The present invention provides new naphthylisoquinoline derivatives. In particular, the present invention furthermore provides novel dimeric arylisoquinoline alkaloids comprised of coupled first and second arylisoquinoline monomers. Monomeric and dimeric compounds of the present invention have medically useful properties, such as antimicrobial properties, more specifically such as antimalarial and antiviral properties. Monomeric compounds of the present invention are also useful as building blocks or intermediates for synthesis of novel dimeric arylisoquinoline alkaloids. Monomeric and dimeric compounds of the present invention may be obtained in substantially pure form by total synthesis, partial synthesis, or derivatization from known synthetic or naturally occurring compounds, and by isolation and purification from plants of the Dioncophyllaceae and Ancistrocladaceae families.