– Australine is a pyrrolizidine alkaloid originally isolated fromC. australethat has enzyme inhibitory activities.1,2,3It is an inhibitor of glucoamylase (IC50= 5.8 μM) that also inhibits glucosidase I, sucrase, maltase, andA. nigerα-glucosidase (IC50s = 20, 28, 35, and 28 μM, respectively).2,3Australine is selective for these enzymes over glucosidase II, α- and β-mannosidase, and α- and β-galactosidase up to 500 μM, β-glucosidase, with only 5% inhibition at 66 μM, as well as isomaltase and trehalase (IC50= 97 and 160 μM, respectively). Australine (500 μg/ml) inhibits glycoprotein processing of viral glycoproteins in influenza virus-infected MDCK cells and induces the accumulation of glycoproteins.2