Inhibition of glycosidases by Astragalus lusitanicus and correlation with toxicity

This study determined whether Astragalus lusitanicus inhibits glycosidase enzymes other than alpha-mannosidase. Plasma collected from lambs given fresh A lusitanicus inhibited beta-glucosidase and beta-galactosidase, indicating the presence of inhibitors in their blood. The residual activity of these enzymes was also modified in tissues of dead animals. beta-glucosidase activity was reduced in liver and kidney specimens with pronounced effects in tissues of animal that presented with prominent clinical signs of poisoning; beta-galactosidase activity was decreased by 88.5 to 95% in kidney, while that of liver remained unchanged. Fractions of the plant butanol extract inhibited the gycosidase enzymes. Chemical analysis revealed the presence of hypaphorin in the extract of A lusitanicus. As a tryptophan derivative, this alkaloid may play a role in the toxicity of this legume.