title: Total and percent atropisomers of gossypol and gossypol-6-methyl ether in seeds from pima cottons and accessions of Gossypium barbadense L.
abstract: Gossypol occurs naturally in the seed, foliage, and roots of the cotton plant ( Gossypium ) as atropisomers due to restricted rotation around the binaphthyl bond. The atropisomers differ in their biological activities. (-)-(R)-Gossypol is more toxic and exhibits significantly greater anticancer activity than the (+)-(S)-atropisomer. Most commercial Upland ( Gossypium hirsutum ) cottonseeds have an (R)- to (S)-gossypol ratio of approximately 2:3, but some Pima ( Gossypium barbadense ) seeds have an excess of (R)-gossypol. There is no known source of cottonseed with an (R)- to (S)-gossypol ratio of greater than approximately 70:30. Cottonseed with a high percentage of (R)-gossypol would be of value to the pharmaceutical industry. It was theorized that G. barbadense cotton might be a source of this desirable high (R)-gossypol seed trait. There are 671 different accessions of G. barbadense in the U.S. Cotton Germplasm Collection, few of which had been characterized with respect to their (R)- to (S)-gossypol ratio. This work completed that analysis and found considerable variation in the atropisomer ratio. Approximately half of the accessions have an excess of (R)-gossypol, and 52 accessions have essentially a 1:1 ratio. The highest percentage of (R)-gossypol was found in accessions GB26 (68.2%) and GB283 (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%). These accessions may be useful in a breeding program to reduce (R)-gossypol in Pima seed, which is a concern to the dairy industry because of the toxicity and male antifertility activity of this atropisomer. Also, GB710 was devoid of gossypol.
authors.affiliation: Southern Plains Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, College Station, Texas 77845, USA. rdstip@cpru.usda.gov
authors.forename: Robert D
authors.initials: RD
authors.lastname: Stipanovic
authors.forename: Lorraine S
authors.initials: LS
authors.lastname: Puckhaber
authors.forename: Jinggao
authors.initials: J
authors.lastname: Liu
authors.forename: Alois A
authors.initials: AA
authors.lastname: Bell
mesh_terms: D003433:Crosses, Genetic; D005838:Genotype; D003368:Gossypium / Q000737:chemistry* / Q000235:genetics; D006072:Gossypol / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry* / Q000235:genetics
chemical_list: D006072:Gossypol