Discovery of Natural Products for Cancer Prevention.

"Cancer chemoprevention" is a term referring to the slowing or reversal of this disease, using nontoxic natural or synthetic compounds. For about 50 years, there has been a strong scientific interest in discovering plant-derived compounds to prevent cancer, and strategies for this purpose using a concerted series of in vitro, ex vivo, and in vivo laboratory bioassays have been developed. Five examples of the more thoroughly investigated agents of this type are described herein, which are each supported by detailed literature reports, inclusive of ellagic acid, isoliquiritigenin, lycopene, trans-resveratrol, and sulforaphane. In addition, extracts of the plants avocado (Persea americana), noni (Morinda citrifolia), açai (Euterpe oleracea), and mangosteen (Garcinia mangostana) have all shown inhibitory activity in an in vivo or ex vivo bioassay using a carcinogen and germane to cancer chemoprevention, and selected in vitro-active constituents are described for each of these 4 species.