Two new diterpenoids from the stems of Rhododendron dauricum as GABA_A receptor agonists

Abstract

Two new diterpenoids, dauricumins A (1) and B (2), together with two known aromatic meroterpenoids (3 and 4), were isolated from the petroleum ether soluble fraction of the stems from Rhododendron dauricum through an HPLC-MS-SPE-NMR combination strategy. The absolute configurations of 1 and 2 were elucidated by ECD calculations and [Rh₂ (OCOCF₃)₄]-induced CD spectrum analysis. In a membrane potential FLIPR assay, confluentin (4) showed an agonistic effect on GABA_A receptor (EC₅₀ = 20 µM).

Keywords:

• Ericaceae
• HPLC-MS-SPE-NMR; Rhododendron dauricum
• diterpenoids
• agonist of GABA_A receptors

Acknowledgements

We are grateful to the Department of Instrumental Analysis, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Mediacal College for measuring the IR, NMR, MS and HRESIMS.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by grants from the National Natural Science Foundation of China (grant nos. 21977119 and 22107120).