Abstract
Three new guaiane-type sesquiterpenes named phaeocaulisins K-M (1–3), and one germacrane-type sesquiterpenoid with new ring system of 1,5- and 1,8-ether groups named phagermadiol (4), were isolated from rhizomes of Curcuma phaeocaulis. Their structures were established based on extensive spectroscopic analysis. Compound 1, the first example of norsesquiterpene with tropone backbone, and compound 3 with a novel 1,2-dioxolane sesquiterpene alcohol were isolated from the genus Curcuma. All of the isolated compounds were tested for inhibitory activity against lipopolysaccharide-induced nitric oxide (NO) production in RAW 264.7 macrophages. Compound 3 inhibited NO production with IC50 value of 6.05 ± 0.43 μM. The plausible biosynthetic pathway for compounds 3 and 4 in C. phaeocaulis was also discussed.
Acknowledgements
We are grateful to Dr Paul Owusu Donkor for refining the language of our manuscript.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes
Dedicated to Professor Xin-Sheng Yao on the occasion of his 80th birthday.