A new 24-membered lactone and a new polyene delta-lactone from the marine bacterium Bacillus marinus.

A new 24-membered macrolide macrolactin T (1), and a new polyene delta-lactone macrolactin U (2), along with macrolactins A, B, D, O, and S, were isolated from the cultured broth of the bacterium Bacillus marinus, which was isolated from Suaeda salsa collected in the coastline of Bohai Sea of China. The structures of 1 and 2 were elucidated on the basis of extensive spectroscopic data analyses. The inhibitory activity of macrolactins T, B and D against fungi Pyricularia oryzae and Alternaria solani, and bacteria Staphylococcus aureus is reported.