Structure and activity of lobophorins from a turrid mollusk-associated Streptomyces sp

A novel lumun-lumun sampling methodology was used to obtain a large diversity of micromollusks, including the new species Lienardia totopotens . In turn, from L. totopotens we cultivated a Streptomyces sp. strain that contained new and known spirotetronate polyketides, lobophorins (1–5). The structures were elucidated using spectroscopy, and the compounds were evaluated for cytotoxicity to human cells and activity against Mycobacterium tuberculosis , Bacillus subtilis , Pseudomonas aeruginosa and Burkholderia cepacia . Compounds 2–5 showed varying degrees of activity against human cells, M. tuberculosis and B. subtilis in the low μ M to mid n M range but were inactive against the other strains, while 1 lacking digitoxose was inactive. Very slight structural changes in 2–5 led to varying antibacterial:cytotoxicity ratios, providing a possible basis to synthesize more selective derivatives.