Scents and sensitivity.

Gossypol, a phenolic compound extracted from the cotton plant, has been used as an oral male contraceptive in China; few side effects other than transient hypokalaemia have been reported (Qian & Wang, 1984; Prasad & Diczfalusy, 1982). Recent reports using experimental tumour models indicate that gossypol may also be a potential anti-tumour chemotherapeutic agent (Wang & Rao, 1984; Tso, 1984; Tuszynski & Cossu, 1984). The structure of gossypol is shown in Figure 1; there is limited rotation about the inter-naphthyl bond giving rise to the chiral nature of the molecule. Gossypol, when extracted from the cotton plant, is a mixture of (+) and (-) enantiomers which have now been separated (Matlin & Zhou, 1984). Since it has been shown that the (-) enantiomer of gossypol is more effective than the racemic mixture in producing infertility in male hamsters (Matlin et al., 1985), this led us to examine the cytotoxicity of the enantiomers and the racemic mixture on normal and tumour-derived cells in culture. The (-) form of gossypol is more cytotoxic than the (+) form and the degree of toxicity is influenced by plasma proteins.