Polycyclic Aromatic Alkaloids, XI A Convenient Formal Total Synthesis of the Cytotoxic Marine Alkaloid Amphimedine

Bioinspired Syntheses of the Pyridoacridine Marine Alkaloids Demethyldeoxyamphimedine, Deoxyamphimedine, and Amphimedine

Efficient bioinspired syntheses of the biologically active pyridoacridine marine alkaloids demethyldeoxyamphimedine, deoxyamphimedine, and amphimedine are reported. Reaction of styelsamine D, prepared via an optimized route starting from Boc-dopamine, with paraformaldehyde afforded demethyldeoxyamphimedine and deoxyamphimedine. Oxidation of the latter using either K3[Fe(CN)6] or DMSO/conc. HCl gave amphimedine in 8 steps from tryptamine with an overall yield of 14%. The versatility of the method was demonstrated by the synthesis of non-natural ethyl and benzyl congeners of deoxyamphimedine and amphimedine.

An improved high yield total synthesis and cytotoxicity study of the marine alkaloid neoamphimedine: an ATP-competitive inhibitor of topoisomerase IIα and potent anticancer agent

Recently, we characterized neoamphimedine (neo) as an ATP-competitive inhibitor of the ATPase domain of human Topoisomerase IIα. Thus far, neo is the only pyridoacridine with this mechanism of action. One limiting factor in the development of neo as a therapeutic agent has been access to sufficient amounts of material for biological testing. Although there are two reported syntheses of neo, both require 12 steps with low overall yields (≤6%). In this article, we report an improved total synthesis of neo achieved in 10 steps with a 25% overall yield. In addition, we report an expanded cytotoxicity study using a panel of human cancer cell lines, including: breast, colorectal, lung, and leukemia. Neo displays potent cytotoxicity (nM IC50 values) in all, with significant potency against colorectal cancer (lowest IC50 = 6 nM). We show that neo is cytotoxic not cytostatic, and that neo exerts cytotoxicity by inducing G2-M cell cycle arrest and apoptosis.