Inhibitory effects of rutin on the endothelial protein C receptor shedding in vitro and in vivo

Pleiotropic actions of factor Xa inhibition in cardiovascular prevention: mechanistic insights and implications for anti-thrombotic treatment

Atherosclerosis is a chronic inflammatory disease in which atherothrombotic complications lead to cardiovascular morbidity and mortality. At advanced stages, myocardial infarction, ischaemic stroke, and peripheral artery disease, including major adverse limb events, are caused either by acute occlusive atherothrombosis or by thromboembolism. Endothelial dysfunction, vascular smooth muscle cell activation, and vascular inflammation are essential in the development of acute cardiovascular events. Effects of the coagulation system on vascular biology extend beyond thrombosis. Under physiological conditions, coagulation proteases in blood are pivotal in maintaining haemostasis and vascular integrity. Under pathological conditions, including atherosclerosis, the same coagulation proteases (including factor Xa, factor VIIa, and thrombin) become drivers of atherothrombosis, working in concert with platelets and vessel wall components. While initially atherothrombosis was attributed primarily to platelets, recent advances indicate the critical role of fibrin clot and plasma coagulation factors. Mechanisms of atherothrombosis and hypercoagulability vary depending on plaque erosion or plaque rupture. In addition to contributing to thrombus formation, factor Xa and thrombin can affect endothelial dysfunction, oxidative stress, vascular smooth muscle cell function as well as immune cell activation and vascular inflammation. By these mechanisms, they promote atherosclerosis and contribute to plaque instability. In this review, we first discuss the postulated vasoprotective mechanisms of protease-activated receptor signalling induced by coagulation enzymes under physiological conditions. Next, we discuss preclinical studies linking coagulation with endothelial cell dysfunction, thromboinflammation, and atherogenesis. Understanding these mechanisms is pivotal for the introduction of novel strategies in cardiovascular prevention and therapy. We therefore translate these findings to clinical studies of direct oral anticoagulant drugs and discuss the potential relevance of dual pathway inhibition for atherothrombosis prevention and vascular protection.

Buckwheat phenolic metabolites in health and disease

Buckwheat (Fagopyrum esculentum Moench, F. tataricum Gaertner) groats and flour have been established globally as nutritional foods because of their high levels of proteins, polyphenols and minerals. In some regions, buckwheat herb is used as a functional food. In the present study, reports of in vitro studies, preclinical and clinical trials dealing with the effect of buckwheat and its metabolites were reviewed. There are numerous reports of potential health benefits of consuming buckwheat, which may be in the form of food, dietary supplements, home remedies or possibly pharmaceutical drugs; however, adverse effects, including those resulting from contamination, must be considered. There are reports of antioxidative activity of buckwheat, which contains high levels of rutin and quercetin. On the other hand, both cytotoxic and antigenotoxic effects have been shown. Reduction of hyperlipidaemia, reduction of blood pressure and improved weight regulation have been suggested. Consuming buckwheat may have a beneficial effect on diabetes, since lower postprandial blood glucose and insulin response have been reported. In addition, buckwheat metabolites, such as rutin, may have intrinsic protective effects in preserving insulin signalling. Rutin has also been suggested to have potential therapeutic applications for the treatment of Alzheimer’s disease. The literature indicates that buckwheat is safe to consume and may have various beneficial effects on human health.

Impact of Plant-Derived Flavonoids on Neurodegenerative Diseases

Neurodegenerative disorders have a common characteristic that is the involvement of different cell types, typically the reactivity of astrocytes and microglia, characterizing gliosis, which in turn contributes to the neuronal dysfunction and or death. Flavonoids are secondary metabolites of plant origin widely investigated at present and represent one of the most important and diversified among natural products phenolic groups. Several biological activities are attributed to this class of polyphenols, such as antitumor activity, antioxidant, antiviral, and anti-inflammatory, among others, which give significant pharmacological importance. Our group have observed that flavonoids derived from Brazilian plants Dimorphandra mollis Bent., Croton betulaster Müll. Arg., e Poincianella pyramidalis Tul., botanical synonymous Caesalpinia pyramidalis Tul. also elicit a broad spectrum of responses in astrocytes and neurons in culture as activation of astrocytes and microglia, astrocyte associated protection of neuronal progenitor cells, neuronal differentiation and neuritogenesis. It was observed the flavonoids also induced neuronal differentiation of mouse embryonic stem cells and human pluripotent stem cells. Moreover, with the objective of seeking preclinical pharmacological evidence of these molecules, in order to assess its future use in the treatment of neurodegenerative disorders, we have evaluated the effects of flavonoids in preclinical in vitro models of neuroinflammation associated with Parkinson's disease and glutamate toxicity associated with ischemia. In particular, our efforts have been directed to identify mechanisms involved in the changes in viability, morphology, and glial cell function induced by flavonoids in cultures of glial cells and neuronal cells alone or in interactions and clarify the relation with their neuroprotective and morphogetic effects.

Flavonoid metabolites reduce tumor necrosis factor-α secretion to a greater extent than their precursor compounds in human THP-1 monocytes

Scope

Flavonoids are generally studied in vitro, in isolation, and as unmetabolized precursor structures. However, in the habitual diet, multiple flavonoids are consumed together and found present in the circulation as complex mixtures of metabolites. Using a unique study design, we investigated the potential for singular or additive anti‐inflammatory effects of flavonoid metabolites relative to their precursor structures.

Methods and results

Six flavonoids, 14 flavonoid metabolites, and 29 combinations of flavonoids and their metabolites (0.1–10 μM) were screened for their ability to reduce LPS‐induced tumor necrosis factor‐α (TNF‐α) secretion in THP‐1 monocytes. One micromolar peonidin‐3‐glucoside, cyanidin‐3‐glucoside, and the metabolites isovanillic acid (IVA), IVA‐glucuronide, vanillic acid‐glucuronide, protocatechuic acid‐3‐sulfate, and benzoic acid‐sulfate significantly reduced TNF‐α secretion when in isolation, while there was no effect on TNF‐α mRNA expression. Four combinations of metabolites that included 4‐hydroxybenzoic acid (4HBA) and/or protocatechuic acid also significantly reduced TNF‐α secretion to a greater extent than the precursors or metabolites alone. The effects on LPS‐induced IL‐1β and IL‐10 secretion and mRNA expression were also examined. 4HBA significantly reduced IL‐1β secretion but none of the flavonoids or metabolites significantly modified IL‐10 secretion.

Conclusion

This study provides novel evidence suggesting flavonoid bioactivity results from cumulative or additive effects of circulating metabolites.

Proinflammatory Pathways: The Modulation by Flavonoids

Inflammation is a natural, carefully orchestrated response of the organism to tissue damage, involving various signaling systems and the recruitment of inflammatory cells. These cells are stimulated to release a myriad of mediators that amplify the inflammatory response and recruit additional cells. These mediators present numerous redundancies of functions, allowing a broad and effective inflammatory response, but simultaneously make the understanding of inflammation pathways much difficult. The extent of the inflammatory response is usually self-limited, although it depends on the balance between the pro- and anti-inflammatory signals. When that equilibrium is dislocated, a more widespread inflammatory response may take place. Flavonoids have been shown to be possible alternatives to the traditionally molecules used as anti-inflammatory agents. In fact, the biological activities of flavonoids include the modulation of the diverse phases of inflammatory processes, from the gene transcription and expression to the inhibition of the enzymatic activities and the scavenging of the reactive species. In the present review, the inflammatory network is widely revised and the flavonoids' broad spectrum of action in many of the analyzed inflammatory pathways is revised. This kind of integrated revision is original in the field, providing the reader the simultaneous comprehension of the inflammatory process and the potential beneficial activities of flavonoids.