ARS | Publication request: Percent Artropisomers of Gossypol in Seeds from Accessions of Gossypium barbadense

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 16, 2008
Publication Date: N/A

Technical Abstract: Gossypol occurs naturally in the seed, leaves and roots of the cotton plant (Gossypium) as two atropisomers due to restricted rotation around the binaphthyl bond. The atropisomers differ in their biological activity. (-)-(R)-Gossypol exhibits significantly greater anti-cancer activity than the (+)-(S)-enantiomer. Most commercial cottonseed have a 20% enantiomeric excess (ee) in S, but some Brazilian moco cottons (G. hirsutum var. marie galante) have a 96% ee in S. There is no known source of cottonseed with a >60% ee in R. Cottonseed with a high ee in R would be of value to the pharmaceutical industry. Commercial G. barbadense (Pima type) cottonseed may be a source of (R)-gossypol. There are 667 different accessions of G. barbadense in the U.S. Cotton Germplasm Collection, and the S to R ratio in the seed of most of these has not been determined. We have completed that analysis and found considerable variation in the atropisomer ratio. Approximately half of the accessions have an excess of (S)-gossypol, and 52 accessions have an ee <1%. The highest percentage of (R)-gossypol was found in accessions GB26 (68.2%) and GB 283 (67.3%). Surprisingly, five accessions had 5% or less of (R)-gossypol: GB516 (5.0%), GB761 (4.5%), GB577 (4.3%), GB719 (3.7%) and GB476 (2.3%). Also GB710 was glandless (no gossypol).