This chapter describes isolation and structure elucidation of naphthylisoquinoline alkaloids, other alkaloids from the Dioncophyllaceae (West Africa), new alkaloids from Asian Ancistrocladaceae species, alkaloids of African Ancistrocladaceae species, the michellamines: a new class of naturally occurring quateraryls and related compounds, stereocontrolled synthesis of mono- and dimeric naphthylisoquinoline alkaloids, biogenetic origin of naphthylisoquinolline alkaloids, and the chemo-ecological context of naphthylisoquinoline alkaloids. The typical isolation procedure involves extractions of dried and ground root bark material, consecutively with petroleum ether and dichloromethane/NH3, followed by chromatography of the alkaloid-containing CH2Cl2, extracts on SiO2. The bioassay-guided search for new active compounds yields the discovery of the michellamines, a new class of antiviral agents with an unprecedented quateraryl framework, produced by a previously unknown plant species, A.korupensis. The challenging molecular structures of the alkaloids triggers the development of new synthetic methods for the regio- and stereoselective construction of highly hindered biaryl axes. Initial feeding experiments show that the naphthylisoquinoline alkaloids are also unique with respect to their biogenetic origin from acetate units—and not from aromatic amino acids. © 1995, Academic Press, Inc.