Mechanism of drug and toxic actions of gossypol: focus on reactive oxygen species and electron transfer.

Gossypol, a constituent of cottonseeds, displays various drug properties, including antifertility and anticancer. Toxicity is shown against the reproductive system, heart, liver, and membranes. The compound exhibits pro- and anti-oxidant behavior. Electron transfer (ET) functionalities, present in gossypol and its metabolites, comprise conjugated dicarbonyl, a quinone derivative, Shiff bases, and metal complexes. The parent possesses a reduction potential favorable for in vivo ET. Considerable evidence points to oxidative stress (OS), formation of reactive oxygen species (ROS), and DNA scission, characteristics of redox cycling by ET in biosystems. Mechanistic aspects are addressed with OS-ROS-ET as the guiding theme, in addition to other modes of action resulting in a multifaceted scenario.