Sarain A is a complex macrocyclic marine alkaloid extracted from sponges of the order Haplosclerida. It is likely that this alkaloid shares a common origin with manzamine alkaloids, also extracted from sponges of the same order. In this paper, new concepts concerning this origin are presented and conSarain A is a complex alkaloid isolated from the sponge Reniera Sarai.[1] Despite its unique skeleton, it is believed to have the same biogenetic origin as other macrocyclic alkaloids extracted from sponges of the same order (Haplosclerida) such as, inter alia, manzamine A, halicyclamine A, keramaphidin B.[2] The basis for an understanding of this origin were initially formulated by Baldwin and Whitehead who proposed an original pathway for explaining the origin of keramaphidin B and manzamine A. This pathway involved formation of dihydropyridine intermediates from long-chain aminoaldehydes and acrolein, followed by intra- [a]