RESUMO
The purpose of the study is to evaluate the relationship between the extraction parameters and the metal chelating activity of Centella asiatica (CA) and Erythroxylum cuneatum (EC). The response surface methodology was used to optimize the extraction parameters of methanolic extract of CA and EC with respect to the metal chelating activity. For CA, Run 17 gave optimum chelating activity with IC50 = 0.93 mg/mL at an extraction temperature of 25°C, speed of agitation at 200 rpm, ratio of plant material to solvent at 1 g : 45 mL and extraction time at 1.5 hour. As for EC, Run 13 with 60°C, 200 rpm, 1 g : 35 mL and 1 hour had metal chelating activity at IC50 = 0.3817 mg/mL. Both optimized extracts were further partitioned using a solvent system to evaluate the fraction responsible for the chelating activity of the plants. The hexane fraction of CA showed potential activity with chelating activity at IC50 = 0.090 and the ethyl acetate fraction of EC had IC50 = 0.120 mg/mL. The study showed that the response surface methodology helped to reduce the extraction time, temperature and agitation and subsequently improve the chelating activity of the plants in comparison to the conventional method.
RESUMO
Bioassay-guided fractionation of the methanolic extract of Tamarindus indica fruits led to the isolation of L-(-)-di-n-butyl malate which exhibited a pronounced cytotoxic activity against sea urchin embryo cells. In order to study structure-activity relationships, close-structure relatives of di-n-butyl malate were synthesized using D-(+)- and L-(-)-malic acid as starting materials, and their cytotoxic activities were examined for the sea urchin embryo assay. L-(-)-Di-n-pentyl malate was the most effective inhibitor to the development of the fertilized eggs. Significant inhibitory activity was not seen in the esters of D-(-)-isomer.
Assuntos
Anti-Infecciosos/isolamento & purificação , Citotoxinas/isolamento & purificação , Fabaceae , Malatos/isolamento & purificação , Plantas Medicinais , Animais , Antibacterianos , Anti-Infecciosos/síntese química , Anti-Infecciosos/toxicidade , Aspergillus/efeitos dos fármacos , Bacillus subtilis/efeitos dos fármacos , Blastocisto/efeitos dos fármacos , Cladosporium/efeitos dos fármacos , Citotoxinas/síntese química , Citotoxinas/toxicidade , Embrião não Mamífero/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Malatos/síntese química , Malatos/toxicidade , Testes de Sensibilidade Microbiana , Estrutura Molecular , Ouriços-do-Mar , Relação Estrutura-AtividadeRESUMO
An analysis of rotavirus electropherotypes circulating in Kuala Lumpur, Malaysia, over 7 years showed that all except 1 of the 360 electropherotypes encountered were characteristic of group A rotaviruses. The long electropherotype predominated annually, and there was a rarity of short electropherotypes. Extensive genome variability and cocirculation of different electropherotypes were observed annually. A sequential appearance of the predominant electropherotype was observed in all years of the study, except for 1985 and 1988, when one electropherotype predominated throughout the study periods. There was no shift in the predominant electropherotype over a 6-year period.
