Gabosines L, N and O: New carba-sugars from Streptomyces with DNA-binding properties

In addition to the known gabosines A (4), B (5) and C (6), three new gabosi nes L (1), N (2) and O (3) were detected by chemical screening as secondary metabolites of Strep- tomyces (strains GT 041230, GT 051024 and S 1096). T he constitutions of 1, 2 and 3 were established by spectroscopic techniques and derivatization reactions. The absolute stereochemistry of 1 and 2 was determined by Helmchen's method and has been verified in the case of gabosi ne N (2) by X-ray analysis. The DNA-binding properties of the gabosines wer e investigated and analyzed by binding studies using a recently developed t hin-layer chromatography technique (bimolecular-chemical screening).