New neo-clerodane diterpenes from Teucrium polium subsp. capitatum

Teucrium polium subsp. capitatum (syn. Teucrium capitatum, Lamiaceae), popularly known as golden or felty germander, is a deciduous shrub that abundantly grows in Mediterranean regions of Europe, Northern Africa and Southwest Asia. The aerial parts are traditionally used in Algeria as a decoction or ointment in the treatment of hypertension, diabetes and wounds. In a previous study we reported the wound healing properties of a methanolic extract in a wound excision model in rabbits, and a comprehensive polyphenolic profile of this extract [1]. Further investigation of the methanolic extract focusing on the non-phenolic constituents afforded six furanoid neo-clerodane diterpenes, including 20-acetylauropolin and 6- acetylteucjaponin A, along with four previously undescribed congeners. The compounds were isolated by preparative HPLC-ESIMS after silica gel column chromatography. Their structures were established by extensive NMR analysis, HRESIMS, and by comparison with literature data of related compounds. The absolute configuration of 20-acetylauropolin was confirmed by single crystal X-ray crystallographic analysis. Some of the isolated diterpenes possess structural features uncommon in neo-clerodane diterpenes, such as a rare C-20 hemiacetal function forming an oxepane ring to C-7 of the trans-decalin core structure in teupocapin C ([Fig. 1]).

Fig. 1 Structure of teupocapin C.

 

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Conflict of Interest

The authors declare no conflict of interest.

• References

• 1 Chabane S., Boudjelal A., Keller M., Doubakh S., Potterat O.. Teucrium polium – wound healing potential, toxicity and polyphenolic profile, South African J. Bot. 2021; 137: 228-235

Publication History

Article published online:
16 November 2023