Novel antitumor agents from higher plants

This review article describes research on cytotoxic natural products isolated from plant sources, primarily preclinical lead identification and structural modification studies performed in the Natural Products Laboratory of Dr. K, H. Lee. As a result of this work, more than 100 new cytotoxic antitumor compounds and their synthetic analogs have shown confirmed activity in NCI's in vitro human tumor cell lines bioassay and are of current interest to NCI for further in vivo evaluation. A significant and ongoing project involves novel antitumor analogs related to podophyllotoxin and etoposide, and has led to a potent derivative designated GL331 (17). This compound is currently in Phase IIa clinical trials and shows promise as an anticancer drug, especially for drug-resistant cancers. Bioactivity-directed fractionation and isolation of medicinal herbs (primarily herbs of Chinese origin) have also led to many classes of cytotoxic compounds including polyphenolic compounds, sesquiterpene lactones, lignans, quassinoids, triterpene glucosides, flavonoids, colchicine derivatives, and quinone derivatives. (C) 1999 John Wiley & Sons, inc.