Inhibitory effects of emodin on the proliferation of cultured rat vascular smooth muscle cell-induced by angiotensin II

Emodin in atherosclerosis prevention: Pharmacological actions and therapeutic potential

Atherosclerotic plaque formation, destabilization and eventual rupture leads to the acute cardiovascular events including myocardial infarction and stroke. Emodin (PubChem CID#3220), (1,3,8-trihydroxy-6-methylanthracene-9,10-dione) is a pharmacologically bioactive constituent isolated from the traditional Chinese medicinal herb Radix rhizoma Rhei. This molecule has anti-oxidant, anti-inflammatory, anti-proliferative, anti-apoptotic and lipid-modulating effects. Experimental studies have demonstrated that emodin attenuates and stabilizes atherosclerotic plaques. In this mini-review, we provide a summary of the pharmacological actions of emodin in regulating vascular function and atherosclerosis, highlighting the therapeutic potential of this phytochemical in patients with cardiovascular disease.

Molecular Mechanisms of Action of Emodin: As an Anti-Cardiovascular Disease Drug

Emodin is a natural occurring anthraquinone derivative isolated from roots and barks of numerous plants, molds, and lichens. It is found to be an active ingredient in different Chinese herbs including Rheum palmatum and Polygonam multiflorum, and it is a pleiotropic molecule with diuretic, vasorelaxant, anti-bacterial, anti-viral, anti-ulcerogenic, anti-inflammatory, and anti-cancer effects. Moreover, emodin has also been shown to have a wide activity of anti-cardiovascular diseases. It is mainly involved in multiple molecular targets such as inflammatory, anti-apoptosis, anti-hypertrophy, anti-fibrosis, anti-oxidative damage, abnormal, and excessive proliferation of smooth muscle cells in cardiovascular diseases. As a new type of cardiovascular disease treatment drug, emodin has broad application prospects. However, a large amount of evidences detailing the effect of emodin on many signaling pathways and cellular functions in cardiovascular disease, the overall understanding of its mechanisms of action remains elusive. In addition, by describing the evidence of the effects of emodin in detail, the toxicity and poor oral bioavailability of mice have been continuously discovered. This review aims to describe a timely overview of emodin related to the treatment of cardiovascular disease. The emphasis is to summarize the pharmacological effects of emodin as an anti-cardiovascular drug, as well as the targets and its potential mechanisms. Furthermore, the treatment of emodin compared with conventional cardiovascular drugs or target inhibitors, the toxicity, pharmacokinetics and derivatives of emodin were discussed.

Nucleolin promotes Ang II‑induced phenotypic transformation of vascular smooth muscle cells via interaction with tropoelastin mRNA

The current study aimed to clarify the role of nucleolin in the phenotypic transformation of vascular smooth muscle cells (VSMCs) and to preliminarily explore its underlying mechanism. The spatial and temporal expression patterns of nucleolin, and the effects of angiotensin II (Ang II) on the expression of VSMC phenotypic transformation markers, α‑smooth muscle‑actin, calponin, smooth muscle protein 22α and osteopontin were investigated. The effects of nucleolin on VSMC phenotypic transformation and the expression of phenotypic transformation‑associated genes, tropoelastin, epiregulin and fibroblast growth factor 2 (b‑FGF), were determined. Protein‑RNA co‑immunoprecipitation was used to investigate the potential target genes regulated by the nucleolin in phenotypic transformation of VSMCs. Finally, the stability of tropoelastin mRNA and the effects of nucleolin on the expression of tropoelastin were assayed. The results revealed that Ang II significantly promoted the phenotypic transformation of VSMCs. The expression of nucleolin was gradually upregulated in VSMCs treated with Ang II at different concentrations for various durations. Ang II induced nucleolin translocation from the nucleus to cytoplasm. Additionally, Ang II significantly promoted the phenotypic transformation of VSMCs. Overexpression and silencing of nucleolin regulated the expressions of tropoelastin, epiregulin and b‑FGF. There was an interaction between tropoelastin mRNA and nucleolin protein, promoting the stability of tropoelastin mRNA and enhancing the expression of tropoelastin at the protein level. Upregulation of nucleolin had an important role in Ang II‑induced VSMC phenotypic transformation, and its underlying mechanism may be through interacting with tropoelastin mRNA, leading to its increased stability and protein expression. The findings provide a new perspective into the regulatory mechanism of VSMC phenotypic transformation.

Plant-Derived Products for Treatment of Vascular Intima Hyperplasia Selectively Inhibit Vascular Smooth Muscle Cell Functions

Natural products are used widely for preventing intimal hyperplasia (IH), a common cardiovascular disease. Four different cells initiate and progress IH, namely, vascular smooth muscle, adventitial and endothelial cells, and circulation or bone marrow-derived cells. Vascular smooth muscle cells (VSMCs) play a critical role in initiation and development of intimal thickening and formation of neointimal hyperplasia. In this review, we describe the different originating cells involved in vascular IH and emphasize the effect of different natural products on inhibiting abnormal cellular functions, such as VSMC proliferation and migration. We further present a classification for the different natural products like phenols, flavonoids, terpenes, and alkaloids that suppress VSMC growth. Abnormal VSMC physiology involves disturbance in MAPKs, PI3K/AKT, JAK-STAT, FAK, and NF-κB signal pathways. Most of the natural isolate studies have revealed G1/S phase of cell cycle arrest, decreased ROS production, induced cell apoptosis, restrained migration, and downregulated collagen deposition. It is necessary to screen optimal drugs from natural sources that preferentially inhibit VSMC rather than vascular endothelial cell growth to prevent early IH, restenosis following graft implantation, and atherosclerotic diseases.

Emodin as a selective proliferative inhibitor of vascular smooth muscle cells versus endothelial cells suppress arterial intima formation

A well-known natural anthraquinone "Emodin", has been proven to inhibit the proliferation of vascular smooth muscle cells (VSMCs). But the anti-proliferative effects of emodin on both VSMCs versus vascular endothelial cells (VECs) are still largely unknown. Herein, a comparative study for the evaluation of anti-proliferation effects of emodin on human VSMCs and VECs was designed. Various methodologies including MTS, EdU assay, FACS analysis, qRT-PCR and mitochondrial fluorescent probes were used for detecting cell viabilities, DNA synthesis rate, cell cycle, proliferation genes expression levels and mitochondrial activities, respectively. In addition, carotid arteries balloon injury was performed to evaluate the effects of emodin on intima hyperplasia (IH) and re-endothelialization. The emodin showed a dose-dependent (0.05 to 5 μM) inhibition of hVSMCs proliferation was quiet higher than hVECs in vitro. Conditioned culture media with a range of emodin concentrations (2.5, and 5 μM) reduced CDK1, Ki67, and E2F-1 gene expression, along with inhibition of mitochondrial activities in both hVSMCs and hVECs cells, while former remained highly sensitive. Emodin (10 mg/kg) was injected intraperitoneally for 2 weeks, and had obvious alleviation in an endothelial denudation induced-IH formation and limited interfere-endothelialization in injured arteries in vivo. Emodin preferentially inhibited hVSMCs proliferation but not the hVECs in vitro and had limited influence on the re-endothelialization of later in a rat artery endothelial denudation model. It is concluded that emodin will provide a promising approach for efficient prevention of blood vessel restenosis.

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.

Emodin Combined with Nanosilver Inhibited Sepsis by Anti-inflammatory Protection

Background: Emodin is the main active component of rhubarb, which has demonstrated many beneficial effects against inflammation. Nanosilver is an effective antimicrobial agent. The present study was designed to observe the effects of Emodin combined with silver nanoparticles (E/S) on sepsis protection and related mechanism.

Methods: E/S was prepared by loading different concentrations of Emodin on nanosilver and cytotoxicity of E/S were determined by suphorhodamine B assays. Anti-microbial activities of E/S were assayed by direct interaction with various common pathogens and anti-adhesive activites of E/S on leukocytes with endothelial cells were assayed by biochemical analysis. Next, inflammatory cell enumeration, inflammatory mediators in bronchoalveolar lavage fluid (BALF) and endothelial cell function were analyzed on a clinically relevant model of sepsis induced by cecal ligation and puncture (CLP) after E/S administration. The effects of E/S on NF-κB and p38 were also examined by western blot.

Results: E/S exhibited little cytotoxicity action on endothelial cells and significant inhibitory activities against all tested common microorganisms and adherence between leukocyte and endothelial cells. E/S induced anti-sepsis protection mainly mediated by inhibition of inflammatory cells infiltration, down-regulation of TNF-alpha, IL-8 and lactic dehydrogenase (LDH), and inhibition of NF-κB and p38 pathways in mice 24 h post-CLP.

Conclusion: Our data suggest that E/S has strong anti-sepsis effects, which was related with anti-inflammatory protection and thereby promote survival following sepsis challenge.

Influence of the Environmental Factors on the Accumulation of the Bioactive Ingredients in Chinese Rhubarb Products

To provide a basis for controlling the quality of rhubarb under artificial cultivation, the present work was designed to evaluate the contents of 14 active pharmaceutical ingredients (API) of rhubarb in major rhubarb production areas in China and analyze the correlations between the contents of API and such factors as species, geographic distribution and soil. The levels of fourteen API in rhubarb were measured using HPLC. The geographic distributions were collected using GPS and the nutrients in the soil were measured using the methods in the literature. The results showed that the levels of major API vary significantly among plants of different locations according to variance analysis. The species factor has few obvious effect on the overall properties of the rhubarb by the cluster analysis because of the two source species occurring in all divided three groups. However, Rheum tanguticum Maxim.ex Balf. is less effective at synthesizing and accumulating 9 API out of 14 than Rheum palmatum L. The correlation analysis and regression analysis also indicated that a lower latitude should be considered in the accumulation of API and a lower longitude should be considered to produce more compound anthraquinones. Lower levels of total P, rapidly available P and available molybdenum (Mo) and higher available K and available Zn in the soil were significantly correlated to accumulation of API in rhubarb. These results provide a basis for the clinical application and controlling the levels of the major API of rhubarb during artificial cultivation.

Emodin inhibits splenocyte proliferation and inflammation by modulating cytokine responses in a mouse model system

Emodin, an anthraquinone derivative, was investigated for potential anti-inflammatory and anti-proliferative effects in vitro. The potential to induce these outcomes was assessed using concanavalin A (ConA)-stimulated mouse splenocytes. Dose-response studies showed that emodin at 100 µM was not cytotoxic to naive cells, and that the same dose caused proliferation to be significantly reduced in ConA-stimulated cells. In addition, emodin significantly reduced ConA-induced nitric oxide (NO) production and the formation/release of TH1 (IL-2, IFNγ, TNFα) and TH17 (IL-6 and IL-17) cell cytokines, but induced those of TH2 (IL-4) and Treg (IL-10) cells. From the results, it is concluded that earlier-reported immunomodulatory effects imparted by emodin may have been attributable, in part, to anti-proliferative effects on lymphocytes, as well as a shift within the TH1/TH2 and TH17/Treg balance (towards TH2 and Treg). These findings, while providing evidence of mechanisms of emodin immunomodulation, are also potentially important for sparking studies that ultimately may result in the potential use of this agent in preventive and/or corrective strategies against autoimmune and other inflammatory diseases.

Rutaecarpine inhibits angiotensin II-induced proliferation in rat vascular smooth muscle cells

OBJECTIVE

To evaluate the effects and possible mechanisms of rutaecarpine on angiotensin II (Ang II)-induced proliferation in cultured rat vascular smooth muscle cells (VSMCs).

METHODS

VSMCs were isolated from Male Sprague-Dawley rat aorta, and cultured by enzymic dispersion method. Experiments were performed with cells from passages 3-8. The cultured VSMCs were randomly divided into control, model (Ang II 0.1 μmol/L), and rutaecarpine (0.3-3.0 μmol/L) groups. VMSC proliferation was induced by Ang II, and was evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and cell counting. To examine the mechanisms involved in anti-proliferative effects of rutaecarpine, nitric oxide (NO) levels and NO synthetase (NOS) activity were determined. Expressions of VSMC proliferation-related genes including endothelial nitric oxide synthase (eNOS), and c-myc hypertension related gene-1 (HRG-1) were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Rutaecarpine (0.3-3.0 μmol/L) inhibited Ang II-induced VSMC proliferation and the best effects were achieved at 3.0 μmol/L. The Ang II-induced decreases in cellular NO contents and NOS activities were antagonized by rutaecarpine (P <0.05). Ang II administration suppressed the expressions of eNOS and HRG-1, while increased c-myc expression (P <0.05). All these effects were attenuated by 3.0 μmol/L rutaecarpine (P <0.05).

CONCLUSION

Rutaecarpine is effective against Ang II-induced rat VSMC proliferation, and this effect is due, at least in part, to NO production and the modulation of VMSC proliferation-related gene expressions.

The effect of endothelial progenitor cells on angiotensin II-induced proliferation of cultured rat vascular smooth muscle cells

Previous studies have demonstrated that endothelial progenitor cells (EPCs) could delay the progress of vascular remodeling in blood vessel-proliferating diseases. The proliferation of vascular smooth muscle cells (VSMCs) is a pivotal factor in cardiovascular diseases. In this study, we investigated whether EPCs could inhibit the Angiotensin II (Ang II)-induced proliferation of VSMCs. The effect of early EPC-conditioned medium (E-EPC-CM), late EPCs-CM (L-EPC-CM), and HUVEC-CM on Ang II-induced proliferation of VSMCs was assessed by BrdU incorporation, total protein content, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, and flow cytometry. Reverse transcriptase-polymerase chain reaction and Western blot were performed to analyze the effect of different CMs on Ang II-induced phosphorylations of ERK, JNK, p38, and NF-κB subunit p65 and the expressions of c-myc and c-fos. E-EPC-CM, L-EPC-CM, and HUVEC-CM significantly inhibited the Ang II-induced DNA synthesis, total protein expression, cell survival, and cell cycle progress of VSMCs. Furthermore, E-EPC-CM significantly inhibited the Ang II-induced phosphorylation of ERK, JNK, p38, and p65 (nuclear translocation of p65) and the expressions of c-myc and c-fos. Taken together, these data suggested that EPCs may delay the progress of vascular remodeling in blood vessel-proliferating diseases by inhibiting Ang II-induced proliferation of VSMCs through inactivating MAPKs and NF-κB signaling pathways and by reducing the expressions of c-myc and c-fos.

Calcitonin gene-related peptide released from endothelial progenitor cells inhibits the proliferation of rat vascular smooth muscle cells induced by angiotensin II

We have recently demonstrated that endothelial progenitor cells (EPCs) inhibit AngII-induced proliferation of vascular smooth muscle cells (VSMCs) by inactivating MAPKs and NF-κB signaling pathway and reducing expression of oncogene c-myc and c-fos. The inhibitory effect of EPCs on VSMCs is associated with paracrine mechanism. However, the potential mechanism of EPCs on the regulation of AngII-induced proliferation of VSMCs was unknown. Calcitonin gene-related peptide (CGRP) could inhibit AngII-induced proliferation and transformation of VSMCs. However, it has not been known whether CGRP released from EPCs is a potential regulator in regulation of AngII-induced proliferation of VSMCs. Early endothelial progenitor cell-conditioned medium(E-EPC-CM) was pre-incubated with functional blocking antibodies against CGRP for 1 h or VSMCs was preteated with CGRP(837)(CGRP receptor antagonist) for 1 h before VSMCs were pretreated with CM for 30 min. DNA synthesis ability, total protein levels, cell survival, signal transduction, and expressions of c-myc and c-fos of VSMCs induced by AngII (10(-6)mol/l) were detected to assess the role of CGRP in AngII-induced proliferation of VSMCs. E-EPC-CM could significantly inhibit AngII-induced DNA synthesis ability, total protein levels, cell survival, phosphorylation of ERK, JNK, p38, p65, and expressions of c-myc and c-fos compared with the control group(P < 0.05). However, Pretreatment with anti-CGRP antibody and CGRP(837) could significantly weaken the inhibitory effect of E-EPC-CM on proliferation of VSMCs induced by AngII (P < 0.05). EPCs exert anti-proliferative effects on VSMCs mediated by the release of CGRP.

Authentication of the family Polygonaceae in Chinese pharmacopoeia by DNA barcoding technique

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants belonging to the family Polygonaceae in Chinese pharmacopoeia possess important medicinal efficacy in traditional Chinese medicines.

AIM OF THE STUDY

DNA barcodes are first used to discriminate the Polygonaceae in Chinese pharmacopoeia and their adulterants.

MATERIALS AND METHODS

DNA samples, extracted from thirty-eight specimens belonging to eighteen species in Polygonaceae, were used as templates. Eight candidate barcodes were amplified by polymerase chain reaction. Sequence analysis was accomplished by CodonCode Aligner V 2.06 and DNAman V 6. Species identification was performed using MEGA V 4.0.

RESULTS

The amplification efficiency of six candidate DNA barcodes (rbcL, trnH-psbA, ndhJ, rpoB, rpoC1, accD) was 100%, while the efficiency of YCF5 and nrITS was 56% and 44%, respectively. The interspecific divergence was highest for the trnH-psbA (20.05%), followed by the nrITS (14.01%) across all species pairs, while intraspecific variation both within populations and between populations was absent (0.0%). The trnH-psbA can not only distinguish ten species of Polygonaceae in Chinese pharmacopoeia, but also recognize eight other species of Polygonaceae including their adulterants.

CONCLUSION

Our findings show that DNA barcoding is an efficient tool for identification of Polygonaceae in Chinese pharmacopoeia and their adulterants.