Vithuy Dao

Synthesis and cytotoxicity of gossypol related compounds.

Gossypol, gossypolone, reduced gossypol and new Schiffs bases of racemic gossypol and gossypolone were extracted or synthesized. Their cytotoxic activities on KB human cancer cells were determined. Gossypolone and the ethylamine derivative of gossypolone were the most active compounds (IC(50) in the micromolar range in both cases). The cytotoxicity of gossypol and gossypolone was increased when the tests were performed in the absence of serum and decreased when catalase as well as mannitol were added to the culture medium.

New thioderivatives of gossypol and gossypolone, as prodrugs of cytotoxic agents.

New dithiane or dithiolane derivatives of gossypol and gossypolone were synthesized with dithiolethane or dithiolpropane in the presence of BF(3)/Et(2)O. These thioderivatives exhibited low toxicity on KB cells (human epidermoid carcinoma cells of the mouth). They react easily with electrophiles in aprotic solvents to regenerate gossypolone or to form dehydrogossypoldithianes and dehydrogossypoldithiolanes, which display higher toxicity on KB cells. In addition, the low toxicity of gossypol thioderivatives was reversed by nitric oxide donors in physiological media. These experiments suggest that gossypol and gossypolone dithianes and dithiolanes can be used as prodrugs that target tumor cells surrounded by high concentrations of nitric oxide.