Antioxidant and antityrosinase activity of aqueous extracts of green asparagus

The effect of aqueous extracts of green asparagus (AGA) on antioxidation and tyrosinase inhibition in acellular and cellular systems was investigated. The results showed that AGA inhibited tyrosinase with an IC50 value of 1.21 mg/ml in a mixed-type inhibition. In the range of 0.05-1 mg/ml, the inhibitory effect on tyrosinase activity in B16 cells increased with increasing concentration of AGA. Meanwhile, the levels of glutathione in B16 cells were elevated by AGA in comparison to the control. In addition, AGA, in the range of 0.1-0.5 mg/ml, also exhibited radical scavenging, chelating activities and protected liposome against oxidative damage. The high performance liquid chromatography analysis indicated that polyphenolic components such as rutin, quercetin, kaempferol, and isorhamnetin were present in the AGA. This study suggested that AGA could play an important role in the regulation of tyrosinase activity and seem to be a natural inhibitor of browning reaction. (C) 2010 Elsevier Ltd. All rights reserved.