Levantilides A and B, 20-Membered Macrolides from a Micromonospora Strain Isolated from the Mediterranean Deep Sea Sediment

Two new 20-membered macrolides, levantilide A and B, were isolated from the Micromonospora strain M71-A77. Strain M71-A77 was recovered from an Eastern Mediterranean deep-sea sediment sample and revealed to produce the levantilides under in situ salinity of 38.6‰. The chemical structures of the levantilides were elucidated on the basis of different one- and two- dimensional NMR experiments. Levantilide A exhibits a moderate antiproliferative activity against several tumor cell lines.