suggest that conjugation with the G3 PAMAM-NH 2 dendrimer enhances the cytotoxicity of modified digoxin and proscillaridin A both in MCF-7 and in MDA-MB-231 breast cancer cells. Additionally, the conjugate-induced apoptosis was significantly greater than apoptosis evoked by free modified digoxin and proscillaridin A.

Development and Evaluation of Liquid and Solid Self-Emulsifying Drug Delivery Systems for Atorvastatin

The objective of this work was to design and characterize liquid and solid self-emulsifying drug delivery systems (SEDDS) for poorly soluble atorvastatin. To optimize the composition of liquid atorvastatin-SEDDS, solubility tests, pseudoternary phase diagrams, emulsification studies and other in vitro examinations (thermodynamic stability, droplet size and zeta potential analysis) were performed. Due to the disadvantages of liquid SEDDS (few choices for dosage forms, low stability and portability during the manufacturing process), attempts were also made to obtain solid SEDDS. Solid SEDDS were successfully obtained using the spray drying technique from two optimized liquid formulations, CF3 and OF2. Despite liquid SEDDS formulation, CF3 was characterized by lower turbidity, higher percentage transmittance and better self-emulsifying properties, and based on the in vitro dissolution study it can be concluded that better solubilization properties were exhibited by solid formulation OF2. Overall, the studies demonstrated the possibility of formulating liquid and solid SEEDS as promising carriers of atorvastatin. SEDDS, with their unique solubilization properties, provide the opportunity to deliver lipophilic drugs to the gastrointestinal tract in a solubilized state, avoiding dissolution—a restricting factor in absorption rate of BCS Class 2 drugs, including atorvastatin.

Influence of unmodified and β-glycerophosphate cross-linked chitosan on anti-Candida activity of clotrimazole in semi-solid delivery systems.

The combination of an antifungal agent and drug carrier with adjunctive antimicrobial properties represents novel strategy of complex therapy in pharmaceutical technology. The goal of this study was to investigate the unmodified and ion cross-linked chitosan’s influence on anti-Candida activity of clotrimazole used as a model drug in hydrogels. It was particularly crucial to explore whether the chitosans’ structure modification by β-glycerophosphate altered its antifungal properties. Antifungal studies (performed by plate diffusion method according to CLSI reference protocol) revealed that hydrogels obtained with chitosan/β-glycerophosphate displayed lower anti-Candida effect, probably as a result of weakened polycationic properties of chitosan in the presence of ion cross-linker. Designed chitosan hydrogels with clotrimazole were found to be more efficient against tested Candida strains and showed more favorable drug release profile compared to commercially available product. These observations indicate that novel chitosan formulations may be considered as promising semi-solid delivery system of clotrimazole.

Application of standard cell cultures and 3D in vitro tissue models as an effective tool in drug design and development

Cell culture systems are essential tools used in a wide range of biomedical and clinical studies. Two dimensional cell culture models (2D) provide basic information on cytotoxicity, penetration and accumulation of drugs in cells and they are of outmost importance when selecting new compounds of the desired biopharmaceutical properties as candidates for novel drugs. The improvement over 2D growing cells are three dimensional (3D) tissue models that mimic in vivo conditions and the functions of living tissue more accurately. These models reduce the cost of drug development, enable more efficient drug screening, minimise failure rate in medicine discovery and eliminate animal use during experiments. The article provides an overview of 2D cell cultures and 3D tissue models - their properties, basic procedures, conditions of culturing and applications.