Kifunensine is an alkaloid produced by the fungus, Kitasatosporia kifunense, and has been shown to be a weak inhibitor of aryl mannosidase. It is a unique oxamide derivative of mannojirimycin and a potent inhibitor of the glycoprotein processing enzyme mannosidase I. Kifunenesine is ineffective in inhibiting either mannosidase II or the endoplasmic reticulum (ER) a-mannosidase. It also possesses immunomodulating properties based on chemical, physicochemical and x-ray crystallographic analysis. When tested in cell culture using influenza virus-infected MDCK cells, kifunensine, at 1 mg/ml or less, caused almost complete inhibition of complex chain formation with the accumulation of Man9(GlcNAc)2. Thus, kifunensine was proven to be 50 to 100 times more effective than deoxymannojirimycin. Physicochemical characteristics: Kifunensine is soluble in hot water. Solutions should be made immediately prior to use. The compound should be dessicated and stored at -20 deg C.