Planta Med 2004; 70(8): 718-722
DOI: 10.1055/s-2004-827201
Original Paper
Pharmacology
© Georg Thieme Verlag KG Stuttgart · New York

Vasorelaxation by Amentoflavone Isolated from Selaginella tamariscina

Dae Gill Kang1 , Ming Hao Yin1 , Hyuncheol Oh2 , Dae Ho Lee3 , Ho Sub Lee1
  • 1Department of Herbal Resources, Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk, Republic of Korea
  • 2Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea
  • 3Department of Internal Medicine, Cheju National University Hospital, Jeju, Republic of Korea
Further Information

Publication History

Received: January 6, 2004

Accepted: March 21, 2004

Publication Date:
24 August 2004 (online)

Abstract

In the courses of in vitro screening for the vasorelaxant effect of the various extracts from medicinal plants, an ethyl acetate-soluble extract of Selaginella tamariscina was found to exhibit distinctive vasorelaxant activity. Further purifications of the extract as guided by in vitro vasorelaxant assay afforded an active biflavonoid, amentoflavone. Amentoflavone induced concentration-dependent relaxation of the phenylephrine-precontracted aorta, which disappeared by removal of functional endothelium. Pretreatment of the aortic tissues with N G-nitro-L-arginine methyl ester (L-NAME), methylene blue, or 1H-[1] [2] [4]-oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) inhibited the relaxation induced by amentoflavone. Amentoflavone-induced relaxations were also markedly attenuated by addition of tetraethylammonium (TEA) or verapamil. However, the relaxant effect of amentoflavone was not blocked by pretreatment with indomethacin, glibenclamide, atropine, or propranolol. Incubation of endothelium-intact aortic rings with amentoflavone increased the production of cGMP, but this effect was blocked by endothelium-denudation or pretreatment with L-NAME or ODQ. These results suggest that amentoflavone relaxes vascular smooth muscle via endothelium-dependent nitric oxide-cGMP signaling, with possible involvement of non-specific K+ and Ca2+ channels.

Abbreviations

EDRF:endothelium-derived relaxing factor

EDHF:endothelium-derived hyperpolarizing factor

NO:nitric oxide

cGMP:guanosine 3′,5′-cyclic monophosphate

DMSO:dimethyl sulfoxide

L-NAME:N G-nitro-L-arginine methyl ester

ODQ:1H-[1,2,4]-oxadiazole-[4,3-a]-quinoxalin-1-one

IBMX:3-isobutyl-1-methylxanthine

KCa:Ca2+-dependent K+ channel

KATP:adenosine triphosphate (ATP)-sensitive K+ channel

TEA:tetraethylammonium

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Ho-Sub Lee, OMD, PhD

Department of Herbal Resources

Professional Graduate School of Oriental Medicine

Wonkwang University

Iksan

Jeonbuk 570-749

Republic of Korea

Phone: +82-63-850-6841

Fax: +82-63-850-5195

Email: host@wonkwang.ac.kr