Sesquiterpenes from Chrysoma Pauciflosculosa

Abstract

The aerial parts of Chrysoma pauciflosculosa (syn. Solidago pauciflosculosa) gave two new sesquiterpenes, (+)-β-turmerone and a bisabolane endoperoxide, together with the known (-)-α-trans-bergamotene and (+)-β-sesquiphellandrene. When exposed to air and light, (+)-β-turmerone and (+)-β-sesquiphellandrene gave oxidative degradation products, involving hydroperoxide intermediates. Photosensitized singlet oxygen reactions of (+)-β-turmerone provided a series of bisabolane-type endoperoxides. The structures of the natural compounds as well as those of the degradation products and derivatives were elucidated by chemical and spectroscopic methods, mainly NMR and MS. Aqueous solutions of (+)-β-turmerone,(+)-β-sesquiphellandrene and (-)-α-trans-bergamotene were tested for their effects on the germination and radicle growth of three Florida sandhill species, Rudbeckia hirta, Schizachyrium scoparium, Leptochloa dubia, as well as Lactuca sativa. (+)-β-Turmerone significantly inhibited germination of L. sativa, stimulated radicle growth of L. sativa and S. scoparium at the 10^?4 M level, and mildly inhibited radicle growth of R. hirta, as did (+)-β-sesquiphellandrene. (-)-α-trans-Bergamotene stimulated germination of S. scoparium and L. sativa and significantly enhanced radicle growth of S. scoparium.