Conisulfamines A-C, novel unique alkyl sulfoxides from the Mediterranean ascidian Aplidium conicum

Ascidians belonging to the Aplidium genus are characterized by a great chemiodiversity that includes nitrogenous and non-nitrogenous metabolites, this latter group being dominated by prenyl quinones/hydroquinones, linear or cyclic derivatives1. These compounds are generally known as meroterpenes. Recently, we analyzed a sample of Aplidium conicum collected in the Bay of Naples and, surprisingly, the pattern of its secondary metabolites resulted very different from that of other samples of A. conicum previously investigated. In fact, the ascidian is completely lacking in meroterpenoids, whilst the main components of its methanolic extract are a new class of molecules, unsaturated linear alkylsulfoxides, whose major constituents are Conisulfamines A, B, and C. The structures of the new compounds have been elucidated through an extensive application of MS, 1H, 13C and 2D homo-and heteronuclear-NMR techniques. The stereochemical analysis of Conisulfamine A has been carried out in a three stages–approach, relying on the combination of NMR spectroscopy and computational methods.