Bioactivities of gossypol, 6-methoxygossypol, and 6,6'-dimethoxygossypol.

6-Methoxygossypol and 6,6'-dimethoxygossypol were recently isolated from the root tissue of cotton plants. Together with gossypol, these natural products were investigated for a wide range of bioactivities. Antioxidant effects, the potential to prevent DNA damage, anticancer activity, and antitrypanosomal effects were studied. The 6-methoxygossypol generally exhibited equal bioactivities to the 6,6'-dimethoxygossypol, but gossypol showed greater activities than both methylated derivatives in scavenging free radicals, reducing ferric ions, and preventing UV-induced DNA damage. All three compounds inhibited the growth of cervical (SiHa), breast (MCF-7), and colon (Caco-2) cancer cells. At >/=5 ppm of test concentrations, 6,6'-dimethoxygossypol showed a stronger ability than gossypol to inhibit the growth of Trypanosoma brucei cells.