Calyculin

Calyculins are natural products originally isolated from the marine sponge Discodermia calyx. Calyculins have proven to be strong serine/threonine protein phosphatase inhibitors and based on this property, calyculins might be potential tumor-promoting agents.
A laboratory synthesis of calyculin A has been reported.

Biosynthesis

Calyculin A is biosynthesized as a pyrophosphate containing phosphocalyculin A protoxins by a hybrid PKS-NRPS pathway within the sponge bacterial symbiont, "Candidatus Entotheonella" sp.