Involvement of Ca2+ in the inhibition by crocetin of angiotensin II-induced ERK1/2 activation in vascular smooth muscle cells

A comprehensive review on biological activities and toxicology of crocetin

Natural products with high pharmacological potential and low toxicity have been considered as the novel therapeutic agents. Crocetin is an active constituent of saffron (Crocus sativus L.) stigma, which in its free-acid form is insoluble in water and most organic solvents. Crocetin exhibits various health-promoting properties including anti-tumor, neuroprotective effects, anti-diabetics, anti-inflammatory, anti-hyperlipidemia, etc. These therapeutic effects can be achieved with different mechanisms such as improvement of oxygenation in hypoxic tissues, antioxidant effects, inhibition of pro-inflammatory mediators, anti-proliferative activity and stimulation of apoptosis in cancer cells. It is also worth considering that crocetin could be tolerated without major toxicity at therapeutic dosage in experimental models. In the present review, we discuss the biosynthesis, pharmacokinetic properties of crocetin and provide a comprehensive study on the biological activities and toxicity along with the mechanism of actions and clinical trials data of crocetin.

The Protective Role of Crocus Sativus L. (Saffron) Against Ischemia- Reperfusion Injury, Hyperlipidemia and Atherosclerosis: Nature Opposing Cardiovascular Diseases

Background:

Reactive oxygen species and reactive nitrogen species, which are collective-ly called reactive oxygen-nitrogen species, are inevitable by-products of cellular metabolic redox reac-tions, such as oxidative phosphorylation in the mitochondrial respiratory chain, phagocytosis, reac-tions of biotransformation of exogenous and endogenous substrate in endoplasmic reticulum, eico-sanoid synthesis, and redox reactions in the presence of metal with variable valence. Among medici-nal plants, there is growing interest in Crocus Sativus L. It is a perennial, stemless herb, belonging to Iridaceae family, cultivated in various countries such as Greece, Italy, Spain, Israel, Morocco, Tur-key, Iran, India, China, Egypt and Mexico.

Objective:

The present study aims to address the anti-toxicant role of Crocus Sativus L. in the case of cardiovascular disease and its role towards the cardioprotective role of Crocus Sativus L.

Materials and

Methods:

An electronic literature search was conducted by the two authors from 1993 to August 2017. Original articles and systematic reviews (with or without meta-analysis), as well as case reports were selected. Titles and abstracts of papers were screened by a third reviewer to deter-mine whether they met the eligibility criteria, and full texts of the selected articles were retrieved.

Results:

Our review has indicated that scientific literature confirms the role of Crocus Sativus L. as a cardiovascular-protective agent. The literature review showed that Saffron is a potent cardiovascular-protective agent with a plethora of applications ranging from ischemia-reperfusion injury, diabetes and hypertension to hyperlipidemia.

Conclusion:

Literature findings represented in current review herald promising results for using Crocus Sativus L. and/or its active constituents as a cardiovascular-protective agent and in particular, Crocus Sativus L. manifests beneficial results against ischemia-reperfusion injury, hypertension, hy-perlipidemia and diabetes

Tetrahydroxystilbene glucoside inhibits TNF-α-induced migration of vascular smooth muscle cells via suppression of vimentin

Vascular smooth muscle cell (VSMC) migration triggered by TNF-α is an important event that occurs during the development of atherosclerosis. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside (TSG) has been proven to exhibit significant anti-atherosclerotic activity. Herein we investigate the inhibitory effect of TSG on TNF-α-induced VSMC migration and explore the underlying mechanisms. TSG pretreatment markedly inhibited TNF-α-induced cell migration. The inhibition of vimentin redistribution and expression was involved in the inhibitory effect of TSG on VSMC migration. The suppression of vimentin expression by shRNA in VSMCs significantly inhibited TNF-α-induced cell migration. Furthermore, TSG inhibited the TNF-α-induced expression of TGFβ1 and TGFβR1, and phosphorylation of TGFβR1 and Smad2/3. TSG also suppressed the nuclear translocation of Smad4 induced by TNF-α. These results suggest that TSG inhibits VSMC migration induced by TNF-α through inhibiting vimentin rearrangement and expression. The interruption of TGFβ/Smad pathway appears to be responsible for the suppression of TSG on vimentin expression.

Anticancer Effect and Molecular Targets of Saffron Carotenoids

Saffron carotenoids, crocin and crocetin, have shown anticancer activity in various animal models of cancer and against different cancerous cell lines. The radical scavenging property and activation of antioxidant defense system are two well-known characteristics of these compounds. However, the results of the studies indicated other mechanisms could also be involved in this function. Insights into various molecular mechanisms of action for crocin and crocetin have been obtained in recent years. The results indicated that despite the structural similarity of crocin and crocetin, their anticancer effects may exert through different mechanisms. Particular interest concerns the ROS-dependent signaling pathways of crocetin. Saffron compounds are safe and may provide inexpensive therapy for treating cancer. They also have protective potential in targeting other disorders including diabetes, Alzheimer's and cardiovascular disease, cognitive deficits, ischemia-induced retinal damage, and many other diseases.

Pinocembrin inhibits angiotensin II-induced vasoconstriction via suppression of the increase of [Ca2+]i and ERK1/2 activation through blocking AT(1)R in the rat aorta

Pinocembrin (5,7-dihydroxyflavanone) is one of the primary flavonoids in propolis. Angiotensin II (AngII) is a biologically active peptide that induces vasoconstriction via the activation of the angiotensin type 1 receptor (AT1R). In the present study, we investigated the vasorelaxant effect of pinocembrin on AngII-induced vasoconstriction and the molecular mechanism of action. Pinocembrin was observed to inhibit AngII-induced vasoconstriction in rat aortic rings with either intact or denuded endothelium. In endothelium-denuded tissues, pinocembrin (pD́'2pD2(') 4.28±0.15) counteracted the contractions evoked by cumulative concentrations of AngII. In a docking model, pinocembrin showed effective binding at the active site of AT1R. Pinocembrin was shown to inhibit both AngII-induced Ca(2+) release from internal stores and Ca(2+) influx. Moreover, the increase in the phosphorylation of extracellular signal-regulated kinase (ERK1/2) and myosin light chain 2 (MLC2) induced by AngII was blocked by pinocembrin. These results demonstrate that pinocembrin inhibits AngII-induced rat aortic ring contraction, and these inhibitory effects may be related to the reduction of the AngII-induced increase in [Ca(2+)]i and ERK1/2 activation via blocking AT1R.

2,3,4',5-tetrahydroxystilbene-2-O-β-D-glucoside inhibits proliferation of vascular smooth muscle cells: involvement of NO/cGMP/PKG pathway

The proliferation of vascular smooth muscle cells (VSMCs) induced by injury to the intima of arteries is an important etiologic factor in vascular proliferative disorders such as atherosclerosis and restenosis. 2,3,4',5-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG), an active component extracted from Polygonum multiflorum, has been found to have an antiatherosclerotic effect. The aim of this study was to investigate the effects of TSG on platelet derived growth factor (PDGF)-BB induced VSMCs proliferation and to explore the possible mechanisms of such effects. Pretreatment of VSMCs with TSG significantly inhibited PDGF-BB-induced cell proliferation in a concentration-dependent but not time-dependent manner. In addition, flow cytometry analysis of the DNA content revealed blocking of the PDGF-BB-inducible cell cycle progression by TSG. On the contrary, an inhibitory effect of TSG on VSMCs proliferation and expression of cell cycle regulators were markedly attenuated by addition of an nitric oxide (NO) synthase inhibitor, a soluble guanylate cyclase inhibitor and a cyclic GMP (cGMP)-dependent protein kinase (PKG) inhibitor: N(G)-nitro-L-arginine methyl ester (L-NAME), 1H-[1,2,4] oxadiazolo [4,3-α] quinoxalin-1-one (ODQ) and KT5823, respectively. It was also demonstrated that TSG enhanced NO and cGMP formation through up-regulating endothelial NO synthase expression in VSMCs. The findings indicate that TSG inhibited VSMCs proliferation induced by PDGF-BB may involve the NO/cGMP/PKG signal pathway.

Crocetin protects against cardiac hypertrophy by blocking MEK-ERK1/2 signalling pathway

Oxidative stress plays a critical role in the progression of pathological cardiac hypertrophy and heart failure. Because crocetin represses oxidative stress in vitro and in vivo, we have suggested that crocetin would repress cardiac hypertrophy by targeting oxidative stress-dependent signalling. We tested this hypothesis using primary cultured cardiac myocytes and fibroblasts and one well-established animal model of cardiac hypertrophy. The results showed that crocetin (1–10 μM) dose-dependently blocked cardiac hypertrophy induced by angiogensin II (Ang II; 1 μM) in vitro. Our data further revealed that crocetin (50 mg/kg/day) both prevented and reversed cardiac hypertrophy induced by aortic banding (AB), as assessed by heart weight/body weight and lung weight/body weight ratios, echocardio-graphic parameters and gene expression of hypertrophic markers. The inhibitory effect of crocetin on cardiac hypertrophy is mediated by blocking the reactive oxygen species (ROS)-dependent mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase-1/2 (MEK/ERK1/2) pathway and GATA binding protein 4 (GATA-4) activation. Further investigation demonstrated that crocetin inhibited inflammation by blocking nuclear factor kappa B (NF-κB) signalling and attenuated fibrosis and collagen synthesis by abrogating MEK-ERK1/2 signalling. Overall, our results indicate that crocetin, which is a potentially safe and inexpensive therapy for clinical use, has protective potential in targeting cardiac hypertrophy and fibrosis by suppression of ROS-dependent signalling pathways.

Involvement of Ca2+ in the inhibition by crocetin of platelet activity and thrombosis formation

Crocetin, a unique carotenoid with potent antioxidative and anti-inflammatory activities, is a major ingredient of saffron used as an important spice and food colorant in various parts of the world. In the present study, the effects of crocetin on platelet activity and thrombosis formation were systematically investigated. Crocetin showed a dose-dependent inhibition of platelet aggregation induced by ADP, collagen, but not by arachidonic acid (AA). Crocetin significantly attenuated dense granule release, while neither platelets adhesion to collagen nor cyclic AMP level was altered by crocetin. Pretreatment with crocetin was confirmed to partially inhibit Ca (2+) mobilization via reducing both intracellular Ca (2+) release and extracellular Ca (2+) influx. Besides that, crocetin prolonged the occlusive time in electrical stimulation-induced carotid arterial thrombosis. These findings suggest that the favorable impacts of crocetin on platelet activity and thrombosis formation may be related to the inhibition of Ca (2+) elevation in stimulated platelets.