New Cytotoxic Bis-labdanic Diterpenoids from Alpinia calcarata

Abstract

Two novel bis-labdanic diterpenoids named calcaratarin D and calcaratarin E were isolated from the rhizomes of Alpinia calcarata. Their structures were elucidated as a pair of stereoisomers on the basis of the spectral evidence. 2D NMR techniques including ¹H-¹H COSY, HMQC, HMBC, NOESY spectra and HRFABMS were extensively applied to establish the structures. The two bis-labdanic diterpenoids showed cytotoxic activity against human KB cells in vitro.

Key words

Alpinia calcarata. - Zingiberaceae - bis-labdanic diterpenoids - calcaratarin D - calcaratarin E - cytotoxic activity

References

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