3-Alkylpyridinium salts from Haplosclerida marine sponges: Isolation, structure elucidations, and biosynthetic considerations

A very little studied marine sponge Callyspongia sp. collected off the coast of Martinique was chemically investigated. The study led to the isolation and structure characterization of two new 3-alkylpyridinium salts which belonged to the recently isolated pachychaline family. Structures were elucidated by 1D, 2D NMR and detailed high-resolution electron spray ionization mass spectra (HRESIMS)-MS studies. The use of HRESIMS-MS studies proved to be highly efficient to identify two other close derivatives in a mixture. Finally, these studies allowed us to propose a general biosynthetic pathway leading to important 3-alkylpyridinium salts.