Secondary metabolites by chemical screening, 18. Narbosines, new carbohydrate metabolites from Streptomyces

Abstract In the culture broth of two new Strepomyces strains several novel 2,3,6‐trideoxy‐ L ‐ threo ‐hexose (rhodinose) metabolites, narbosines A to E ( 2–6 , 8 , 9 ), were detected besides α‐ N ‐acetylanhydro‐ L ‐ornithine ( 11 ) by using the chemical screening method. Their structures were deduced from spectroscopical data as well as from chemical transformations. Narbosine A ( 2/3 ) was shown to be a 1:1 anomeric mixture of α‐ L ‐rhodinopyranosyl‐(1→4) ‐α/β‐ L ‐rhodinopyranose, the others are partially oxidatively and reductively transformed derivatives of 2/3 . A destinct antiviral activity was observed for the described metabolites.