A variety of studies on the modification of combretastatin A-4 triggered our interest in the impact of the linkers between the 3, 4, 5-trimethoxyphenyl ring and 5-amino-6- methoxyquinoline on biological activity. The replacement of the carbonyl group with bond, amine, ether, sulfide, and sulfone groups was evaluated in this study. The results showed that compounds 14 and 15 containing sulfide and sulfone groups between the 3, 4, 5- ...