Antimicrobial terpenoids of Gossypium: Hemigossypol, 6-methoxyhemigossypol and 6-deoxyhemigossypol

Abstract

The sesquiterpenoid aldehydes, hemigossypol ( 1a), 6-methoxyhemigossypol ( 1b), and 6-deoxyhemigossypol ( 1c), were isolated and identified from Verticillium-infected stele tissue of Gossypium barbadense. Structures were established by spectral (UV, IR, NMR, MS) evidence and chemical transformations. This is the first report of ( 1b) and ( 1c) in nature, and of NMR and m.p. data for crystalline pure ( 1a). Compound ( 1a) occurred in diseased stele tissues of all 21 Gossypium species examined and in the genera, Cienfuegosia, Gossypioides, Hampea, and Thespesia; it was absent in three Hibiscus spp. Compound ( 1b) occurred in the same taxa as ( 1a), except that it was absent in species of two cytogenetic groups (A and B genome) of Gossypium. Compound ( 1c) occurred in trace quantities, or was not detected, in most species; however, its distribution appeared to besimilar to that