RESUMEN
The aim of our work was the synthesis and physicochemical characterization of a unique conjugate consisting of gold nanoparticles (AuNPs) and a pharmacologically active anticancer substance abiraterone (AB). The direct coupling of AB with gold constitutes an essential feature of the unique AuNPsâ»AB conjugate that creates a promising platform for applications in nanomedicine. In this work, we present a multidisciplinary, basic study of the obtained AuNPsâ»AB conjugate. Theoretical modeling based on the density functional theory (DFT) predicted that the Aun clusters would interact with abiraterone preferably at the N-side. A sharp, intense band at 1028 cm-1 was observed in the Raman spectra of the nanoparticles. The shift of this band in comparison to AB itself agrees well with the theoretical model. AB in the nanoparticles was identified by means of electrochemistry and NMR spectroscopy. The sizes of the Au crystallites measured by XRPD were about 9 and 17 nm for the nanoparticles obtained in pH 7.4 and 3.6, respectively. The size of the particles as measured by TEM was 24 and 30 nm for the nanoparticles obtained in pH 7.4 and pH 3.6, respectively. The DLS measurements revealed stable, negatively charged nanoparticles.
RESUMEN
Crystal and molecular structures of 2 conformational polymorphs (forms I and II) of olopatadine hydrochloride, an antiallergic agent, are presented. Both crystal modifications crystallize in the monoclinic crystal system with 1 olopatadine hydrochloride molecule in the Z configuration in the asymmetric unit. Molecules are arranged into the centrosymmetric association through the interactions of the intermolecular strong and weak hydrogen bonds of N-H Cl, O-H Cl and C-H Cl, C-H O types. Conformational change between polymorphs is proved by calculations of a maximum torsion angle deviation (max[Δθ]) and a root-mean-square deviation between the atomic positions (rmsd[r]). The physicochemical characterization of polymorphs is performed by X-ray powder diffraction, infrared and Raman spectroscopy, differential scanning calorimetry. The comparison of the melting points and heats of fusions shows that the forms are monotropically related.
Asunto(s)
Antialérgicos/química , Modelos Químicos , Clorhidrato de Olopatadina/química , Absorción Fisicoquímica , Cristalización , Estructura Molecular , Solubilidad , Solventes/química , Agua/químicaRESUMEN
In this article the crystal structures of the starting material TZ-5 and the key intermediate TZ-6 of temozolomide (TZ-7), an anticancer therapeutic agent, are presented, together with their spectroscopic and thermal characteristics. Both compounds crystallize in the triclinic P-1 space group. X-ray crystallography studies proved that the compound TZ-6 exists as a monohydrate. A complete structural assignment was obtained for the signals in the 1H-, 13C- and 15N-nuclear magnetic resonance spectra and the structures were confirmed by Fourier-Transform infrared and Raman spectroscopy. The article describes the importance of the high purity of TZ-6 during the small-scale plant production of TZ-7 in a desired polymorphic form III with the purity higher than 99.50%, according to an HPLC method.