Four new sesquiterpenes from the rhizomes of Curcuma phaeocaulis and their iNOS inhibitory activities

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.

Keywords::

• Curcuma phaeocaulis
• guaiane
• germacrane
• sesquiterpenes
• nitric oxide

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.

Additional information

Funding

This work was financially supported by grants in part from the National Natural Science Foundation of China (NSFC) [grant number 30973630], [grant number 81430095]; and the Medicinal Chemistry Subject Construction Project of Shenyang Pharmaceutical University [grant number 20130017].