The carbohydrate-derived lactone phenylsemicarbazones 3 and 4 were prepared from 5 and 8 (Scheme). Treatment with 4-phenylsemicarbazide gave 6 and 7 (77:23) and 9 and 10 (76:24), respectively. Oxidation of 6 and 9 by Cr0,-pyridine to 11 and 13, followed by deprotection, yielded 3 and 4. The structure of 3 was established by X-ray analysis. Enzyme-inhibition studies using emulsin revealed that 3 is a competitive inhibitor with Ki = 23 pm. The activity of 4 was examined using N-acetylglucosaminidase from bovine kidney, Aspergillus niger, and Artemia salina. Compound 4 was found to be a competitive inhibitor of all three enzymes with Ki values of 0.13,6.0, and 0.71 pm and K M / K ~ values of 6910,45, and 465, respectively.
Introduction.
-In 1986, Beer and Vasella reported that the N-phenylcarbamate 1 is a strong P-glucosidase inhibitor [ 11. The 2-acetamido-2-deoxy analogue 2 [2] is avery potent N-acetylglucosaminidase inhibitor [3]. In both cases, the phenylcarbamates are much stronger inhibitors than the corresponding lactones or hydroximolactones, indicating an important role for the interaction of the C( 1) substituent with the enzyme. To learn more about the effects of the C( 1) substituents, we desired to prepare the semicarbazones 3 and 4, and to evaluate the inhibition of emulsin by 3 and of the N-acetylglucosaminidases from bovine kidney, Aspergillus niger, and from the brine shrimp Artemia salina by 4. We had demonstrated earlier that a protein preparation from Artemia salina contains Nacetylglucosaminidase activity which is susceptible to inhibition by 2-acetamido-2-deoxy-D-glucono-1,5-lactone [4].