Synthesis and cytotoxicity of novel 20-O-linked homocamptothecin ester derivatives as potent topoisomerase I inhibitors.

In an attempt to improve the antitumor activity of homocamptothecins (hCPTs), a series of novel 20-O-linked hCPT ester derivatives were first designed and synthesized based on a synthetic route, by which hCPTs are acylated with different substituted phenoxyacetic acid ester derivatives. Most of the derivatives were assayed for in vitro cytotoxicity against six human cancer cell lines KB, KB/VCR, A549, HCT-8, Bel7402, and A2780, and most of the assayed compounds exhibited good antiproliferative activity on these tumor cell lines especially on KB.