Antivascular and anticancer activity of dihalogenated A-ring analogues of combretastatin A-4

The generally accepted view is that the 3,4,5-trimethoxy-substituted aromatic A-ring of combretastatin A-4 (CA-4) and its analogues should be conserved in order to maintain biological activity through enforcing an active molecular conformation. Contrary to this, we have found that substituting the larger meta-methoxy groups of CA-4 with smaller halogen atoms results in compounds that are equipotent or more potent than CA-4 itself in vitro.