Dicentrine, a natural vascular α1‐adrenoceptor antagonist, isolated from Lindera megaphylla

1 The pharmacological activity of dicentrine, isolated from Lindera megaphylla, was determind in rat isolated thoracic aorta, guinea‐pig isolated trachea and human platelet‐rich plasma. 2 Dicentrine was found to be a potent α1‐adrenoceptor blocking agent in rat thoracic aorta as revealed by its comp...

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Published in:British journal of pharmacology 1991-11, Vol.104 (3), p.651-656
Main Authors: Teng, Che‐Ming, Yu, Sheu‐Meei, Ko, Feng‐Nien, Chen, Chien‐Chih, Huang, Yu‐Ling, Huang, Tur‐Fu
Format: Article
Language:English
Subjects:
Biological and medical sciences
Cardiovascular system
dicentrine
Lindera megaphylla
Medical sciences
Pharmacology. Drug treatments
prazosin
rat thoracic aorta
vascular smooth muscle
Vasodilator agents. Cerebral vasodilators
α1‐Adrenoceptor antagonist
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Summary:1 The pharmacological activity of dicentrine, isolated from Lindera megaphylla, was determind in rat isolated thoracic aorta, guinea‐pig isolated trachea and human platelet‐rich plasma. 2 Dicentrine was found to be a potent α1‐adrenoceptor blocking agent in rat thoracic aorta as revealed by its competitive antagonism of noradrenaline‐ (pA2 = 8.19 ± 0.09) or phenylephrine (pA2 = 9.01 ± 0.10)‐induced vasoconstriction. These effects still persisted in denuded aorta. It was less potent than prazosin (pA2 = 10.60 ± 0.10), but was more potent than phentolamine (pA2 = 7.53 ±0.10) or yohimbine (pA2 = 6.20 ± 0.05). 3 Inositol monophosphate formation induced by noradrenaline (3 μm) in rat thoracic aorta was suppressed by dicentrine (3–10 μm) and prazosin (3 μm). 4 A high concentration of dicentrine (30 μm) did not affect the aortic contraction induced by the thromboxane receptor agonist U‐46619 (1 μm), angiotensin II (1 μm), high potassium (60 mm) or carbachol (3 μm). 5 Contraction of guinea‐pig trachea caused by histamine or carbachol was slightly inhibited by dicentrine (30 μm), while β‐adrenoceptor relaxation to isoprenaline in trachea was not affected. 6 Aggregation in human platelet‐rich plasma induced by adrenaline (10 μm) was blocked by yohimbine (5 μm). A high concentration of dicentrine (> 30 μm) caused slight inhibition of aggregation, the release reaction and thromboxane formation. Complete blockade was obtained with 150 μm dicentrine. 7 It is concluded that dicentrine is a potent, selective α1‐adrenoceptor antagonist in vascular smooth muscle.
ISSN:0007-1188
1476-5381
DOI:10.1111/j.1476-5381.1991.tb12484.x