|Stipanovic, Robert - Bob|
Submitted to: Genetic Control of Cotton Fiber and Seed Quality Workshop
Publication Type: Proceedings
Publication Acceptance Date: 12/5/2000
Publication Date: 12/15/2001
Technical Abstract: The potential use of cottonseed that contains high levels of the (+)-enantiomer of gossypol as a feed and food source is reviewed. Gossypol, which is found naturally in cottonseed, is toxic to non-ruminants and thus makes cottonseed unsuitable for consumption by these animals. Gossypol is formed by the bimolecular free radical coupling of hemigossypol lto form gossypol. These free radical reactions are high-energy reactions that normally do not exhibit either regio- or stereospecificity. Yet, in a variety of plant species, the free radical coupling reaction of E-coniferyl exhibits both regio- and stereospecificity giving either (+)- or (-)- pinoresinol. Recent work by others has elegantly resolved this conundrum by demonstrating the intervention of what is call a dirigent protein. The dimerization of hemigossypol to form gossypol is regiospecific. That is, a new binaphthyl bond is formed exclusively between C-2 and C-2'. The dimerization is also stereospecific since one enantiomer is produced in preference to the other. The biologically activity of pure (+)- and (-)- gossypol have been studied on various types of cancer cells, viruses, enzymes, ameba and whole animals. In almost all cases (-)-gossypol is the more biologically active (i.e., toxic). A recent study showed that (-)- gossypol was toxic to chickens while (+)-gossypol showed no adverse effects. Over 34 million metric tons of cottonseed were produced world wide in 1997. If 5% were retained for replanting, the remainder represents 7.27 million metric tons of protein that could be available for non- ruminant (including human) consumption if the cottonseed was free of toxic (-)-gossypol. This would provide the protein needs for 348M people (5.8% of the world's population) for one year.