RESUMO
New derivatives of steviol 1, the aglycone of the glycosides of Stevia rebaudiana, including a novel class of semisynthetic diterpenoids, namely macrocyclic ent-kauranes were synthesized. These compounds possess antituberculosis activity inhibiting the in vitro growth of Mycobacterium Tuberculosis (H37R(V) strain) with MIC 5-20 µg/ml that is close to MIC 1 µg/ml demonstrated by antituberculosis drug isoniazid in control experiment. For the first time it was found that the change of ent-kaurane geometry (as in steviol 1) of tetracyclic diterpenoid skeleton to ent-beyerane one (as in isosteviol 2) influences on antituberculosis activity.
Assuntos
Antituberculosos/síntese química , Diterpenos do Tipo Caurano/química , Compostos Macrocíclicos/química , Antituberculosos/química , Antituberculosos/farmacologia , Cristalografia por Raios X , Diterpenos do Tipo Caurano/síntese química , Diterpenos do Tipo Caurano/farmacologia , Testes de Sensibilidade Microbiana , Conformação Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Stevia/químicaRESUMO
Lyotropic metallomesogens containing trivalent rare-earth metal ions have unique attractive behavior due to the combination of some specific properties of the lanthanide ions with anisotropic supramolecular organization liquid crystal and provide new promises in biochemistry and materials science. In this article, we have studied the liquid crystal and luminescence properties of lyotropic systems containing Eu(III) and Tb(III) ions based on nonionic surfactants. The type, the structural parameters of the mesophases, and the structure of a liquid crystal complex have been investigated using polarized optical microscopy (POM), X-ray diffraction, and Fourier transform infrared. In addition, on the basis of the luminescence lifetime, the structure of the first coordination sphere was determined. The results obtained based on time-resolved spectroscopy data are discussed in the light of the influence ligand environment, ion type, and the type of supramolecular organization on the luminescence efficiency of lyotropic lanthanide containing systems. The first time was reported for Eu(III) complexes increasing the luminescence efficiency in the hexagonal phase compared to the lamellar mesophase.
