“…Pyridine is a privileged N-heterocyclic scaffold found in the structures of many natural products and biologically active compounds. Their significance in terms of clinical applications has been demonstrated by their consistent incorporation into a variety of drug candidates. , Among pyridine-containing natural products, those with N-substituted pyridinium moieties have mainly been isolated from marine organisms, especially sponges, , with the 1,3-dialkylpyridinium scaffold most frequently found in sponge metabolites; monomeric and di- or trimeric pyridinium derivatives ,,− and polymers − have been reported. Agelongine and trigonelline are also 1,3-disubstituted derivatives that contain carboxylate substituents at C-3 instead of alkyl chains derived from fatty acids. , The spongidines have unique structures in which the D-ring of the scalarane scaffold is substituted with a pyridinium .…”