Structure activity relationships of synthetic antibiotic analogues of chryscandin

Anti-yeast activity with a series of chryscandin derivatives showed that the O-methyl-L-tyrosyl moiety is not always required for activity at the target site. On the other hand, the adenyl-3'-aminoribofuranuronic acid moiety seems to be essential for biological activity. Therefore, the various acyl derivatives on the amino group of the sugar part of the nucleoside were synthesized. 1-(6-Amino-9H-purin-9-yl)-3-(S-benzyl-L-cysteinylamino)- 1,3-dideoxy-beta-D-ribofuranuronic acid (16) showed the highest efficacy among them against Candida albicans. It exhibited sixteen-fold enhanced activity in vitro compared with that of native chryscandin. The in vivo activity of 16 against experimental infection of C. albicans showed the almost same as that of 5-fluorocytosine and a superior to that of ketoconazole.