Borrelidins F-I, cytotoxic and cell migration inhibiting agents from mangrove-derived Streptomyces rochei SCSIO ZJ89.

Borrelidin A (1) is produced by several species of Streptomyces and within its bioactive scaffold, the vinylic nitrile moiety is essential for activity. We report herein newly discovered members of the borrelidin family, borrelidin F (2), borrelidin G (3), borrelidin H (4) and borrelidin I (5); all were isolated from Streptomyces rochei SCSIO ZJ89 originating from a mangrove-derived sediment sample. These structurally diverse metabolites enabled a number of new structure-activity relationships (SARs) to be identified, especially with respect to the different configurations at the C11-OH and C12-C15 double bonds for which the absolute configurations were determined using spectroscopic methods. Importantly, borrelidin H (4) was found to have a therapeutic window superior to that of borrelidin A (1) in vitro and could inhibit migration of cancer cells.