Aminorifamycins and Sporalactams Produced in Culture by a Micromonospora sp. Isolated from a Northeastern-Pacific Marine Sediment Are Potent Antibiotics

The new ansa macrolide
antibiotics 1 to 4 have been isolated from
cultures of a Micromonospora sp. obtained from a
marine sediment. Rifamycins 1 and 2 are
the first natural ansa macrolides to have a 3-amino
substituent. Sporalactams A (3) and B (4) are comprised of a heterocylic core 5 and a 14-membered
ansa bridge that are both unprecedented. Sporalactam B (4) shows selective and potent inhibition of Mycobacterium
tuberculosis.