Figure 1.

The sequential discovery of podophyllotoxin-group of drugs. FDA approved anticancer drugs etoposide, teniposide and etopophos were derived from the parent compound podophyllotoxin, which was originally extracted from mayapple plant as a curative for various diseases. As the side-effects for podophyllotoxin and its primary derivatives became evident, less toxic derivatives such as TOP-53, NK611, GL-331, azatoxin and various others were designed and synthesized.