Quantitative Determination of (+)- and (-)-Gossypol in Flower Petals of Selected Cotton Cultivars Using Capillary Zone Electrophoresis

 Cottonseed provides a high quality protein that is currently under utilized because of the presence of a toxic compound called gossypol.  Gossypol is biosynthesized by the free radical coupling of two molecules of hemigossypol.  This coupling reaction produces two optically active enantiomers.  One of these is referred to as (+)-gossypol, and the other as (-)-gossypol. In commercial cottons they occur in an approximate ratio of 3:2.  Preliminary experiments show, that cottonseed containing high  levels of (+)-gossypol, can be safely fed to chickens.  We are currently pursuing a breeding program to create germplasm with high levels of (+)-gossypol in the seed.   To monitor our crosses, we initially analyze flower petals, which provides an indication of the (+)- to (-)-gossypol content that will result in the seed; seed analysis is used to confirm those plants with the highest levels of (+)-gossypol.  This requires a quantitative method to determine the ratio of (+)- to (-)-gossypol.  HPLC methods have been developed for this purpose.  However, we now report a new method to determine this ratio using capillary electrophoresis (HPCE) on extracts from flower petals.  HPCE is a versatile method of analysis that has wide applications in various areas of analytical chemistry.  It is noteworthy for its simplicity, accuracy,  and reproducibility, which  allow it to be used on a daily basis in the laboratory.  In the case of the analysis for (+)- and (-)-gossypol, the UV spectrum of the two peaks corresponding to the enantiomers of gossypol obtained by HPCE, are identically to the gossypol standard.  Experimental conditions of the analysis will be reported.