Gossypol, a disesquiterpene from cottonseed, exhibits multiple biological properties, including male antifertility activity and anticancer activity. Gossypol also inhibits the growth of numerous parasitic organisms and shows antiviral activity against a number of enveloped viruses, including the AIDS virus. Derivatives of gossypol, in which the aldehyde functional groups that contribute to toxicity have been modified, retain or even show enhanced biological activity. Ring substituted 2,3-dihydroxy- 1-naphthoic acids, which are structural analogs of gossypol, share with gossypol the ability to complex with dehydrogenases at the dinucleotide fold (Rossmann fold) with selectivity, suggesting that gossypol may be considered the prototype of a new class of drugs targeted to dehydrogenases. Most of the biological activities of gossypol and related compounds may result from inhibition of dehydrogenases.