Antiproliferative and Cytotoxic Properties of Propynoyl Betulin Derivatives against Human Ovarian Cancer Cells: In Vitro Studies.

Due to the incidence of ovarian cancer (OC) and the limitations of available therapeutic strategies, it is necessary to search for novel therapeutic solutions. The aim of this study was to evaluate the cytotoxic effect of betulin 1 and its propynoyl derivatives 2-6 against ovarian cancer cells (SK-OV-3, OVCAR-3) and normal myofibroblasts (18Co). Paclitaxel was used as the reference compound. The propynoyl derivatives 2-6 exhibited stronger antiproliferative and cytotoxic activities compared to betulin 1. In both ovarian cancer cell lines, the most potent compound was 28-propynoylbetulin 2. In the case of compound 2, the calculated IC50 values were 0.2 µM for the SK-OV-3 cells and 0.19 µM for the OVCAR-3 cells. Under the same culture conditions, the calculated IC50 values for compound 6 were 0.26 µM and 0.59 µM, respectively. It was observed that cells treated with compounds 2 and 6 caused a decrease in the potential of the mitochondrial membrane and a significant change in cell morphology. Betulin 1, a diol from the group of pentacyclic triterpenes, has a confirmed wide spectrum of biological effects, including a significant anticancer effect. It is characterized by low bioavailability, which can be improved by introducing changes to its structure. The results showed that chemical modifications of betulin 1 only at position C-28 with the propynoyl group (compound 2) and additionally at position C-3 with the phosphate group (compound 3) or at C-29 with the phosphonate group (compound 6) allowed us to obtain compounds with greater cytotoxic activity than their parent compounds, which could be used to develop novel therapeutic systems effective in the treatment of ovarian cancer.

Bioresorbable Nonwoven Patches as Taxane Delivery Systems for Prostate Cancer Treatment.

Prostate cancer is the second most common cancer in males. In the case of locally advanced prostate cancer radical prostatectomy is one of the first-line therapy. However, recurrence after resection of the tumor can appear. Drug-eluting bioresorbable implants acting locally in the area of the tumor or the resection margins, that reduce the risk of recurrence would be advantageous. Electrospinning offers many benefits in terms of local delivery so fiber-forming polyesters and polyestercarbonates which are suitable to be drug-loaded were used in the study to obtain CTX or DTX-loaded electrospun patches for local delivery. After a fast verification step, patches based on the blend of poly(glycolide-ε-caprolactone) and poly(lactide-glycolide) as well as patches obtained with poly(lactide-glycolide- ε-caprolactone) were chosen for long-term study. After three months, 60% of the drug was released from (PGCL/PLGA) + CTX and it was selected for final, anticancer activity analysis with the use of PC-3 and DU145 cells to establish its therapeutic potential. CTX-loaded patches reduced cell growth to 53% and 31% respectively, as compared to drug-free patches. Extracts from drug-free patches showed excellent biocompatibility with the PC-3 cell line. Cabazitaxel-loaded bioresorbable patches are a promising drug delivery system for prostate cancer therapy.

Synthesis of the Bacteriostatic Poly(l-Lactide) by Using Zinc (II)[(acac)(L)H2O] (L = Aminoacid-Based Chelate Ligands) as an Effective ROP Initiator.

The paper presents a synthesis of poly(l-lactide) with bacteriostatic properties. This polymer was obtained by ring-opening polymerization of the lactide initiated by selected low-toxic zinc complexes, Zn[(acac)(L)H2O], where L represents N-(pyridin-4-ylmethylene) tryptophan or N-(2-pyridin-4-ylethylidene) phenylalanine. These complexes were obtained by reaction of Zn[(acac)2 H2O] and Schiff bases, the products of the condensation of amino acids and 4-pyridinecarboxaldehyde. The composition, structure, and geometry of the synthesized complexes were determined by NMR and FTIR spectroscopy, elemental analysis, and molecular modeling. Both complexes showed the geometry of a distorted trigonal bipyramid. The antibacterial and antifungal activities of both complexes were found to be much stronger than those of the primary Schiff bases. The present study showed a higher efficiency of polymerization when initiated by the obtained zinc complexes than when initiated by the zinc(II) acetylacetonate complex. The synthesized polylactide showed antibacterial properties, especially the product obtained by polymerization initiated by a zinc(II) complex with a ligand based on l-phenylalanine. The polylactide showed a particularly strong antimicrobial effect against Pseudomonas aeruginosa, Staphylococcus aureus, and Aspergillus brasiliensis. At the same time, this polymer does not exhibit fibroblast cytotoxicity.

Anticancer Activity of the Acetylenic Derivative of Betulin Phosphate Involves Induction of Necrotic-Like Death in Breast Cancer Cells In Vitro.

Betulin (BT) is a natural pentacyclic lupane-type triterpene exhibiting anticancer activity. Betulin derivatives bearing propynoyloxy and phosphate groups were prepared in an effort to improve the availability and efficacy of the drug. In this study, a comparative assessment of the in vitro anticancer activity of betulin and its four derivatives was carried out using two human breast cancer cell lines: SK-BR-3 and MCF-7. In both studied cell lines, 30-diethoxyphosphoryl-28-propynoylbetulin (compound 4) turned out to be the most powerful inhibitor of growth and inducer of cellular death. Detailed examination of that derivative pertained to the mechanisms underlying its anticancer action. Treatment with compound 4 decreased DNA synthesis and up-regulated p21WAF1/Cip1 mRNA and protein levels in both cell lines. On the other hand, that derivative caused a significant increase in cell death, as evidenced by increased lactate dehydrogenase (LDH) release and ethidium homodimer uptake. Shortly after the compound addition, an increased generation of reactive oxygen species and loss of mitochondrial membrane potential were detected. The activation of caspase-3 and fragmentation of genomic DNA suggested an apoptotic type of cell death. However, analysis of cellular morphology did not reveal any nuclear features typical of apoptosis. Despite necrosis-like morphology, dead cells exhibited activation of the cascade of caspases. These observations have led to the conclusion that compound 4 pushed cells to undergo a form of necrotic-like regulated cell demise.

Biodegradable Electrospun Nonwovens Releasing Propolis as a Promising Dressing Material for Burn Wound Treatment.

The selection of dressing is crucial for the wound healing process. Traditional dressings protect against contamination and mechanical damage of an injured tissue. Alternatives for standard dressings are regenerating systems containing a polymer with an incorporated active compound. The aim of this research was to obtain a biodegradable wound dressing releasing propolis in a controlled manner throughout the healing process. Dressings were obtained by electrospinning a poly(lactide-co-glycolide) copolymer (PLGA) and propolis solution. The experiment consisted of in vitro drug release studies and in vivo macroscopic treatment evaluation. In in vitro studies released active compounds, the morphology of nonwovens, chemical composition changes of polymeric material during degradation process, weight loss and water absorption were determined. For in vivo research, four domestic pigs, were used. The 21-day experiment consisted of observation of healing third-degree burn wounds supplied with PLGA 85/15 nonwovens without active compound, with 5 wt % and 10 wt % of propolis, and wounds rinsed with NaCl. The in vitro experiment showed that controlling the molar ratio of lactidyl to glycolidyl units in the PLGA copolymer gives the opportunity to change the release profile of propolis from the nonwoven. The in vivo research showed that PLGA nonwovens with propolis may be a promising dressing material in the treatment of severe burn wounds.

Bioactive (Co)oligoesters as Potential Delivery Systems of p-Anisic Acid for Cosmetic Purposes.

This article reports the studies on bioactive (co)oligoesters towards their use as controlled delivery systems of p-anisic acid. The objects of the study were oligo[3-hydroxy-3-(4-methoxybenzoyloxymethyl)propionate], (p-AA-CH2-HP)n oligoester, and oligo[(3-hydroxy-3-(4-methoxybenzoyloxymethyl)propionate)-co-(3-hydroxybutyrate)] [(p-AA-CH2-HP)x-co-(HB)y (co)oligoesters containing p-anisic acid moiety (p-AA, as the bioactive end and side groups) connected to the polymer backbone through the susceptible to hydrolysis ester bonds. A thorough insight into the hydrolysis process of the bioactive (co)oligoesters studied has allowed us to determine the release profile of p-AA as well as to identify polymer carrier degradation products. The p-AA release profiles determined on the basis of high-performance liquid chromatography (HPLC) measurements showed that the release of the bioactive compound from the developed (co)oligoester systems was regular and no burst effect occurred. Biological studies demonstrated that studied (homo)- and (co)oligoesters were well tolerated by HaCaT cells because none of them showed notable cytotoxicity. They promoted keratinocyte growth at moderate concentrations. Bioactive (co)oligoesters containing p-anisic acid moiety had somewhat decreased cell proliferation at the highest concentration (100 µg/mL). The important practical inference of the current study is that the (co)oligoesters developed have a relatively large load of the biologically active substance (p-AA) per polymer macromolecule, which unlocks their potential application in the cosmetic industry.

Electrochemical and Biological Performance of Biodegradable Polymer Coatings on Ti6Al7Nb Alloy.

The inhibition of the corrosion of metal implants is still a challenge. This study aimed to increase the corrosion resistance of Ti6Al7Nb alloy implants through surface modification, including grinding, sandblasting, and anodic oxidation followed by the deposition of a polymer coating. The aim of the work was to determine the influence of biodegradable polymer coatings on the physico-chemical properties of a Ti6Al7Nb alloy used for short-term implants. Biodegradable coatings prepared from poly(glycolide-caprolactone) (P(GCap)), poly(glycolide ε-caprolactone-lactide) (P(GCapL)), and poly(lactide-glycolide) (PLGA) were applied in the studies. The dip-coating method with three cycles of dipping was applied. Corrosion resistance was assessed on the basis of potentiodynamic studies. The studies were carried out on samples after 30, 60, and 90 days of exposure to Ringer's solution. Surface topography, wettability, and cytotoxicity studies were also carried out. The degradation process of the base material was evaluated on the basis of the mass density of the metal ions released to the solution. The results indicated the influence of the coating type on corrosion resistance. In addition, a beneficial effect of the polymer coating on the reduction of the density of the released metal ions was found, as compared to the samples without polymer coatings. The obtained results provide basic knowledge for the development of polymer coatings enriched with an active substance. The presence of ciprofloxacin in the coating did not reduce the corrosion resistance of the metal substrate. Moreover, the cytotoxicity test using the extract dilution method demonstrated that the implants' coatings are promising for further in vitro and in vivo studies.

Bioresorbable hydrogels prepared by photo-initiated crosslinking of diacrylated PTMC-PEG-PTMC triblock copolymers as potential carrier of antitumor drugs.

PTMC-PEG-PTMC triblock copolymers were prepared by ring-opening polymerization of trimethylene carbonate (TMC) in the presence of dihydroxylated poly(ethylene glycol) (PEG) with Mn of 6000 and 10,000 as macro-initiator. The copolymers with different PTMC block Lengths and the two PEGs were end functionalized with acryloyl chloride. The resulting diacrylated PEG-PTMC-DA and PEG-DA were characterized by using NMR, GPC and DSC. The degree of substitution of end groups varied from 50.0 to 65.1%. Hydrogels were prepared by photo-crosslinking PEG-PTMC-DA and PEG-DA in aqueous solution using a water soluble photo-initiator under visible light irradiation. The effects of PTMC and PEG block lengths and degree of substitution on the swelling and weight loss of hydrogels were determined. Higher degree of substitution leads to higher crosslinking density, and thus to lower degree of swelling and weight loss. Similarly, higher PTMC block length also leads to lower degree of swelling and weight loss. Freeze dried hydrogels exhibit a highly porous structure with pore sizes from 20 to 100 µm. The biocompatibility of hydrogels was evaluated by MTT assay, hemolysis test, and dynamic clotting time measurements. Results show that the various hydrogels present outstanding cyto- and hemo-compatibility. Doxorubicin was taken as a model drug to evaluate the potential of PEG-PTMC-DA and PEG-DA hydrogels as drug carrier. An initial burst release was observed in all cases, followed by slower release up to more than 90%. The release rate is strongly dependent on the degree of swelling. The higher the degree of swelling, the faster the release rate. Finally, the effect of drug loaded hydrogels on SKBR-3 tumor cells was evaluated in comparison with free drug. Similar cyto-toxicity was obtained for drug loaded hydrogels and free drug at comparable drug concentrations. Therefore, injectable PEG-PTMC-DA hydrogels with outstanding biocompatibility and drug release properties could be most promising as bioresorbable carrier of hydrophilic drugs.

Self-assembled micelles prepared from bio-based hydroxypropyl methyl cellulose and polylactide amphiphilic block copolymers for anti-tumor drug release.

Fully bio-based amphiphilic diblock copolymers were synthesized from hydroxypropyl methyl cellulose (HPMC) and amino-terminated poly(l-lactide) (PLLA) or poly(l-lactide-co-dl-lactide) (PLA) by reductive amination. The resulting HPMC-PLLA and HPMC-PLA copolymers with various hydrophobic block lengths were characterized by NMR, DOSY-NMR and FT-IR. Micelles were obtained by self-assembly of copolymers in aqueous medium. The micelles are spherical in shape, and the micelle size ranges from 150 to 180 nm with narrow distribution. The critical micelle concentration decreases with increasing PLA block length. Paclitaxel was loaded in micelles. Enhanced drug loading is obtained with increase of PLA block length. A biphasic release profile is observed with a burst of 40% followed by slower release up to 80%. MTT assay indicates the good cytocompatibility of HPMC-PLA micelles. SRB assay shows a significant cytotoxicity of paclitaxel-loaded micelles against SK-BR-3cells. It is thus concluded that bio-based HPMC-PLA block copolymers could be promising nano-carrier of anti-tumor drugs.

Bioresorbable filomicelles for targeted delivery of betulin derivative - In vitro study.

Filomicelles (worm-like micelles) possess high drug loading capacity and long circulation time in the bloodstream. A novel approach can be filomicelles with folic acid (FA) as a targeting moiety. Folate-drug delivery systems can target FA receptors (FAR) that are overexpressed in several human carcinomas, which can potentially maximize therapeutic efficacy while minimizing side effects. The aim of this study was to develop filomicelles from combination of poly(L-lactide)-Jeffamine-folic acid and poly(L-lactide)-poly(ethylene glycol) for delivery of betulin derivative. Phosphate derivative of betulin reveals high cytotoxicity against cancer cells, however its application is restricted due to poor solubility in water. Incorporation into hydrophobic core of micelles can effectively solubilize the drug. Three kinds of micelles were obtained with high drug loading capacity. Based on TEM analysis, the copolymers formed exclusively filomicelles or mixture of filomicelles and spherical micelles. All kinds of micelles provided release of betulin derivative for over 9 days and apart the very initial phase displayed similar release profile. The influence of PLA block on initial burst effect was revealed. The in vitro cytotoxicity of betulin derivative loaded micelles against FAR-positive HeLa cells was confirmed, which proves their usefulness for targeted delivery of cytostatic drug.

The Synthesis and Structural Characterization of Graft Copolymers Composed of γ-PGA Backbone and Oligoesters Pendant Chains.

The novel copolymers composed of poly-γ-glutamic acid (γ-PGA) and oligoesters have been developed. The structures of the obtained copolymers including variety of end groups were determined at the molecular level with the aid of electrospray ionization multistage mass spectrometry (ESI-MSn). The fragmentation experiment performed for the selected sodium adducts of the copolymers confirmed that the developed methods lead to the formation of graft copolymers composed of poly-γ-glutamic acid (γ-PGA) backbone and oligoesters pendant chains. Moreover, it was established that fragmentation of selected sodium adducts of graft copolymers proceeded via random breakage of amide bonds along the backbone and ester bonds of the oligoesters pendant chains. Considering potential applications of the synthesized copolymers in the area of biomaterials, the hydrolytic degradation under laboratory conditions and in vitro cytotoxicity tests were performed. The ESI-MSn technique applied in this study has been proven to be a useful tool in structural studies of novel graft copolymers as well as their degradation products. Graphical Abstract ᅟ.

Effect of polymer degradation on prolonged release of paclitaxel from filomicelles of polylactide/poly(ethylene glycol) block copolymers.

Paclitaxel is one of the most efficient anticancer agents, but the conventional dosage formulations cause many side effects. PLA-PEG filomicelles are promising carriers of paclitaxel because high loading capacity and long term release can be achieved. Slow release of cytostatic drugs is very advantageous due to prolonged exposure of tumor cells to cytostatic over multiple cell cycles. The aim of this study was to evaluate the potential of bioresorbable PLA-PEG filomicelles for prolonged delivery of paclitaxel. Paclitaxel is encapsulated in PLLA-PEG filomicelles and PDLLA-PEG spherical micelles. Drug release was studied in PBS at 37°C at various pH values to elucidate the influence of polymer degradation on drug release. NMR, GPC and HPLC were used to follow polymer degradation and drug release. The release of paclitaxel is strongly dependent on the degradation of micelles. A biphasic drug release profile is observed for both PLLA-PEG and PDLLA-PEG micelles: slow release in the first phase and faster release in the second phase. Degradation is faster at acidic pH than at pH7.4, and PLLA-PEG filomicelles degrade less rapidly than PDLLA-PEG spherical micelles, leading to various rates of drug release. The correlation between degradation and drug release is very helpful for the development of novel drug carriers with tailored properties. Importantly, the cytotoxic activity of PLLA-PEG filomicelles was evidenced, thus showing their potential as carrier of antitumor drugs.

Multidrug PLA-PEG filomicelles for concurrent delivery of anticancer drugs-The influence of drug-drug and drug-polymer interactions on drug loading and release properties.

This study aimed to analyze the influence of drug-drug and drug-polymer interactions on drug loading and release properties of multidrug micelles. Three hydrophobic drugs-paclitaxel (Ptx), 17-AAG and rapamycin (Rap) were incorporated in poly(l-lactide)-poly(ethylene glycol) (PLA-PEG) filomicelles. Double loaded micelles containing Ptx and 17-AAG were used for the sake of comparison. (1)H NMR confirmed the effective incorporation of the various drugs in micelles, and HPLC allowed to determine the drug loading contents. FTIR was used to evaluate interactions between particular drugs and between drugs and copolymer. Ptx and 17-AAG present similar loading efficiencies in double loaded micelles probably due to interactions of drugs with each other and also with the copolymer. In contrast, unequal drug loading properties are observed for triple loaded micelles. Rapamycin shows very weak interactions with the copolymer, and displays the lowest loading efficiency. In vitro release of drugs from micelles was realized in pH 7.4 phosphate buffered saline at 37°C, and monitored by HPLC. Similar release profiles are observed for the three drugs: a strong burst followed by slower release. Nevertheless, Ptx release from micelles is significantly slower as compared to 17-AAG and Rap, probably due to interactions of NH and OH groups of Ptx with the carbonyl group of PLA. In vitro cytotoxicity of Ptx/17-AAG/Rap loaded micelles and a mixture of free drugs was determined. Drug loaded micelles exhibit advantageous effect of prolonged drug release and cytotoxic activity against Caco-2 cells, which makes them a promising solution for simultaneous drug delivery to solid tumors. Therefore, understanding of interactions within multidrug micelles should be a valuable approach for the development of concurrent delivery systems of anticancer drugs with tailored properties.

Influence of 28-O-propynoylbetulin on proliferation and apoptosis of melanotic and amelanotic human melanoma cells.

INTRODUCTION: A relatively new approach in treatment of malignant melanoma is the use of betulin and its synthetic derivatives that have anticancer properties. The aim of the study was to determine the effect of an acetylenic derivative of betulin, 28-O-propynoylbetulin, on cell growth and apoptosis induction in human melanotic and amelanotic melanoma cells. MATERIALS AND METHODS: The A2058 and C32 cell lines were incubated with 28-O-propynoylbetulin (working solutions from 0.1 to 10 µg/ml). To evaluate cell proliferation, a sulforhodamine B based assay was conducted. In order to elucidate the early stages of apoptosis in both melanoma cell lines, caspase-3 activity was evaluated. RESULTS: The administration of 28-O-propynoylbetulin at a concentration equal to or less than 1 µg/ml did not cause a statistically significant change in the cell proliferation in either melanoma cell line (compared to control, p>0.05). Higher concentrations of the compound (3 and 10 µg/ml) inhibited the cell growth (in comparison to control, p<0.05). These results corresponded with caspase-3 activity results that revealed an increase of enzyme activity after 24-hour incubation with 3 and 10 µg/ml of the compound (compared to control, p<0.05). DISCUSSION: The study revealed that 28-O-propynoylbetulin may have diverse effects on melanoma cells and could be a strong inhibitor of cell growth (C32 cells) or exert a more potent proapoptotic effect (A2058 cells). These findings support the possibility of the use of EB5 in different antimelanoma approaches.

ANTIPROLIFERATIVE ACTIVITY OF NOVEL ACETYLENIC DERIVATIVES OF BETULIN AGAINST G-361 HUMAN MELANOMA CELLS.

Acetylenic derivatives of betulin were tested in vitro for their antiproliferative activity against G-361 human melanoma cells. Two types of betulin derivatives were studied: monoesters, obtained by modification of the hydroxyl group at C-28 position, and diesters modified at both C-28 and C-3 positions. To assess cell proliferation, a colorimetric sulforhodamine B based method was used. All the tested monoesters inhibited cellular growth and 28-O-propynoylbetulin showed the strongest cytotoxic effect. Esterification of the C-3 hydroxyl group of the molecule abolished its growth inhibitory activity.

Designing of Biodegradable and Biocompatible Release and Delivery Systems of Selected Antioxidants Used in Cosmetology.

Conjugates of antioxidants p-anisic (p-AA) and vanillic (VA) acids with nontoxic, biocompatible, and biodegradedable oligo-(R,S)-(3-hydoxybutyrate) carrier were synthesized, and their structural and biological characterization was performed. The molecular structure of the bioconjugates, in which antioxidants are covalently bonded with oligo(3-hydroxybutyrate) (OHB) chains, has been proven by mass spectrometry supported by NMR. The bioconjugate hydrolytic degradation studies allowed gaining thorough insight into the hydrolysis process and confirmed the release of p-AA and VA. In vitro studies demonstrated that all of the conjugates studied were well tolerated by KB and HaCaT cell lines, as they had no marked cytotoxicity, while conjugates with a relatively short OHB carrier are optimal to support keratinocyte function. The preliminary study of the biological activity confirmed the protective effect of VA-OHB conjugates against H2O2-induced lipid peroxidation in human keratinocytes (HaCaT). It was also demonstrated that the selected bioconjugates can penetrate all layers of the skin, which shows their functionality and opens up their potential application in cosmetology.

Scaffolds with shape memory behavior for the treatment of large bone defects.

The aim of the presented study was preparation, analysis of properties, and in vitro characterization of porous shape-memory scaffolds, designed for large bone defects treatment using minimally invasive surgery approach. Biodegradable terpolymers of l-lactide/glycolide/trimethylene carbonate (LA/GL/TMC) and l-lactide/glycolide/ε-caprolactone (LA/GL/Cap) were selected for formulation of these scaffolds. Basic parameters of shape memory behavior (i.e. recovery ratio, recovery time) and changes in morphology (SEM, average porosity) and properties (surface topography, water contact angle, compressive strength) during shape memory cycle were characterized. The scaffolds preserved good mechanical properties (compressive strength about 0.7 to 0.9 MPa) and high porosity (more than 80%) both in initial shape as well as after return from compressed shape. Then the scaffolds in temporary shape were inserted into the model defect of bone tissue at 37°C. After 12 min the defect was filled completely as a result of shape recovery process induced by body temperature. The scaffold obtained from LA/GL/TMC terpolymer was found the most prospective for the planned application thanks to its appropriate recovery time, high recovery ratio (more than 90%), and cytocompatibility in contact with human osteoblasts and chondrocytes.

Influence of betulin and 28-O-propynoylbetulin on proliferation and apoptosis of human melanoma cells (G-361).

INTRODUCTION: Pentacyclic triterpenes are a group of compounds known to have anticancer activity. One of the best characterized triterpenes is betulin, which can be isolated from bark of birch trees and modified into new compounds with various interesting medical properties. Betulin is involved in activation of the caspase cascade and promotes cell death. The aim of the study was to investigate the effect of betulin and its acetylenic derivative, 28-O-propynoylbetulin, on proliferation and apoptosis in a human melanoma cell line. MATERIALS AND METHODS: The G-361 melanoma cell line was used. To evaluate growth arrest and caspase-3 activity, cells were treated with betulin and its derivative at a wide range of concentrations from 0.1 to 10 µg/mL. RESULTS: Betulin and 28-O-propynoylbetulin inhibited cell proliferation in a concentration-dependent manner. The cell cycle analysis revealed an increase of the sub-G1 cell fraction (representing dead cells) after incubation of cells with betulin and 28-O-propynoylbetulin. The observed cytotoxic effects were more pronounced for 28-O-propynoylbetulin. Activity of caspase-3 in 28-O-propynoylbetulin treated cells was nearly 2-fold greater compared to cells incubated with betulin. DISCUSSION: Our results show that betulin and 28-O-propynoylbetulin were effective in inhibition of cell growth and induction of apoptosis in a human melanoma cell line. The addition of the propynoyl group at the C-28 hydroxyl group of betulin led to a greater proapoptotic and antiproliferative effect in comparison to unmodified betulin. These observations suggest that the obtained derivative is a potent anti-melanoma agent.

Effect of valproic acid on the proliferation and apoptosis of the human melanoma G-361 cell line.

Melanoma malignant is characterized by a high malignancy and low susceptibility to treatment. Due to these properties, there is a growing interest in compounds that would have the ability to inhibit proliferation, induce differentiation of tumor cells and initiate the apoptotic pathway. In vitro and in vivo research indicate that valproic acid (a histone deacetylase inhibitor) may have anti-cancer properties. In our study, the role of VPA on proliferation and apoptosis in G-361 human melanoma cell line was examined. Obtained results indicated that administration of VPA at concentrations above ≥ 1 mM led to significant inhibition of cell growth. Simultaneously, it was observed that VPA at higher concentrations (5 and 10 mM) caused an increase in caspase-3 activity.

The influence of chain microstructure of biodegradable copolyesters obtained with low-toxic zirconium initiator to in vitro biocompatibility.

Because of the wide use of biodegradable materials in tissue engineering, it is necessary to obtain biocompatible polymers with different mechanical and physical properties as well as degradation ratio. Novel co- and terpolymers of various composition and chain microstructure have been developed and applied for cell culture. The aim of this study was to evaluate the adhesion and proliferation of human chondrocytes to four biodegradable copolymers: lactide-coglycolide, lactide-co-ε-caprolactone, lactide-co-trimethylene carbonate, glycolide-co-ε-caprolactone, and one terpolymer glycolide-colactide-co-ε-caprolactone synthesized with the use of zirconium acetylacetonate as a nontoxic initiator. Chain microstructure of the copolymers was analyzed by means of ¹H and ¹³C NMR spectroscopy and surface properties by AFM technique. Cell adhesion and proliferation were determined by CyQUANT Cell Proliferation Assay Kit. After 4 h the chondrocyte adhesion on the surface of studied materials was comparable to standard TCPS. Cell proliferation occurred on all the substrates; however, among the studied polymers poly(L-lactide-coglycolide) 85 : 15 that characterized the most blocky structure best supported cell growth. Chondrocytes retained the cell membrane integrity evaluated by the LDH release assay. As can be summarized from the results of the study, all the studied polymers are well tolerated by the cells that make them appropriate for human chondrocytes growth.