Biological activities of cyclophellitol.

Cyclophellitol [1S,2R,3S,4R,5R,6R)-5-hydroxymethyl-7-oxabicyclo[4,1,0] heptane-2,3,4-triol) was tested against 9 glycosidases and found to be a specific inhibitor of almond beta-glucosidase. Cyclophellitol inhibited almond beta-glucosidase activity by 50% at 0.8 micrograms/ml and was a competitive inhibitor of almond beta-glucosidase as revealed by Lineweaver-Burk plot. Cyclophellitol was inactive against yeast alpha-glucosidase, beta-galactosidase, beta-glucuronidase, alpha-L-fucosidase, end-beta-N-acetyl glucosaminidase, alpha-mannosidase, and cellulase. It was weakly active toward fungal beta-xylosidase. Cyclophellitol-treated almond beta-glucosidase was equally suppressed after dialysis; thus cyclophellitol is likely to bind to almond beta-glucosidase irreversibly. The inhibitor was found by fluorimetric assay to be active against beta-glucosidase but inactive toward alpha-glucosidase in Molt-4 microsomal fraction. It also inhibited Molt-4 beta-glucocerebrosidase completely at 2 micrograms/ml when the enzyme was assayed with a synthetic labeled substrate, and the inhibitory activity was more than one hundred times higher than that of nojirimycin, castanospermine, or of deoxynojirimycin. Mice administered 1 mg of cyclophellitol daily for 5 days began to exhibit severe abnormalities of nervous system similar to those found in Gaucher's mouse.