RESUMO
In our present study, the inhibitory effect of brazilein from Caesalpinia sappan on tyrosinase activity was investigated through multi-spectroscopic and molecular docking techniques. The result has shown that brazilein reversibly inhibited tyrosinase in a mixed type manner. The interaction of brazilein with the amino acid residues of tyrosinase has been validated through fluorescence quenching studies. Copper interaction studies suggested that brazilein could bind with copper ions of the enzyme. Circular dichroism analysis confirmed that brazilein induced secondary structural changes in tyrosinase. Docking studies further authenticate that brazilein forms hydrophobic and hydrogen bonding with the active site residues of tyrosinase. Moreover, in vitro studies confirmed that the inhibitory mechanism of cellular tyrosinase and melanin synthesis by brazilein in B16F0 melanoma cells. These results suggested that brazilein act as a potential tyrosinase inhibitor and it would contribute as a of novel tyrosinase inhibitor in food, cosmetic and pharmaceutical industry.
Assuntos
Benzopiranos/química , Benzopiranos/farmacologia , Indenos/química , Indenos/farmacologia , Melaninas/biossíntese , Monofenol Mono-Oxigenase/antagonistas & inibidores , Monofenol Mono-Oxigenase/química , Animais , Sobrevivência Celular/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , Simulação por Computador , Cobre/química , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Íons/química , Cinética , Melanoma Experimental , Camundongos , Conformação Molecular , Simulação de Acoplamento Molecular , Espectroscopia de Prótons por Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Nano-silver (Nano-Ag) particles were synthesized and then characterized using transmission electron microscopy (TEM) and X-ray diffractometry. TEM showed that Nano-Ag were spherical in shape and their size ranged from 40 to 60nm. X-ray diffractometry indicated that the sample was crystalline and had a face centered cubic structure of pure silver. Genotoxicity of this Nano-Ag was evaluated in human peripheral blood cells using the alkaline comet assay. Results indicated that Nano-Ag (50 and 100µg/mL) caused DNA damage following a 3h treatment. Subsequently, a short treatment of 5min also showed DNA damage. In conclusion, we have shown that the synthesized Nano-Ag induced DNA damage in human peripheral blood cells as detected by the alkaline comet assay. Results further indicated that treatment of cells with Nano-Ag in the presence of hydrogen peroxide did not induce any DNA damage.
