Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 15, 2005
Publication Date: June 20, 2005
Citation: Stipanovic, R.D., Puckhaber, L.S., Bell, A.A., Percival, Jr, A.E., Jacobs, J. 2005. Occurrence of (+)- and (-)-gossypol in wild species of cotton and in Gossypium hirsutum marie-galante. Journal of Agricultural and Food Chemistry. 53:6266-6271. Interpretive Summary: Cottonseed cannot be fed to non-ruminant animals because it contains a naturally occurring toxic compound called gossypol. Gossypol occurs in two forms referred to as either (+)-gossypol or (-)-gossypol. The toxicity of gossypol is associated only with (-)-gossypol. Most Upland commercial cottonseed contains about 1.5 times more (+)-gossypol than (-)-gossypol, while Egyptian (also called "Pima") cottonseed contains about 1.5 times more (-)-gossypol than (+)-gossypol. Cottonseed that contains <3% (-)-gossypol could probably be fed safely to non-ruminant animals. Interestingly, (-)-gossypol has unique antibacterial, antifungal and antiviral properties. Thus, cottonseed that contained <3% (+)-gossypol could be of value for medicinal applications. The variations in the (+)- to (-)-gossypol ratio in wild cotton species had not been determined. We have completed an analysis of all wild species in the U.S. National Cotton Germplasm Collection. We also analyzed all accessions in the Collection that are referred to as Upland cotton "marie-galante", from which high (+)-gossypol cottonseed had previously been identified. Within the Upland cotton "marie-galante" we found seven accessions with more than 94% (+)-gossypol. One accession (#2469) had >97% (+)-gossypol. Among the wild species no accessions were found that contained >90% of either (+)- or (-)-gossypol. However, several wild species were identified with a (+)- to (-)-ratio of approximately 2:3. Previously Egyptian cotton was the only species known to produce more (-)-gossypol than (+)-gossypol. There does not appear to be any source that could be used to breed for high levels of (-)-gossypol, but accession #2469 might be useful for breeding high levels of (+)-gossypol in cottonseed.
Technical Abstract: Due to restricted rotation about the binaphthyl bond, the dimeric sesquiterpenoid gossypol occurs as a chiral compound in cottonseed. The gossypol enantiomers exhibit different biological activities. The (-)-enantiomer is toxic, but also has potential medicinal uses. Thus, cottonseed with >95% (-)-gossypol could have biopharmaceutical applications. Conversely, cottonseed with >95% (+)-gossypol could be more readily utilized as a feed for animals. The (+)- to (-)-gossypol ratio in commercial Upland (Gossypium hirsutum) cottonseed is usually about 3:2 while that in commercial Pima cottonseed (G. barbadense) is approximately 2:3. We have determined the (+)- to (-)-gossypol ratios in the seed from all wild species of cotton and of accessions within G. hirsutum marie-galante within the U.S. Cotton Germplasm Collection. We report for the first time that in addition to G. barbadense, some or all of the accessions from six wild species (i.e., G. darwinii, G. sturtianum, G. areysianum, G. longicalyx, G. harknessii and G. costulatum) also produce an excess of (-)-gossypol. However, in accessions showing an excess of (-)-gossypol, the (+)- to (-)-ratio was not significantly different from that found in G. barbadense. However, among the 94 accessions of G. hirsutum marie-galante, we found one accession (#2469) that contained >97% (+)-gossypol.