Streptomyces hygroscopicus var Limoneus

Validamycin A is the only commercial fungicide active against this target (Figure 4.9). The compound is an aminoglycosidic pseudosaccharide and is a secondary metabolite produced in the fermentation of Streptomyces hygroscopicus var. limoneus. Validamycin A was introduced by Takeda Chemical Industries Ltd. for the control of Basidiomy-cetes and Corticiaceae, especially sheath blight, Rhizoctonia solani, in rice. 

The first evidence for aminocarbapyranoses occurring in Nature dates back to early 70s with the discovery of validamine 202 (Chart 3), a carbasugar constituent of Validamycins, an antibiotic complex which shows growth inhibition activity against bacterial diseases of rice plants [50]. Shortly after, validamine 202, along with valiolamine 203 and valienamine 204, (Chart 3), were isolated from the fermentation broth of Streptomyces hygroscopicus var. limoneus [50],... 

Valiolamine (89), an aminocyclitol produced by Streptomyces hygroscopicus var. limoneus, is a potent inhibitor of pig intestinal maltase and sucrase, with IC50 values of 2.2 and 0.049 pM, respectively [107]. Numerous iV-substituted valiolamine derivatives were synthesized to enhance its a-glucosidase inhibitory activity in vitro and the very simple derivative voglibose (90), which is obtained by reductive amination of valiolamine with dihydroxyacetone, was selected as the potential oral antidiabetic agent [108]. Its IC50 values toward maltase and sucrase were 0.015 and 0.0046 pM, respectively. Voglibose (the brand name Basen) has been commercially available for the treatment of type 2 diabetes in Japan since 1994. 

C,4H25N09 351.353 Isol. from Streptomyces hygroscopicus var. limoneus. Amorph. solid + H2O. Sol. H2O, MeOH, DMSO poorly sol. EtOH, Mc2CO, hexane. [a]o +118.6(c, 1 inH20). 

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