Polypropionates from Bulla occidentalis: chemical markers and trophic relationships in cephalaspidean molluscs

A chemical investigation on the cephalaspidean Bulla occidentalis from the Gulf of Mexico led to known niuhinones A (1) and B (2) along with a new acyclic polypropionate, named niuhinone C (3). A complete NMR assignment of niuhinone A has been achieved by spectroscopic experiments, thus revising the Δ14 configuration. The occurrence of structurally related polypropionates in Bullidae species from different geographical areas is in agreement with a de novo origin in this family of molluscs and adds a further piece of evidence on prey–predator relationships among cephalaspideans.