Submitted to: Chirality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/30/2003
Publication Date: 5/15/2003
Citation: Dowd, M.K. 2003. Preparation of enantiomeric gossypol by crystallization. Chirality. 15(6):486-493. Interpretive Summary: Gossypol is a natural product of the cotton plant that has a wide spectrum of bioactivity including anti-cancer and anti-fertility effects. The compound exists in two forms and current research suggests that the forms do not contribute equality to the compound's properties. To study these activity differences, improved methods are needed to separate or prepare the individual gossypol forms. In this work, gram quantities of both gossypol forms were prepared based on a crystallographic separation approach. The procedure will be useful to researchers studying the anti-cancer properties of this natural product.
Technical Abstract: Large enantiomorphoric crystals of gossypol-acetone (1:3) were grown from acetone solutions of racemic gossypol-acetic acid (1:1) at 4 OC. By controlling the initial gossypol concentration, crystallization time, and solution volume, single crystals were grown that weighed > 50 mg, equivalent to > 37 mg of enantiomeric gossypol. Even larger crystals were possible, but it was difficult to produce these reliably without contamination of the antipode. Storing the product crystals under vacuum for 3 to 4 days removed essentially all of the occluded acetone. By employing these techniques, gram quantities of enantiomeric gossypol were prepared in high chemical and optidal purity. The principal limitation of the method is the need to determine the form and purity of each product crystal. Nevertheless, the method competes favorably with preparative-scale chromatographic procedures based on separating gossypol diastereomers.