ERK1/2 pathway is involved in the inhibitory effect of crocetin on angiotensin II-induced vascular smooth muscle cell proliferation

Crocetin: A Systematic Review

Crocetin is an aglycone of crocin naturally occurring in saffron and produced in biological systems by hydrolysis of crocin as a bioactive metabolite. It is known to exist in several medicinal plants, the desiccative ripe fruit of the cape jasmine belonging to the Rubiaceae family, and stigmas of the saffron plant of the Iridaceae family. According to modern pharmacological investigations, crocetin possesses cardioprotective, hepatoprotective, neuroprotective, antidepressant, antiviral, anticancer, atherosclerotic, antidiabetic, and memory-enhancing properties. Although poor bioavailability hinders therapeutic applications, derivatization and formulation preparation technologies have broadened the application prospects for crocetin. To promote the research and development of crocetin, we summarized the distribution, preparation and production, total synthesis and derivatization technology, pharmacological activity, pharmacokinetics, drug safety, drug formulations, and preparation 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

Vascular smooth muscle cell proliferation as a therapeutic target. Part 2: Natural products inhibiting proliferation

Many natural products have been so far tested regarding their potency to inhibit vascular smooth muscle cell proliferation, a process involved in atherosclerosis, pulmonary hypertension and restenosis. Compounds studied in vitro and in vivo as VSMC proliferation inhibitors include, for example indirubin-3'-monoxime, resveratrol, hyperoside, plumericin, pelargonidin, zerumbone and apamin. Moreover, taxol and rapamycin, the most prominent compounds applied in drug-eluting stents to counteract restenosis, are natural products. Numerous studies show that natural products have proven to yield effective inhibitors of vascular smooth muscle cell proliferation and ongoing research effort might result in the discovery of further clinically relevant compounds.

Inhibitory effects of 2,3,4',5-tetrahydroxystilbene-2-O-β-D-glucoside on angiotensin II-induced proliferation of vascular smooth muscle cells

OBJECTIVE

To investigate the effect of 2,3,4',5-tetrahydroxystilbene-2-O-β-D-glucoside (TSG), an active component extracted from the root of Polygonum multiflorum, on angiotensin II (Ang II)-induced proliferation of cultured rat vascular smooth muscle cells (VSMCs) and to identify the potential mechanism.

METHODS

Cell proliferation and cell cycle were determined by cell counting, 5-bromo-2'-deoxyuridine incorporation assay, proliferating cell nuclear antigen protein expression and flow cytometry. Levels of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2), mitogenic extracellular kinase 1/2 (MEK1/2) and Src in VSMCs were measured by Western blot. The expression of c-fos, c-jun and c-myc mRNA were measured by reverse transcription polymerase chain reaction (RT-PCR). Intracellular reactive oxygen species (ROS) was measured by fluorescence assay.

RESULTS

TSG significantly inhibited Ang II-induced VSMCs proliferation and arrested cells in the G /S checkpoint (P<0.05 or P<0.01). TSG decreased the levels of phosphorylated ERK1/2, MEK1/2 and Src in VSMCs (P<0.05 or P<0.01). TSG also suppressed c-fos, c-jun and c-myc mRNA expression <0.05 or P<0.01). In addition, the intracellular ROS was reduced by TSG (P<0.01).

CONCLUSIONS

TSG inhibited Ang II-induced VSMCs proliferation. Its antiproliferative effect might be associated with down-regulation of intracellular ROS, followed by the suppression of the Src-MEK1/2-ERK1/2 signal pathway, and hence, blocking cell cycle progression.

Fructus Gardenia (Gardenia jasminoides J. Ellis) phytochemistry, pharmacology of cardiovascular, and safety with the perspective of new drugs development

The phytochemistry, cardiovascular pharmacology, toxicology, side effect, and further development prospects of Gardenia jasminoides J. Ellis (GJE) and its main constituents crocins and iridoid glycosides were studied. Numerous studies have confirmed that crocins and iridoid glycosides had effects of antioxidation, anti-inflammatory, anti-atherosclerosis, anti-ischemic brain injuries, anti-platelet aggregation, anti-hyperglycemia, anti-hyperlipidemia, anti-hypertension, and so on. Some of them might be related to several attractive pharmacodynamic actions of GJE such as promoting endothelium growth, protecting neurons, and inducing their differentiation. Both of them make it possible for GJE to prevent and cure thromboembolism and cardiovascular diseases well. From our own basic pharmacological research of GJE extract on several rat models, it has been known that GJE extract markedly prolonged bleeding time and inhibited platelet aggregation and thrombosis. It has significant proliferation effect on both endothelial cells and endothelial progenitor cells as well. As the mechanisms of GJE on those diseases were discussed and summarized, questions about its genetoxicity and hepatotoxicity were also discussed during its safety study to make the foundation for long-term medication and clinical research in the near future.

Independent beta-arrestin2 and Gq/protein kinase Czeta pathways for ERK stimulated by angiotensin type 1A receptors in vascular smooth muscle cells converge on transactivation of the epidermal growth factor receptor

Recent studies in receptor-transfected cell lines have demonstrated that extracellular signal-regulated kinase (ERK) activation by angiotensin type 1A receptor and other G protein-coupled receptors can be mediated by both G protein-dependent and β-arrestin-dependent mechanisms. However, few studies have explored these mechanisms in primary cultured cells expressing endogenous levels of receptors. Accordingly, here we utilized the β-arrestin biased agonist for the angiotensin type 1A receptor, SII-angiotensin (SII), and RNA interference techniques to investigate angiotensin II (ANG)-activated β-arrestin-mediated mitogenic signaling pathways in rat vascular smooth muscle cells. Both ANG and SII induced DNA synthesis via the ERK activation cascade. Even though SII cannot induce calcium influx (G protein activation) after receptor stimulation, it does cause ERK activation, although less robustly than ANG. Activation by both ligands is diminished by depletion of β-arrestin2 by small interfering RNA, although the effect is more complete with SII. ERK activation at early time points but not later time points is strongly inhibited by those protein kinase C inhibitors that can block protein kinase Cζ. Moreover, ANG- and SII-mediated ERK activation require transactivation of the epidermal growth factor receptor via metalloprotease 2/9 and Src kinase. β-Arrestin2 facilitates ANG and SII stimulation of Src-mediated phosphorylation of Tyr-845 on the EGFR, a known site for Src phosphorylation. These studies delineate a convergent mechanism by which G protein-dependent and β-arrestin-dependent pathways can independently mediate ERK-dependent transactivation of the EGFR in vascular smooth muscle cells thus controlling cellular proliferative responses.

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.

Roscovitine inhibits ERK1/2 activation induced by angiotensin II in vascular smooth muscle cells

Roscovitine is a potent CDK inhibitor often used as a biological tool in cell-cycle studies, but its working mechanism and real targets in vascular smooth muscle cells (VSMCs) remain unclear. In this study, we observed that ERK1/2 phosphorylation induced by Ang II was abrogated by pretreating VSMCs with roscovitine for 15h. Pretreating VSMCs with roscovitine also inhibited Ang II-induced c-Jun expression and phosphorylation. We further demonstrated that roscovitine could suppress the DNA binding activity of c-Jun and activation of angiotensinogen promoter by Ang II. These results suggest that roscovitine represses Ang II-induced angiotensinogen expression by inhibiting activation of ERK1/2 and c-Jun.

Spectroscopic, stability and radical-scavenging properties of a novel pigment from gardenia

A novel pigment, named gardecin, has been isolated from gardenia fruits, together with another five known crocins. The pigment, which possessed a structure which is unique among crocins, was characterised using spectrometric techniques, particularly 1D and 2D NMR. The NMR assignments were based on data from (1)H NMR, (13)C NMR, DEPT, (1)H-(1)H COSY, NOESY, HMQC and HMBC measurements. The five known crocins were identified on the basis of MS, UV/visible and 1D NMR data. Chemical stability and antioxidant ability of gardecin in comparison with the other five crocins were studied. The stronger DPPH free radical-scavenging ability of gardecin compared, with the other crocins, was observed. Kinetic studies have shown that all crocins were unstable under various conditions, but surprisingly gardecin was fairly stable.

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

Crocetin, a carotenoid compound, was isolated from Gardenia jasminoids Ellis. Our recent study shows that crocetin inhibits angiotensin II-induced extracellular signal-regulated kinases 1/2 (ERK1/2) activation and subsequent proliferation in vascular smooth muscle cells (VSMCs). To further explore the mechanism involved, in the present study, we investigated the effect of Ca(2+) in the activation of ERK1/2 and whether Ca(2+) is involved in the suppression by crocetin of angiotensin II-induced ERK1/2 activation. Our findings showed that crocetin pretreatment partially attenuated both the intracellular Ca(2+) mobilization and the extracellular Ca(2+) influx induced by angiotensin II. Moreover, angiotensin II-induced ERK1/2 activation was completely abolished by acetoxymethyl ester of 1,2-bis(2-aminophenoxy)ethane-N,N,N ',N'-tetraacetic acid (BAPTA-AM), an intracellular Ca(2+) chelator, and partially inhibited by EGTA, an extracellular Ca(2+) chelator, or verapamil, an L-type Ca(2+) channel blocker. These findings suggest that Ca(2+) may play an important role in angiotensin II-induced ERK1/2 activation in VSMCs, and Ca(2+)-dependent pathway may be involved in the inhibitory effect by crocetin of angiotensin II-induced ERK1/2 activation.