Galya Ivanova

Poly(butylcyanoacrylate) nanoparticles for topical delivery of 5-fluorouracil

Poly(butylcyanoacrylate) nanoparticles (PBCN) as a drug carrier of 5-fluorouracil (5FU) intended for topical treatment of skin lesia were investigated. The presence of 5FU (as saline solution, pH 10-11) in the polymerization medium affected the polymerization as well as the nanoparticle formation by influencing the initiation of the polymerization reaction. 5FU acted as an initiator in the anionic polymerization of n-butylcyanoacrylate monomer through its nucleophilic nitrogen centers. The results obtained by GPC, 1H NMR, and X-ray diffraction allude to a possible mechanism of cytostatic immobilization in the polymer matrix, with evidence for both free and bound forms of the drug.

Physicochemical characterization and in vitro behavior of daunorubicin-loaded poly(butylcyanoacrylate) nanoparticles.

The design, preparation and characterization of poly(butylcyanoacrylate) nanoparticles as a drug-delivery system for daunorubicin is reported. A range of light scattering [photon correlation spectroscopy (PCS)], spectroscopic [(1)H nuclear magnetic resonance ((1)H NMR), Fourier transform infrared (FTIR), chromatographic [gel permeation chromatography (GPC)] and quantum chemical techniques have been employed for the physicochemical characterization of drug-loaded nanoparticles and to clarify the mechanisms of drug immobilization in the polymer matrix. The presence of daunorubicin in the polymerization medium was found to affect both the degree of polymerization and the compactness of the resulting nanoparticles. The GPC, FTIR and (1)H NMR results confirmed cytostatic immobilization in the polymer matrix, with evidence for the presence of three types of inclusion: physically entrapped, polymer-associated (due to hydrogen bonds and/or dipole-charge interactions with the polymer chains), and polymer surface-adsorbed daunorubicin. The developed colloidal delivery system has the capacity for sustained in vitro release of daunorubicin. Preliminary in vitro assays were carried out on two cell lines, DLKP and DLKP-A, which display different levels of drug resistance, to evaluate the cytotoxicity of the drug-loaded nanoparticles.

Poly(amidoamine) dendrimer peripherally modified with 4-N,N-dimethylaminoethyleneamino-1,8-naphthalimide as a sensor of metal cations and protons.

A new poly(amidoamine) dendrimer from second generation whose periphery comprises sixteen fluorescent 4-N,N-dimethylaminoethylamino-1,8-naphthalimide units has been synthesized and characterized. In DMF, the dendrimer shows sensitivity to the presence of Cu(2+), Fe(3+) and protons. The changes in the fluorescence intensity of the material are in opposite directions if acids or metals are present. Fluorescence enhancements (FE from 5 to 9 depending on solvent) are recorded when the photoinduced electron transfer (PET) originating from the donating amine to the electron accepting naphthalimide is inhibited by the protonation of the N,N-dimethylamino groups. In the case of Cu(2+) cations, a fluorescence quenching (FQ of 6) is first observed, followed by fluorescence partial restoration. In the Fe(3+) case, the same behaviour is observed with a final FE of 2. The successive complexations of these cations by the dendrimer core and by the external rim of the dendrimer may explain the results.

Photophysical and photochemical properties of some 3-bromo-4-alkylamino-N-alkyl-1,8-naphthalimides

Photophysical properties of some 4-alkylamino-N-alkyl-1,8-naphthalimides and 3-bromo-4-alkylamino-N-alkyl-1,8-naphthalimides in ethanol solution have been investigated. It was demonstrated that the bromine atom in a C-3 position alters their properties. The bromine derivatives have a lower quantum yield of fluorescence owing to the influence of the bromine atom on the polarization of naphthalimide chromophoric system. On the other case, the photodegradation of these derivatives is higher and the reaction of photodegradation follows a pseudo first order.

Tautomeric Equilibria of 5-Fluorouracil Anionic Species in Water

It has long been postulated that rare tautomeric or ionized forms of nucleic acid bases may play a role in mispair formation. Therefore, ab initio quantum chemical investigations on the tautomeric equilibrium in 5-fluorouracil (5FU) and its anions (deprotonated from N1, AN1, and from N3, AN3) and their tautomeric forms in water were performed. The effect of the water as solvent was introduced using solute-solvent clusters (four water molecules). The influence of the water molecules on the tautomeric reactions between different forms was considered by multiple proton transfer mechanisms. We show that when a water dimer is located in the reaction site between the two pairs of N-H and C═O groups, the assistive effect of the water molecules is strengthened. All calculations of the solute-water complexes were carried out at an MP2 level of theory and supplemented with correction for higher order correlation terms at CCSD(T) level, using the 6-31+G(d,p) basis set. The ab initio calculated frequencies and Raman intensities of 5FU and its anions AN1, AN3, and dianion are in good agreement with the experimental Raman frequencies in aqueous solution at different pH. In order to establish the pH-induced structural transformation in the molecule of 5FU, further (1)H, (19)F, and (13)C NMR spectra in water solution for pH = 6.9-13.8 were acquired and the chemical shift alterations were determined as a function of pH. On the basis of NMR spectroscopic data obtained for 5FU in aqueous solution at alkaline pH, we suggest the existence of a mixture of the anionic tautomeric forms predicted by our theoretical calculations.

Excited state intramolecular proton transfer in 2-acetylindan-1,3-dione

Abstract Results on the absorption and luminescence properties of 2-acetylindan-1,3-dione in different solvents are reported. Evidence suggesting intramolecular proton transfer in the excited singlet state is presented. All possible tautomeric forms are studied by means of the AM1 method in both the ground and the first excited singlet state. On the basis of the results obtained the tautomers involved in the photocycle are proposed.

Structural characterization of inclusion complexes between cyanidin-3-O-glucoside and β-cyclodextrin.

Inclusion complex formation between the multiple equilibrium forms of cyanidin-3-O-glucoside (cy3glc) and β-cyclodextrin (β-CD) was investigated using a combined approach of NMR spectroscopy and Molecular Dynamics simulation. Diffusion ordered NMR spectroscopy (DOSY) and study of nuclear Overhauser effects (NOE) were used to determine the selective intermolecular interactions and structure of these complexes in aqueous solution. The observed chemical shift displacements of resonance signals of protons from the interior of β-CD cavity and protons belonging to the hemiketal (B) and cis-chalcone forms (Cc), the diffusion measurements using DOSY and the NOE studies have anticipated the formation of an inclusion complex between these two forms and β-CD. The analysis of the NMR spectral data has shown no evidence of internal interaction between β-CD and the flavylium cation (AH(+)) or trans-chalcone (Ct) forms of cy3glc. The hemiketal formed a 1:1 inclusion complex with β-cyclodextrin in which the pyranic C ring is deeply included inside the β-CD cavity while B ring lies on the plane of the wider rim of β-CD. The structure of the complexes was also clarified through a theoretical approach by Molecular Dynamics simulation.

MSCs CONDITIONED MEDIA AND UMBILICAL CORD BLOOD PLASMA METABOLOMICS AND COMPOSITION

Human mesenchymal stem cells (hMSCs) from umbilical cord (UC) blood (UCB) and matrix are tested clinically for a variety of pathologies but in vitro expansion using culture media containing fetal bovine serum (FBS) is essential to achieve appropriate cell numbers for clinical use. Human UCB plasma (hUCBP) can be used as a supplement for hMSCs culture, since UCB is rich in soluble growth factors and due to worldwide increased number of cryopreserved UCB units in public and private banks, without the disadvantages listed for FBS. On the other hand, the culture media enriched in growth factors produced by these hMSCs in expansion (Conditioned medium - CM) can be an alternative to hMSCs application. The CM of the hMSCs from the UC might be a better therapeutic option compared to cell transplantation, as it can benefit from the local tissue response to the secreted molecules without the difficulties and complications associated to the engraftment of the allo- or xeno-transplanted cells. These facts drove us to know the detailed composition of the hUCBP and CM, by 1H-NMR and Multiplexing LASER Bead Technology. hUCBP is an adequate alternative for the FBS and the CM and hUCBP are important sources of growth factors, which can be used in MSCs-based therapies. Some of the major proliferative, chemotactic and immunomodulatory soluble factors (TGF-β, G-CSF, GM-CSF, MCP-1, IL-6, IL-8) were detected in high concentrations in CM and even higher in hUCBP. The results from 1H-NMR spectroscopic analysis of CM endorsed a better understanding of hMSCs metabolism during in vitro culture, and the relative composition of several metabolites present in CM and hUCBP was obtained. The data reinforces the potential use of hUCBP and CM in tissue regeneration and focus the possible use of hUCBP as a substitute for the FBS used in hMSCs in vitro culture.

Anti-tyrosinase, antioxidant and antimicrobial activities of hydroxycinnamoylamides

Synthetic hydroxycinnamoylamides of amino acids (precursors of aromatic amines) were studied for their antioxidant activity in vitro by two antioxidant assay systems, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and inhibition of lipid peroxidation (LPO). Furthermore, these compounds were tested and compared with their corresponding cinnamoylamides of aromatic amines for their inhibitory activity using mushroom tyrosinase. In addition, five hydroxycinnamoyl amino acid amides were investigated for their antimicrobial effect. Structure–activity relationships analysis disclosed that the presence of catechol rest at amino acid or at benzene moieties of substituted cinnamic acid amides significantly scavenged DPPH radical and inhibited LPO. The results obtained by LPO clearly expressed the positive influence of indole moiety on the activity. Moreover, the existence of p-hydroxy substituted cinnamic acid moiety leads to better tyrosinase inhibition. Amongst the tested compounds, amides of p-coumaroyldopamine or tyramine and their corresponding amino acid precursors are the most potent tyrosinase inhibitors.

Artificial Neural Networks for Classification in Metabolomic Studies of Whole Cells Using 1H Nuclear Magnetic Resonance

We report the successful classification, by artificial neural networks (ANNs), of 1H NMR spectroscopic data recorded on whole-cell culture samples of four different lung carcinoma cell lines, which display different drug resistance patterns. The robustness of the approach was demonstrated by its ability to classify the cell line correctly in 100% of cases, despite the demonstrated presence of operator-induced sources of variation, and irrespective of which spectra are used for training and for validation. The study demonstrates the potential of ANN for lung carcinoma classification in realistic situations.