Planta Med 2001; 67(4): 317-321
DOI: 10.1055/s-2001-14324
Original Paper
Pharmacology
© Georg Thieme Verlag Stuttgart · New York

Relaxing Effects of Ligstrum purpurascens Extract and Purified Acteoside in Rat Aortic Rings

Ivan Yuen Fan Wong1 , Yu Huang2,*, Zhen-Dan He1 , Chi-Wai Lau2 , Zhen-Yu Chen1
  • 1 Department of Biochemistry, Chinese University of Hong Kong, Hong Kong, China
  • 2 Department of Physiology, Chinese University of Hong Kong, Hong Kong, China
Further Information

Publication History

June 30, 2000

September 18, 2000

Publication Date:
31 December 2001 (online)

Abstract

The present study describes the effects of an extract obtained from the leaves of Ligstrum purpurascens and acteoside purified from the extract on the contractile response to various agonists in rat isolated aortic rings. L. purpurascens extract relaxed 9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F (U46619)-preconstricted rings in a concentration-dependent manner (IC50: 0.14 ± 0.01 mg/ml with endothelium and 0.16 ± 0.01 mg/ml without endothelium). The extract also reduced contraction induced by 35 mM K+ or by 1 μM phorbol 12,13-diacetate (PDA) in endothelium-intact rings. The extract (0.1 - 0.3 mg/ml) reduced the concentration-response to U46619 in normal Krebs solution or to CaCl2 in 35 mM K+-containing solution. Acteoside accounts for 2.05 % of total L. purpurascens extract in weight. Acteoside induced relaxation of rings preconstricted by U46619 (IC50: 0.22 ± 0.01 mg/ml) but it caused an increase in 35 mM K+-induced tone. Removal of endothelium enhanced the relaxing effect of acteoside. Besides, pretreatment with acteoside inhibited endothelium/nitric oxide-mediated relaxation induced by acetylcholine. These results indicate that acteoside is unlikely the major ingredient responsible for the vasodilator effect of L. purpurascens extract. The extract relaxed the preconstricted aortic rings probably through multiple mechanisms by acting on smooth muscle cells. The inhibitory effect on endothelial nitric oxide-mediated relaxation suggests that acteoside could also act on the endothelial cells to reduce nitric oxide release.

References

Yu Huang, Ph.D.

Department of Physiology

Faculty of Medicine

Chinese University of Hong Kong

Hong Kong

People's Republic of China

Email: yu-huang@cuhk.edu.hk

Fax: +852-26035022

Phone: +852-26096787