Effects of Daidzein Sulfates on Blood Pressure and Artery of Rats

Effect of soy isoflavone supplementation on blood pressure: a meta-analysis of randomized controlled trials

BACKGROUND

Previous experimental studies have suggested that the consumption of soy isoflavones may have a potential impact on lowering blood pressure. Nevertheless, epidemiological studies have presented conflicting outcomes concerning the correlation between soy isoflavone consumption and blood pressure levels. Consequently, a comprehensive meta-analysis of all eligible randomized controlled trials (RCTs) was conducted to explore the influence of soy isoflavones on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults.

METHODS

A thorough search of PubMed, Embase, and the Cochrane Library for relevant literature up to April 30, 2023 was conducted. RCTs involving adults that compared soy isoflavone supplementation with a placebo (the same matrix devoid of soy isoflavone) were included. The combined effect size was presented as the weighted mean difference (WMD) along with 95% confidence interval (CI), employing a fixed-effects model.

RESULTS

Our meta-analysis included a total of 24 studies involving 1945 participants. The results revealed a significant reduction in both SBP and DBP with soy isoflavone supplementation. Subgroup analyses suggested more pronounced reductions in SBP and DBP for interventions lasting ≥6 months, in individuals receiving mixed-type soy isoflavone, and among patients with metabolic syndrome or prehypertension. However, we did not detect significant nonlinear associations between supplementation dosage and intervention duration concerning both SBP and DBP. The overall quality of evidence was deemed moderate.

CONCLUSIONS

The current meta-analysis revealed that supplementation with soy isoflavones alone effectively reduces blood pressure. Additional high-quality studies are required to investigate the efficacy of blood pressure reduction through supplementation with an optimal quantity and proportion of soy isoflavone.

Unveiling the Pharmacological and Nanotechnological Facets of Daidzein: Present State-of-the-Art and Future Perspectives

Herbal drugs have been attracting much scientific interest in the last few decades and nowadays, phytoconstituents-based research is in progress to disclose their unidentified medicinal potential. Daidzein (DAI) is the natural phytoestrogen isoflavone derived primarily from leguminous plants, such as the soybean and mung bean, and its IUPAC name is 4',7-dihydroxyisoflavone. This compound has received great attention as a fascinating pharmacophore with remarkable potential for the therapeutic management of several diseases. Certain pharmacokinetic properties of DAI such as less aqueous solubility, low permeability, and poor bioavailability are major obstacles restricting the therapeutic applications. In this review, distinctive physicochemical characteristics and pharmacokinetics of DAI has been elucidated. The pharmacological applications in treatment of several disorders like oxidative stress, cancer, obesity, cardiovascular, neuroprotective, diabetes, ovariectomy, anxiety, and inflammation with their mechanism of action are explained. Furthermore, this review article comprehensively focuses to provide up-to-date information about nanotechnology-based formulations which have been investigated for DAI in preceding years which includes polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carrier, polymer-lipid nanoparticles, nanocomplexes, polymeric micelles, nanoemulsion, nanosuspension, liposomes, and self-microemulsifying drug delivery systems.

Tissue Distribution of Orally Administered Prenylated Isoflavones, Glyceollins, in Sprague-Dawley Rats

Apart from the physiological effects of glyceollins, information regarding their tissue distribution is scarce in the literature. Thus, the aim of this study is to clarify the distribution of glyceollins in rat organs. Glyceollins I and III were orally administered to Sprague-Dawley rats (1.0 mg/kg) with daidzein as control, and their accumulations in organs were investigated by liquid chromatography-time-of-flight/mass spectrometry (LC-TOF/MS). Glyceollins accumulated in intact and conjugated forms in circulatory organs with a Tmax of 0.5 h, in the following order of descending preference: liver, kidney, heart, lung, soleus muscle, and abdominal aorta. The accumulation of hydrophobic glyceollin I was more than 1.5 times higher than that of III. In contrast, daidzein and hydroxy equol were detected only in the liver and kidneys at lower concentrations (1/100 times) than those of glyceollins. In conclusion, prenylated isoflavones, glyceollins, were preferentially distributed in circulatory organs as intact, sulfated, or glucuronidated forms up to 6 h after the intake.

The Vascular Effects of Isolated Isoflavones-A Focus on the Determinants of Blood Pressure Regulation

Isoflavones are phytoestrogen compounds with important biological activities, including improvement of cardiovascular health. This activity is most evident in populations with a high isoflavone dietary intake, essentially from soybean-based products. The major isoflavones known to display the most important cardiovascular effects are genistein, daidzein, glycitein, formononetin, and biochanin A, although the closely related metabolite equol is also relevant. Most clinical studies have been focused on the impact of dietary intake or supplementation with mixtures of compounds, with only a few addressing the effect of isolated compounds. This paper reviews the main actions of isolated isoflavones on the vasculature, with particular focus given to their effect on the determinants of blood pressure regulation. Isoflavones exert vasorelaxation due to a multitude of pathways in different vascular beds. They can act in the endothelium to potentiate the release of NO and endothelium-derived hyperpolarization factors. In the vascular smooth muscle, isoflavones modulate calcium and potassium channels, leading to hyperpolarization and relaxation. Some of these effects are influenced by the binding of isoflavones to estrogen receptors and to the inhibition of specific kinase enzymes. The vasorelaxation effects of isoflavones are mostly obtained with plasma concentrations in the micromolar range, which are only attained through supplementation. This paper highlights isolated isoflavones as potentially suitable alternatives to soy-based foodstuffs and supplements and which could enlarge the current therapeutic arsenal. Nonetheless, more studies are needed to better establish their safety profile and elect the most useful applications.

Two flavonoid metabolites, 3,4-dihydroxyphenylacetic acid and 4-methylcatechol, relax arteries ex vivo and decrease blood pressure in vivo

SCOPE

The flavonoid quercetin reduces arterial blood pressure in animals and humans but the mechanisms remains elusive. The aim of this study was to test the activity of flavonoid microbial metabolites, which can participate on the final vasorelaxant effect.

METHODS AND RESULTS

Both ex vivo (isolated rat thoracic aorta and mesenteric artery) and in vivo (normotensive and spontaneously hypertensive rats) approaches were used in this study. 4-methylcatechol and 3,4-dihydroxyphenylacetic acid (DHPA) had greater vasorelaxant effects on mesenteric artery than 3-(3-hydroxyphenyl)propionic acid, the previously reported metabolite with vasorelaxant effect. In vivo testing confirmed their blood pressure decreasing effect given both as bolus and slow infusion. Their mechanism at molecular level was different.

CONCLUSIONS

This study is the first to show that flavonoid metabolites DHPA and 4-methylcatechol decrease arterial blood pressure and hence a mixture of microbial metabolites formed in the gastrointestinal tract may be responsible for or contribute to the effect of orally ingested quercetin.

The intracellular metabolism of isoflavones in endothelial cells

Data from epidemiological and human intervention studies have highlighted potential cardiovascular benefits of soy isoflavone-containing foods. In humans, genistein and daidzein are extensively metabolized after absorption into glucuronides and sulfate metabolites. However, limited data exist on isoflavone cellular metabolism, in particular in endothelial cells. We investigated the uptake and cellular metabolism of genistein, daidzein and its major in vivo microbial metabolite, equol, in human endothelial (HUVEC), liver (HepG2) and intestinal epithelial cells (Caco-2 monolayer). Our results indicate that genistein and daidzein are taken up by endothelial cells, and metabolized into methoxy-genistein-glucuronides, methoxy-genistein-sulfates and methoxy-daidzein-glucuronides. In contrast, equol was taken up but not metabolized. In HepG2 and Caco-2 cells, glucuronide and sulfate conjugates of genistein and daidzein and a sulfate conjugate of equol were formed. Our findings suggest that endothelial cell metabolism needs to be taken into account when investigating the cardioprotective mechanisms of action of isoflavones.

An optimal initial tension for rat basilar artery in wire myography

AIMS

The aim of the present study was to determine the optimal initial tension for the rat basilar artery when using wire myography.

METHODS

Rat basilar arteries were mounted in myograph baths. A normalization procedure was performed. K(+)-rich (60mM) buffer solution-induced tension was measured in different initial tensions.

RESULTS

The initial tension of the basilar artery increased from 0.47 to 2.68mN/mm. Contractile tension was also elevated along with the initial tension. When the initial tension reached 1.63mN/mm, K(+)-induced contractile tension of basilar artery achieved its maximum. Thereafter, contractile tension declined as initial tension increased. The duration of equilibration time did not affect K(+)-induced contractile tension.

CONCLUSION

The optimal initial tension is 1.63±0.01mN/mm in rat basilar arteries when using wire myography.

Paeonol induces vasodilatation in rat mesenteric artery via inhibiting extracellular Ca²⁺ influx and intracellular Ca²⁺ release

OBJECTIVE

To investigate the vasodilative effect of paeonol in rat mesenteric artery and the mechanisms responsible for it.

METHODS

Rats were anaesthetized and sacrificed. The superior mesenteric artery was removed, dissected free of adherent tissue and cut into 2.0 mm long cylindrical segments. Isometric tension of artery rings was recorded by a myograph system in vitro. Concentration-relaxation curves of paeonol (17.8 μ mol/L to 3.16 mmol/L) were recorded on artery rings precontracted by potassium chloride (KCl) and concentration-contraction curves of KCl, 5-hydroxytryptamine (5-HT), noradrenaline (NA) or calcium chloride (CaCl2) were recorded in the presence of paeonol (10(-4.5), 10(-3.8), 10(-3.5) mol/L) respectively. And also, concentration-relaxation curves of paeonol were recorded in the presence of different potassium channel inhibitors and propranolol on rings precontracted with KCl respectively. To investigate the role of intracellular Ca(2+) release from Ca(2+) store, the contraction induced by NA (100 μ mol/L) and CaCl2 (2 mmol/L) in Ca(2+) free medium was observed in the presence of paeonol respectively.

RESULTS

Paeonol relaxed artery rings precontracted by KCl in a concentration-dependent manner and the vasodilatation effect was not affected by endothelium denudation. Paeonol significant decreased the maximum contractions (Emax) induced by KCl, CaCl2, NA and 5-HT, as well as Emax induced by NA and CaCl2 in Ca(2+) -free medium, suggesting that paeonol dilated the artery via inhibiting the extracellular Ca(2+) influx mediated by voltage-dependent calcium channel, and receptor-mediated Ca(2+)-influx and release. Moreover, none of glibenclamide, tetraethylammonium, barium chlorded and propranolol affected the paeonol-induced vasodilatation, indicating that the vasodilatation was not contributed to ATP sensitive potassium channel, calcium-activated potassium channel, inwardly rectifying potassium channel, and β-adrenoceptor.

CONCLUSION

Paeonol induces non-endothelium dependent-vasodilatation in rat mesenteric artery via inhibiting voltage-dependent calcium channel-mediated extracellular Ca(2+) influx and receptor-mediated Ca(2+) influx and release.

Metabolism and disposition of isoflavone conjugated metabolites in humans after ingestion of kinako

Isoflavone aglycones daidzein (Dein) and genistein (Gein) are present primarily as glucuronides and sulfates in human plasma; however, very little is known about the plasma pharmacokinetics of isoflavone conjugates after soy ingestion. The aim of this study was to investigate metabolism and disposition of the isoflavone conjugated metabolites glucuronide or sulfate or both after ingestion of kinako (baked soybean flour) by 10 volunteers. The quantifications of 16 metabolites in plasma and urine were performed by our previously reported high-performance liquid chromatography-UV-diode-array detector method. Plasma concentrations of total Dein and Gein metabolites reached maximal values of 0.64 ± 0.18 μM at 4.7 ± 2.5 h and 1.58 ± 0.55 μM at 5.4 ± 2.1 h, respectively. The area under the curve from 0 to 48 h demonstrated that daidzein-7-glucuronide-4'-sulfate (D-7G-4'S) (53.3%) was a major metabolite of Dein and that genistein-7-glucuronide-4'-sulfate (G-7G-4'S) (54.0%) and genistein-4',7-diglucuronide (G-4',7-diG) (26.6%) were major metabolites of Gein in plasma. The compositions of isoflavone metabolites in urine and plasma were greatly different. Approximately half of the 48-h urinary excretion of total Dein metabolites consisted of daidzein-7-glucuronide. The total amounts of genistein-7-glucuronide and genistein-4'-glucuronide were half the total amount of the urinary Gein metabolites. Excretion into urine of D-7G-4'S and G-7G-4'S accounted for only 16% each of the total Dein and Gein metabolites, respectively. The plasma and urine profiles of 16 metabolites of Dein and Gein demonstrate the involvement of desulfation and deglucuronidation of the conjugated metabolites D-7G-4'S, G-7G-4'S, and G-4',7-diG in the process of renal excretion.