Inhibition of -amylase and -glucosidase activities by ethanolic extract of Amaranthus cruentus leaf as affected by blanching

This study investigated the inhibitory effect of Amaranthus cruentus leaf on key enzyme linked to type-2 diabetes (α-amylase and α-glucosidase) as well as assessing the effect of blanching (a commonly practiced food processing technique) of the vegetable on these key enzymes. Fresh leaves of A. cruentus were blanched in hot water for 10 min, and the ethanolic extracts of both the fresh and blanched vegetables were prepared and used for subsequent analysis. The inhibitory effect of the extract on α-amylase and α-glucosidase activities as well as some antioxidant parameter was determined in vitro. The result revealed that extract of unprocessed A. cruentus leaf reduce Fe3+ to Fe2+ and also inhibited α-amylase and α-glucosidase activities in a dose dependent manner. However, blanching of the leafy vegetables caused a significant (P < 0.05) increase in the antioxidant properties but decreased their ability to inhibit α-amylase and α-glucosidase activities. This antioxidant properties and enzyme inhibition could be part of the mechanism by which they are used in the treatment/prevention of type-2 diabetes. However, the blanched vegetable reduced their ability to inhibit both α-amylase and α-glucosidase activity in vitro.   Key words: Amaranthus cruentus, blanching, antioxidants, α-amylase, α-glucosidase.