A new dimeric phenylpropanoid and cytotoxic norditerpene constituents from Podocarpus nakaii

Abstract

A new dimeric phenylpropanoid namely podonaka A (1), along with the 13 known compounds including diterpenes (2 and 3), norditerpenes (4 and 5), benzenoids (6–10), steroids (11 and 12), chalcone (13), and megastigmane (14), was isolated from the EtOH extract of Podocarpus nakaii Hayata. The structure of 1 was elucidated on the basis of spectroscopic analysis including 1D and 2D NMR and MS techniques. Biological evaluation showed that norditerpenes, inumakilactone B (4), and podolactone E (5) have potent cytotoxic activities against Daoy, WiDr, KB, and HeLa tumor cell lines. Moreover, low dosage of 5 may induce early apoptosis in KB cells before 12 h.

Keywords:

• Podocarpus nakaii
• podonaka A
• norditerpene
• cytotoxicity
• apoptosis

Acknowledgements

The grants from National Science Council (NSC 93-2320-B-077-007) and National Research Institute of Chinese Medicine, Taiwan (NRICM-96-DHM-02) are gratefully acknowledged. The authors also like to thank NSC Northern MS Instrumental Center in the National Chin-Hua University for the measurement of mass spectra.