Green tea polyphenols inhibit plasminogen activator inhibitor-1 expression and secretion in endothelial cells

Protective effects and molecular mechanisms of tea polyphenols on cardiovascular diseases

Aging is the most important factor contributing to cardiovascular diseases (CVDs), and the incidence and severity of cardiovascular events tend to increase with age. Currently, CVD is the leading cause of death in the global population. In-depth analysis of the mechanisms and interventions of cardiovascular aging and related diseases is an important basis for achieving healthy aging. Tea polyphenols (TPs) are the general term for the polyhydroxy compounds contained in tea leaves, whose main components are catechins, flavonoids, flavonols, anthocyanins, phenolic acids, condensed phenolic acids and polymeric phenols. Among them, catechins are the main components of TPs. In this article, we provide a detailed review of the classification and composition of teas, as well as an overview of the causes of aging-related CVDs. Then, we focus on ten aspects of the effects of TPs, including anti-hypertension, lipid-lowering effects, anti-oxidation, anti-inflammation, anti-proliferation, anti-angiogenesis, anti-atherosclerosis, recovery of endothelial function, anti-thrombosis, myocardial protective effect, to improve CVDs and the detailed molecular mechanisms.

Epicatechin influences primary hemostasis, coagulation and fibrinolysis

The different stages of hemostasis (i.e., primary hemostasis, coagulation and fibrinolysis) are involved in the early atherothrombosis steps. The aim of this study was to investigate the effect of epicatechin, a major flavonoid compound, on the hemostasis phenotype using clinically relevant in vitro global assays that mimic the complexity of the in vivo hemostasis systems. Plasma samples from 10 healthy volunteers were spiked with increasing concentrations of epicatechin (1 to 100 μM). Epicatechin effect on primary hemostasis, coagulation and fibrinolysis was assessed by measuring platelet aggregation using light transmission aggregometry, thrombin generation and clot lysis time (CLT), respectively. Epicatechin (100 μM) significantly decreased the maximal platelet aggregation induced by adenosine diphosphate (-39%), thrombin receptor activating peptide (-48%), epinephrine (-30%), and collagen (-30%). The endogenous thrombin potential was significantly reduced starting from 1 μM epicatechin (1332 ± 230 versus 1548 ± 241 nM min for control) (p < 0.01). Fibrinolysis was promoted by epicatechin, as indicated by CLT decrease by 16 and 33% with 10 and 100 μM epicatechin respectively, compared with control (1271 ± 775 s). These findings show that epicatechin reduces platelet function and leads to an anticoagulant and pro-fibrinolytic profile, providing new evidence of its interest for cardiovascular disease prevention.

Effects of a diet containing Brazilian propolis on lipopolysaccharide-induced increases in plasma plasminogen activator inhibitor-1 levels in mice

BACKGROUND

Brazilian propolis has many biological activities including the ability to help prevent thrombotic diseases, but this particular effect has not been proven. Plasma levels of plasminogen activator inhibitor-1 (PAI-1), an inhibitor of fibrinolysis, increase under inflammatory conditions such as infection, obesity and atherosclerosis and such elevated levels predispose individuals to a risk of developing thrombotic diseases.

AIM

This study aimed to determine the effects of a diet containing Brazilian propolis on lipopolysaccharide (LPS)-induced increases in plasma PAI-1 levels.

MATERIALS AND METHODS

Mice were fed with a diet containing 0.5% (w/w) Brazilian propolis for 8 weeks. Thereafter, the mice were subcutaneously injected with saline containing 0.015 mg/kg of LPS and sacrificed 4 h later.

RESULTS

Orally administered Brazilian propolis significantly suppressed the LPS-induced increase in PAI-1 antigen and its activity in mouse plasma.

CONCLUSION

This study indicated that Brazilian propolis contains natural products that can decrease thrombotic tendencies in mice.

Bisphenol A promotes X-linked inhibitor of apoptosis protein-dependent angiogenesis via G protein-coupled estrogen receptor pathway

Bisphenol A (BPA), one of the high-volume chemicals worldwide, has a core structure resembling that of natural estradiol. Recent evidence has demonstrated that exposure to BPA has a relationship with the risk of cancer. The objective of our study is to investigate the mechanisms underlying the pro-angiogenic effects of BPA. We demonstrated that BPA markedly induces endothelial cell proliferation, migration and tube formation by activating endothelial nitric oxide synthase. BPA-induced nitric oxide generation appeared to be associated with the X-linked inhibitor of apoptosis protein (XIAP), which competes with endothelial nitric oxide synthase for caveolin-1. BPA was shown to exert its pro-angiogenic effect by upregulating XIAP expression via G protein-coupled estrogen receptor (ER) activation but not via ERα or ERβ. Our data suggest that 100 nM BPA promote angiogenesis in a G protein-coupled ER-dependent genomic pathway, and provide a novel insight into the potential role of XIAP in mediating the pro-angiogenic effects of BPA in endothelial cells.

Unique vascular protective properties of natural products: supplements or future main-line drugs with significant anti-atherosclerotic potential?

Natural health products (NHP) which include minerals, vitamins and herbal remedies are not generally considered by medical practitioners as conventional medicines and as such are not frequently prescribed by health centre's as either main-line or supplemental treatments. In the field of cardiovascular medicine, studies have shown that typically, less than half of patients suffering from coronary syndromes chose to take any form of NHP supplement and these products are rarely recommended by their medical practitioner. Vascular/endothelial cell damage is a key instigator of coronary arterial plaque development which often culminates in thrombosis and myocardial infarction (MI). Current treatment for patients known to be at risk of primary or secondary (MI) includes lipid lowering statins, anti-clotting agents (e.g. tissue plasminogen activator; tPA) and drugs for stabilization of blood pressure such as beta-blockers. However, evidence has been building which suggests that components of at least several NHP (e.g. aged garlic extract (AGExt), resveratrol and green tea extracts (GTE)) may have significant vascular protective effects through reduction of oxidative stress, lowering of blood pressure, reduction in platelet aggregation, vasodilation and inhibition of abnormal angiogenesis. Therefore, in this review we will discuss in detail the potential of these substances (chosen on the basis of their potency and complimentarity) as anti-atherosclerotic agents and the justification for their consideration as main-line additional supplements or prescriptions.