Wollamides: Antimycobacterial Cyclic Hexapeptidesfrom an Australian Soil Streptomyces.

A soil Streptomycesnov. sp. (MST-115088) isolatedfrom semiarid terrain near Wollogorang Station, Queensland, returnedtwo known and two new examples of a rare class of cyclic hexapeptide,desotamides A and B (1and 2) and E andF (3and 4), respectively, together withtwo new d-Orn homologues, wollamides A and B (5and 6). Structures were assigned by detailed spectroscopicand C3Marfey’s analysis. The desotamides/wollamidesexhibit growth inhibitory activity against Gram-positive bacteria(IC500.6–7 μM) and are noncytotoxic to mammaliancells (IC50>30 μM). The wollamides exhibit antimycobacterialactivity (IC502.8 and 3.1 μM), including reductionin the intracellular mycobacterial survival in murine bone marrow-derivedmacrophages. [ABSTRACT FROM AUTHOR]