Research articleFormononetin, an isoflavone, relaxes rat isolated aorta through endothelium-dependent and endothelium-independent pathways
Introduction
Cardiovascular disease is a major cause of death or disability in many developed countries. Smoking, high cholesterol and obesity are well-known risk factors of cardiovascular disease, and they are associated with decreased availability of endothelial cells-derived nitric oxide (NO) in the cardiovascular system. Isoflavones are phytoestrogens that have been gathering an increased interest in the areas of clinical nutrition and diseases prevention [1], [2] especially for postmenopausal women in view of the some unfavorable consequences/potential risks (e.g., stroke and coronary heart disease) associated with the use of estrogen-like substances (so-called hormone replacement therapy) [3]. Thus, there is an urgent need for estrogen alternatives (e.g., phytoestrogens) for providing beneficial cardiovascular effects. Recent studies provided evidence that isoflavones can restore endothelial dysfunction via an increase of NO generation [4], [5], [6], [7], [8].
Formononetin [7-hydroxy-3(4-methoxypheny)chromone (C16H12O4) (Fig. 1)] is an isoflavonoid found abundantly in traditional Chinese medicine Astragalus mongholicus Bunge (known as Huang Qi in China and Ougi in Japan) and Trifolium pratense L. (red clover). They belong to the family Leguminosae. The extract of these herbs has been used clinically to treat different diseases including cardiovascular diseases in China for a long time [9], [10], [11]. In addition, formononetin possesses hypolipidemic properties [12], mammary gland proliferation function [13] and antioxidative and estrogenic effects [14]. The extract of Astragalus membraneaceus has also been demonstrated to possess endothelium-dependent and endothelium-independent vasodilatory effects [15], [16], [17], and daidzein, a metabolite of formononetin formed in vivo, can relax rats' aorta and pulmonary artery [18], [19], [20]. However, the underlying mechanisms of formononetin involved (especially its effects on ion channels modulation) in eliciting vasorelaxation has not been elucidated in details. Thus, in this study, we tested the hypothesis that formononetin-induced vascular relaxation involved the openings of K+ channels of the vascular smooth muscle. More importantly, as formononetin is a phytoestrogen which shares a chemical structure similar to estrogen/progesterone (Fig. 1), the participation of estrogen and progesterone receptors in mediating the vascular responses will be elucidated.
Section snippets
Drugs and chemicals
Formononetin was purchased from Acros Organics (Belgium) and the stock solution (100 mM) of formononetin was prepared in dimethyl sulphoxide and stored at −20°C until use. Genistein, daidzein, biochanin A, phenylephrine hydrochloride, acetylcholine hydrochloride (ACh), neostigmine hydrobromide, indomethacin, Nω-nitro-l-arginine methyl ester (L-NAME), methylene blue (MB), proporanolol and prazosin were obtained from Sigma-Aldrich (St. Louis, MO, USA). 1400W; ICI 182,780; mifepristone;
Relaxation of rat aorta by formononetin
After the phenylephrine (1 μM)-induced contraction reached a sustained/steady-state condition, cumulative application of formononetin (0.1–100 μM) caused a concentration-dependent relaxation and a maximum relaxation of 98.50±1.50 % was observed in endothelium-intact preparation. Other phytoestrogens (genistein, daidzein and biochanin A) were evaluated and compared. Similar to formononetin, cumulative administration of these compounds caused a concentration-dependant relaxation of
Discussion
The present study demonstrates, for the first time, that formononetin (a phytoestrogen) elicited a concentration-dependent relaxation of rat precontracted thoracic aortic rings through both endothelium-dependent and endothelium-independent mechanisms. Our results (using pharmacological/chemical and molecular biology approaches) illustrate that the endothelium-dependent component of formononetin-induced relaxation, similar to other NO/endothelium-related vasorelaxants, is associated with an
Acknowledgments
We are grateful to assistance provided by technicians of State Key Laboratory of Chinese Medicine and Molecular Pharmacology, Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University (Hong Kong SAR, PR China). This project was supported by a research grant of the “Shenzhen Virtual University Park,” Shenzhen Government (PR China), the Niche Area Research Grant of the Hong Kong Polytechnic University, Direct Grants for Research (The Chinese University of Hong Kong)
References (29)
- et al.
Dietary isoflavones: biological effects and relevance to human health
J Nutr
(1999) - et al.
Soy isoflavones enhance coronary vascular reactivity in atherosclerotic female macaques
Fertil Steril
(1997) - et al.
The effect of the phytoestrogen genistein on plasma nitric oxide concentrations, endothelin-1 levels and endothelium dependent vasodilation in postmenopausal women
Atherosclerosis
(2002) - et al.
Puerarin decreases serum total cholesterol and enhances thoracic aorta endothelial nitric oxide synthase expression in diet-induced hypercholesterolemic rats
Life Sci
(2006) - et al.
Analysis of nitrate, nitrite and [15N] nitrate in biological fluids
Anal Biochem
(1982) - et al.
Crocetin improves endothelium-dependent relaxation of thoracic aorta in hypercholesterolemic rabbit by increasing eNOS activity
Biochem Pharmacol
(2006) - et al.
Activation of iberiotoxin-sensitive, Ca2+-activated K+ channels of porcine isolated left anterior descending coronary artery by diosgenin
Eur J Pharmacol
(2004) - et al.
Contribution of glibenclamide-sensitive, ATP-dependent K+ channel activation to acetophenone analogues-mediated in vitro pulmonary artery relaxation of rat
Life Sci
(2006) - et al.
Novel water-soluble dopamine-2 antagonist with anticholinesterase activity in gastrointestinal motor activity. Comparison with domperidone and neostigmine
Gastroenterology
(1990) - et al.
Whittle BJ, et al. 1400W is a slow, tight binding, and highly selective inhibitor of inducible nitric-oxide synthase in vitro and in vivo
J Biol Chem
(1997)
Clinical review 97: potential health benefits of dietary phytoestrogens: a review of the clinical, epidemiological, and mechanistic evidence
J Clin Endocrinol Metab
Hormone replacement therapy and cardiovascular disease: increased risks of venous thromboembolism and stroke, and no protection from coronary heart disease
J Intern Med
Oral administration of soy extract improves endothelial dysfunction in ovariectomized rats
Planta Med
Isolated soy protein improves endothelial function in postmenopausal hypercholesterolemic women
Eur J Clin Nutr
Cited by (79)
Conventional loose mineral with added red clover leaf (Trifolium pratense L.) reverses vasoconstriction associated with tall fescue toxicosis in steers
2023, Animal Feed Science and TechnologyCitation Excerpt :In addition to nutritional benefits, legumes contain biologically active isoflavones that have selective antimicrobial activity in the rumen pre-absorption, consequently improving growth performance in grazing cattle (Harlow et al., 2017a, 2020). Isoflavones have also been demonstrated to induce arterial vasodilation post-absorption, preventing and reversing fescue toxicosis (Wu et al., 2010; Aiken et al., 2016). Several routes of legume supplementation have been successfully utilized to mitigate fescue toxicosis in ruminants including: overseeding clovers, stored forages, legume-based feeds, and by-products (e.g., soybean meal; soyhulls; Carter et al., 2010; Shappell et al., 2015; Harlow et al., 2021; Harlow et al., 2022).
Formononetin attenuates Aβ<inf>25-35</inf>-induced adhesion molecules in HBMECs via Nrf2 activation
2022, Brain Research BulletinComparison of the global metabolic responses to UV-B radiation between two medicinal Astragalus species: An integrated metabolomics strategy
2020, Environmental and Experimental BotanyBiochanin-A elicits relaxation in coronary artery of goat through different mechanisms
2020, Research in Veterinary ScienceProgesterone induces relaxation of human umbilical cord vascular smooth muscle cells through mPRα (PAQR7)
2018, Molecular and Cellular EndocrinologyCitation Excerpt :It is well established that estradiol-17β and progesterone exert rapid non-genomic actions on vascular endothelial cells to upregulate NO production and its release onto the adjacent VSMCs, resulting in their relaxation (Mendelsohn, 2002; Pang et al., 2015; Simoncini et al., 2004). However, a growing body of evidence suggests that these sex steroids can also cause rapid relaxation of arteries in an endothelial cell-independent manner (Wu et al., 2010). Progesterone has been shown to cause rapid relaxation of endothelium-denuded rat and rabbit artery rings (Cairrao et al., 2012; Glusa et al., 1997; Jiang et al., 1992; Li et al., 2001; Perusquia et al., 1996).