Endothelium-dependent relaxation of rat aorta by butein, a novel cyclic AMP-specific phosphodiesterase inhibitor

Vasorelaxant effects of biochemical constituents of various medicinal plants and their benefits in diabetes

Endothelial function plays a pivotal role in cardiovascular health, and dysfunction in this context diminishes vasorelaxation concomitant with endothelial activity. The nitric oxide-cyclic guanosine monophosphate pathway, prostacyclin-cyclic adenosine monophosphate pathway, inhibition of phosphodiesterase, and the opening of potassium channels, coupled with the reduction of calcium levels in the cell, constitute critical mechanisms governing vasorelaxation. Cardiovascular disease stands as a significant contributor to morbidity and mortality among individuals with diabetes, with adults afflicted by diabetes exhibiting a heightened cardiovascular risk compared to their non-diabetic counterparts. A plethora of medicinal plants, characterized by potent pharmacological effects and minimal side effects, holds promise in addressing these concerns. In this review, we delineate various medicinal plants and their respective biochemical constituents, showcasing concurrent vasorelaxant and anti-diabetic activities.

Network pharmacology and molecular docking reveal the effective substances and active mechanisms of Dalbergia Odoriferain protecting against ischemic stroke

Dalbergia Odorifera (DO) has been widely used for the treatment of cardiovascular and cerebrovascular diseasesinclinical. However, the effective substances and possible mechanisms of DO are still unclear. In this study, network pharmacology and molecular docking were used toelucidate the effective substances and active mechanisms of DO in treating ischemic stroke (IS). 544 DO-related targets from 29 bioactive components and 344 IS-related targets were collected, among them, 71 overlapping common targets were got. Enrichment analysis showed that 12 components were the possible bioactive components in DO, which regulating 9 important signaling pathways in 3 biological processes including 'oxidative stress' (KEGG:04151, KEGG:04068, KEGG:04915), 'inflammatory response'(KEGG:04668, KEGG:04064) and 'vascular endothelial function regulation'(KEGG:04066, KEGG:04370). Among these, 5 bioactive components with degree≥20 among the 12 potential bioactive components were selected to be docked with the top5 core targets using AutodockVina software. According to the results of molecular docking, the binding sites of core target protein AKT1 and MOL002974, MOL002975, and MOL002914 were 9, 8, and 6, respectively, and they contained 2, 1, and 0 threonine residues, respectively. And some binding sites were consistent, which may be the reason for the similarities and differences between the docking results of the 3 core bioactive components. The results of in vitro experiments showed that OGD/R could inhibit cell survival and AKT phosphorylation which were reversed by the 3 core bioactive components. Among them, MOL002974 (butein) had a slightly better effect. Therefore, the protective effect of MOL002974 (butein) against cerebral ischemia was further evaluated in a rat model of middle cerebral artery occlusion (MCAO) by detecting neurological score, cerebral infarction volume and lactate dehydrogenase (LDH) level. The results indicated that MOL002974 (butein) could significantly improve the neurological score of rats, decrease cerebral infarction volume, and inhibit the level of LDH in the cerebral tissue and serum in a dose-dependent manner. In conclusion, network pharmacology and molecular docking predicate the possible effective substances and mechanisms of DO in treating IS. And the results are verified by the in vitro and in vivo experiments. This research reveals the possible effective substances from DO and its active mechanisms for treating IS and provides a new direction for the secondary development of DO for treating IS.

Natural Molecules as Talented Inhibitors of Nucleotide Pyrophosphatases/Phosphodiesterases (PDEs)

BACKGROUND

Phosphodiesterases (PDEs) are a wide group of enzymes with multiple therapeutic actions, including vasorelaxation, cardiotonic, antidepressant, anti-inflammatory, antithrombotic, anti-spasmolytic, memory-enhancing, and anti-asthmatic. PDEs with eleven subtypes from PDE-1 to PDE-11 typically catalyze the cleavage of the phosphodiester bond and, hence, degrades either cyclic adenosine monophosphate (cAMP) or cyclic guanosine monophosphate (cGMP).

OBJECTIVE

Several selective or non-selective inhibitors of the PDE subtypes are used clinically, i.e. sildenafil, rolipram, cysteine, etc. Recently, interest in plant-based pharmacologically bioactive compounds having potent PDEs inhibitory potential has increased. Purposely, extensive research has been carried out on natural products to explore new inhibitors of various PDEs. Therefore, this review summarizes the published data on natural PDEs inhibitors and their potential therapeutic applications.

METHODS

For this purpose, natural compounds with PDE inhibitory potential have been surveyed through several databases, including PubMed, Web of Sciences (WoS), Scopus, and Google Scholar.

RESULTS

According to a detailed literature survey, the most promising class of herbal compounds with PDE-inhibiting property has been found to belong to phenolics, including flavonoids (luteolin, kaempferol, icariin, etc.). Many other encouraging inhibitors from plants have also been identified, such as coumarins (23, 24) (licoarylcoumarin and glycocoumarin,), saponins ( agapanthussaponins), lignans (31, 33) [(±)-schizandrin and kobusin], terpenes (28, 29, 31) (perianradulcin A, quinovic acid, and ursolic acid), anthraquinones (18, 19) (emodin and chrysophanol), and alkaloids (Sanjoinine-D) (36).

CONCLUSION

In this review, studies have revealed the PDE-inhibitory potential of natural plant extracts and their bioactive constituents in treating various diseases; however, further clinical studies comprising synergistic use of different therapies (synthetic & natural) to acquire multi-targeted results might also be a promising option.

Discovery of pyridoindole derivatives as potential inhibitors for phosphodiesterase 5A: in silico and in vivo studies

The aim of this work was to synthesise derivatives from identified plant based pyridoindole lead scaffold, and to assess phosphodiesterase 5A inhibitory potential by in silico and in vivo. Pyridoindole derivatives were synthesised by using six-stage reactor. In silico screening was carried out by grip-based docking methodology. In step-I, tryptophan as a starting material was reacted with different aldehydes and ketones to obtain 11 molecules. In step-II, obtained molecules were reacted with ethanol and benzyl alcohols to obtain D1 to D22 derivatives. In silico investigation resulted in best three molecules D12, D4 and D8 with promising BE score. Oral acute toxicity study of selected molecules resulted in LD50 value 500 mg/kg in rats. The result of in vivo antihypertensive study shown that molecule D12 was found to be the best antihypertensive lead molecule. This study could be a best platform to tailor novel biomolecules for inhibiting phosphodiesterase 5A enzyme in hypertension management.

Secondary Metabolites of Plants as Modulators of Endothelium Functions

According to the World Health Organization, cardiovascular diseases are the main cause of death worldwide. They may be caused by various factors or combinations of factors. Frequently, endothelial dysfunction is involved in either development of the disorder or results from it. On the other hand, the endothelium may be disordered for other reasons, e.g., due to infection, such as COVID-19. The understanding of the role and significance of the endothelium in the body has changed significantly over time—from a simple physical barrier to a complex system encompassing local and systemic regulation of numerous processes in the body. Endothelium disorders may arise from impairment of one or more signaling pathways affecting dilator or constrictor activity, including nitric oxide–cyclic guanosine monophosphate activation, prostacyclin–cyclic adenosine monophosphate activation, phosphodiesterase inhibition, and potassium channel activation or intracellular calcium level inhibition. In this review, plants are summarized as sources of biologically active substances affecting the endothelium. This paper compares individual substances and mechanisms that are known to affect the endothelium, and which subsequently may cause the development of cardiovascular disorders.

New flavonoid-based compound synthesis strategy for antihypertensive drug development

Hypertension is one of the leading causes of mortality in relation to the cardiovascular conditions and easily the most overlooked and poorly managed disease in mankind. With well over 200 drugs available in the market globally, there is still an urgency to search for antihypertensive alternatives due to the subpar efficacy and unwarranted side effects of the current choices. Present studies reported over 250 types of plant-derived compounds were being investigated for potential pharmacological effects on the vasculature in the last 3 decades. There were numerous literatures that claimed various compounds exhibiting vasorelaxant properties to a certain extent with low numbers of these compounds being successfully adapted into the current medicinal practice for treatment of hypertension. The issue is the scarcity of reviews that summarizes the discovery of this field and the lack of thorough comparison of these compounds to identify which of these vasodilators should be the next face of hypertension management. Thus, this review is aiming towards identifying the relationship between a major class of plant-derived compounds, flavonoid's activity as a vasodilator with their signalling pathways and their structural characteristics according to their vasorelaxant properties. Interestingly, we found that both nitric oxide and voltage-operated calcium channels pathways, and two of the flavonoid's structural characteristics play crucial roles in eliciting strong vasorelaxant effects. We have faith that the insights of this review will serve as a reference for those researching similar topics in the future and potentially lead to the development of more promising antihypertensive alternative.

Dalbergia odorifera: A review of its traditional uses, phytochemistry, pharmacology, and quality control

ETHNOPHARMACOLOGICAL RELEVANCE

Dalbergia odorifera, a traditional herbal medicine, has long been used in China for dissipating blood stasis, regulating the flow of qi, and relieving pain.

AIM OF THIS REVIEW

This review aims to provide comprehensive and up-to-date information about the traditional uses, phytochemistry, pharmacology, and quality control of D. odorifera. Additionally, perspectives for possible future investigations on D. odorifera are also discussed.

MATERIALS AND METHODS

Information on D. odorifera was obtained from a library database and electronic searches (e.g., Elsevier, Springer, ScienceDirect, Wiley, Web of Science, PubMed, Google Scholar, China Knowledge Resource Integrated).

RESULTS

According to classical Chinese herbal texts and the Chinese Pharmacopoeia, D. odorifera promotes blood circulation, relieves pain, and eliminates blood stasis, and it can be used to treat cardio-cerebrovascular diseases in traditional Chinese medicine prescriptions. The chemical constituents of D. odorifera have been well studied, with approximately 175 metabolites having been identified, including flavonoids, phenols, arylbenzofurans, and quinones. The species also contains well-studied volatile oil. Its flavonoids and volatile oil are generally considered to be essential for its pharmacological activity. Modern pharmacology research has confirmed that isolated components and crude extracts of D. odorifera possess wide-ranging pharmacological effects, including anti-inflammatory, anti-angina, anti-oxidative, and other activities. Additionally, there are few quality control studies on D. odorifera.

CONCLUSIONS

To date, significant progress has been made in D. odorifera phytochemistry and pharmacology. Thus, modern pharmacological research has provided some evidence for local or traditional uses. D. odorifera also showed therapeutic potential in cardiovascular and coronary heart diseases. However, the present findings are insufficient to explain its mechanisms of action. Additionally, the mechanism of heartwood formation, artificial induction technology for heartwood production, and quality control of D. odorifera require further detailed research.

Hetero-Tricyclic Lead Scaffold as Novel PDE5A Inhibitor for Antihypertensive Activity: In Silico Docking Studies

Objective:

To screen the phytochemicals for phosphodiesterase 5A (PDE5A) inhibitory potential and identify lead scaffolds of antihypertensive phytochemicals using in silico docking studies.

Methods:

In this perspective, reported 269 antihypertensive phytochemicals were selected. Sildenafil, a PDE5A inhibitor was used as the standard. In silico docking study was carried out to screen and identify the inhibiting potential of the selected phytochemicals against PDE5A enzyme using vLife MDS 4.4 software.

Results:

Based on docking score, π-stacking, H-bond and ionic interactions, 237 out of 269 molecules were selected which have shown one or more interactions. Protein residue Gln817A was involved in H-boding whereas Val782A, Phe820A and Leu804A were involved in π-stacking interaction with ligand. The selected 237 phytochemicals were structurally diverse, therefore 82 out of 237 molecules with one or more tricycles were filtered out for further analysis. Amongst tricyclic molecules, 14 molecules containing nitrogen heteroatom were selected for lead scaffold identification which finally resulted in three different basic chemical backbones like pyridoindole, tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline as lead scaffolds.

Conclusion:

In silico docking studies revealed that nitrogen-containing tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline tricyclic lead scaffolds have emerged as novel PDE5A inhibitors for antihypertensive activity. The identified lead scaffolds may provide antihypertensive lead molecules after its optimization.

Discovery of two novel hetero-tricyclic lead scaffolds as PDE5A inhibitor: virtual screening, molecular docking and pharmacophore modeling approach

Phosphodiesterase 5A enzyme has been the upcoming and promising target in hypertension management. In this research, reported 270 bioactive natural products having antihypertensive potential were selected and docked against PDE5A using vLife MDS 4.6 software. Based on docking score, π-stacking, H-bond and ionic interactions with PDE5A, 82 tricyclic compounds were selected for further study. Protein residue Gln817A was associated in H-boding, Leu804A in ionic interaction whereas Val782A and Phe820A were associated in π-stacking interaction with ligand. In silico docking studies resulted in discovery of oxygen containing naphthofuran and nitrogen and oxygen containing pyrano quinolizine tricyclic lead scaffolds as novel PDE5A inhibitors. Additionally, developed pharmacophore model suggested that one centre of hydrogen bond acceptor, one aromatic centre and two aliphatic centres are minimum pharmacophoric features required in the molecule so as to show sildenafil like activity. The identified lead scaffolds would provide novel platform for drug discovery of bioactive natural products.

A Review on the Medicinal Plant Dalbergia odorifera Species: Phytochemistry and Biological Activity

The crucial medicinal plant Dalbergia odorifera T. Chen species belongs to genus Dalbergia, with interesting secondary metabolites, consisting of main classes of flavonoid, phenol, and sesquiterpene derivatives, as well as several arylbenzofurans, quinones, and fatty acids. Biological studies were carried out on extracts, fractions, and compounds from this species involved in cytotoxic assays; antibacterial, antioxidative, anti-inflammatory, antithrombotic, antiplatelet, antiosteosarcoma, antiosteoporosis, antiangiogenesis, and prostaglandin biosynthetic enzyme inhibition activities; vasorelaxant activities; alpha-glucosidase inhibitory activities; and many other effects. In terms of the valuable resources for natural new drugs development, D. odorifera species are widely used as medicinal drugs in many countries for treatment of cardiovascular diseases, cancer, diabetes, blood disorders, ischemia, swelling, necrosis, or rheumatic pain. Although natural products from this plant have been increasingly playing an important role in drug discovery programs, there is no supportive evidence to provide a general insight into phytochemical studies on D. odorifera species and biological activities of extracts, fractions, and isolated compounds. To a certain extent, this review deals with an overview of almost naturally occurring compounds from this species, along with extensive coverage of their biological evaluations.

Metabonomic Strategy for the Evaluation of Chinese Medicine Salvia miltiorrhiza and Dalbergia odorifera Interfering with Myocardial Ischemia/Reperfusion Injury in Rats

Extract of Salvia miltiorrhiza and Dalbergia Odorifera (SM-DOO) has been traditionally used for the prevention and treatment of cardiovascular diseases. However, information regarding the pharmacodyamic material basis and potential mechanism remain unknown. Male Sprague-Dawley rats were divided into four groups: Sham, Model, Diltiazem, and SM-DOO group, n = 6. Rats were pretreated with homologous drugs for 7 days, and then subjected to 30 minutes of ischemia followed by 180 minutes of reperfusion. Cardioprotection effects of SM-DOO on myocardial ischemia/reperfusion (MI/R) injury rats were examined by hemodynamics, infarct area, histopathology, biochemical indicators, and Western blot analysis. Metabonomics technology was further performed to evaluate the endogenous metabolites profiling systematically. According to the results of pattern recognition analysis, a clear separation of MI/R injury in the Model group and Sham group was achieved and SM-DOO pretreatment group was located much closer to the Sham group than the Model group, which was consistent with results of biochemistry and histopathological assay. Moreover, potential biomarkers were identified to elucidate the drug mechanism of SM-DOO, which may be related with pathways of energy metabolism, especially tricarboxylic acid (TCA) cycle (citric acid) and β-oxidation of fatty acids (3-hydroxybutyric, palmitoleic acid, heptadecanoic acid, and arachidonic acid). In addition, the protein expressions of p-AMPK and p-ACC in the SM-DOO group were significantly elevated, while the levels of carnitine palmitoyl-CoA transferase-1 (CPT-1), p-PDK, and p-PDC were dramatically reduced by SM-DOO. In conclusion, SM-DOO pretreatment could ameliorate MI/R injury by intervening with energy metabolism, especially TCA cycle and β-oxidation of fatty acids. This work showed that the metabonomics method combinate with conventional pharmacological methods is a promising tool in the efficacy and mechanism research of traditional Chinese medicines.

Butein provides neuroprotective and anti-neuroinflammatory effects through Nrf2/ARE-dependent haem oxygenase 1 expression by activating the PI3K/Akt pathway

BACKGROUND AND PURPOSE

Butein, 3,4,2',4'-tetrahydroxychalcone, has various pharmacological effects. However, no study has demonstrated the specific neurobiological mechanisms of the effects of butein in neuronal cells. The present study examined the role of butein as an antioxidative and anti-inflammatory inducer of haem oxygenase 1 (HO1) in mouse hippocampal HT22, BV2 microglial and primary mouse hippocampus neurons.

EXPERIMENTAL APPROACH

We investigated the neuroprotective effects of butein on glutamate-induced HT22 cell and primary mouse hippocampal neuron death and its anti-neuroinflammatory effects on LPS-induced activation of BV2 cells. We elucidated the underlying mechanisms by assessing the involvement of NF-κB, HO1, nuclear factor-E2-related factor 2 (Nrf2) and Akt signalling.

KEY RESULTS

Butein decreased cellular oxidative injury and the production of ROS in glutamate-treated HT22 cells and primary mouse hippocampal neurons. Furthermore, butein suppressed LPS-induced pro-inflammatory enzymes and mediators in BV2 microglia. Butein inhibited IL-6, IL-1β and TNF-α production and mRNA expression. In addition, butein decreased NO and PGE2 production and inducible NOS and COX-2 expression through the NF-κB signalling pathway. Butein up-regulated Nrf2/ARE-mediated HO1 expression through the PI3K/Akt pathway and this was positively associated with its cytoprotective effects and anti-neuroinflammatory actions.

CONCLUSION AND IMPLICATIONS

Our results indicate that butein effectively prevents glutamate-induced oxidative damage and LPS-induced activation and that the induction of HO1 by butein through the PI3K/Akt pathway and Nrf2 activation appears to play a pivotal role in its effects on neuronal cells. Our results provide evidence for the neuroprotective properties of butein.

Butein and Its Role in Chronic Diseases

Natural compounds isolated from various plant sources have been used for therapeutic purpose for centuries. These compounds have been routinely used for the management of various chronic ailments and have gained considerable attention because of their significant efficacy and comparatively low side effects. Butein, a chacolnoid compound that has been isolated from various medicinal plants has exhibited a wide range of beneficial pharmacological effects, such as anti-inflammatory, anticancer, antioxidant, and anti-angiogenic in diverse disease models. This article briefly summarizes the past published literature related to the therapeutic and protective effects of butein, as demonstrated in various models of human chronic diseases. Further analysis of its important cellular targets, toxicity, and pharmacokinetic profile may further significantly expand its therapeutic application.

Butein suppresses breast cancer growth by reducing a production of intracellular reactive oxygen species

Background

Butein has various functions in human diseases including cancer. While anti-cancer effects of butein have been revealed, it is urgent to understand a unique role of butein against cancer. In this study, we demonstrate that butein inhibition of reactive oxygen species (ROS) production results in suppression of breast cancer growth.

Methods

Different breast cancer cell lines were treated with butein and then subjected to cell viability and apoptosis assays. Butein-sensitive or -resistant breast cancer cells were injected into mammary fat pads of immunocompromised mice and then butein was injected. Breast cancer cells were categorized on the basis of butein sensitivity.

Results

Butein reduced viabilities of different breast cancer cells, while not affecting those of HER2-positive (HER2⁺) HCC-1419, SKBR-3 and HCC-2218 breast cancer cells. Butein reduction of ROS levels was correlated with apoptotic cell death. Furthermore, butein reduction of ROS level led to inhibitions of AKT phosphorylation. N-acetyl-L-cysteine (NAC), a free radical scavenger, also reduced ROS production and AKT phosphorylation, resulting in apoptotic cell death. In contrast, inhibitory effects of both butein and NAC on ROS production and AKT phosphorylation were not detected in butein-resistant HER2⁺ HCC-1419, SKBR-3 and HCC-2218 cells. In the in vivo tumor growth assays, butein inhibited tumor growth of butein-sensitive HER2⁺ BT-474 cells, while not affecting that of butein-resistant HER2⁺ HCC-1419 cells. Moreover, butein inhibition of ROS production and AKT phosphorylation was confirmed by in vivo tumor growth assays.

Conclusions

Our study first reveals that butein causes breast cancer cell death by the reduction of ROS production. Therefore, our finding provides better knowledge for butein effect on breast cancer and also suggests its treatment option.

The neoflavonoid latifolin isolated from MeOH extract of Dalbergia odorifera attenuates inflammatory responses by inhibiting NF-κB activation via Nrf2-mediated heme oxygenase-1 expression

In Korea and China, the heartwood of Dalbergia odorifera T. Chen is an important traditional medicine used to treat blood disorders, ischemia, swelling, and epigastric pain. In this study, we investigated the inhibitory effects of latifolin, a major neoflavonoid component isolated from the MeOH extract of D. odorifera, on the inflammatory reaction of thioglycollate-elicited peritoneal macrophages exposed to lipopolysaccharide, with a particular focus on heme oxygenase-1 (HO-1) expression and nuclear factor-κB (NF-κB) signaling. Latifolin significantly inhibited the protein and mRNA expression of inducible nitric oxide synthase and COX-2, reduced NO, prostaglandins E2, tumor necrosis factor-α, and interleukin-1β production in primary murine peritoneal macrophages exposed to lipopolysaccharide. Latifolin also suppressed inhibitor κB-α levels, NF-κB nuclear translocation, and NF-κB DNA-binding activity. Furthermore, latifolin upregulated HO-1 expression via nuclear transcription factor-E2-related factor 2 (Nrf2) nuclear translocation. In addition, using inhibitor tin protoporphyrin IX (SnPP), an inhibitor of HO-1, it was verified that the inhibitory effects of latifolin on the proinflammatory mediators and NF-κB DNA-binding activity were associated with the HO-1 expression. These results suggested that the latifolin-mediated up-regulation of HO-1 expression played a critical role in anti-inflammatory effects in macrophages. This study therefore identified potent therapeutic effects of latifolin, which warrants further investigation as a potential treatment for inflammatory diseases.

Butein Inhibits Angiogenesis of Human Endothelial Progenitor Cells via the Translation Dependent Signaling Pathway

Compelling evidence indicates that bone marrow-derived endothelial progenitor cells (EPCs) can contribute to postnatal neovascularization and tumor angiogenesis. EPCs have been shown to play a "catalytic" role in metastatic progression by mediating the angiogenic switch. Understanding the pharmacological functions and molecular targets of natural products is critical for drug development. Butein, a natural chalcone derivative, has been reported to exert potent anticancer activity. However, the antiangiogenic activity of butein has not been addressed. In this study, we found that butein inhibited serum- and vascular endothelial growth factor- (VEGF-) induced cell proliferation, migration, and tube formation of human EPCs in a concentration dependent manner without cytotoxic effect. Furthermore, butein markedly abrogated VEGF-induced vessels sprouting from aortic rings and suppressed microvessel formation in the Matrigel implant assay in vivo. In addition, butein concentration-dependently repressed the phosphorylation of Akt, mTOR, and the major downstream effectors, p70S6K, 4E-BP1, and eIF4E in EPCs. Taken together, our results demonstrate for the first time that butein exhibits the antiangiogenic effect both in vitro and in vivo by targeting the translational machinery. Butein is a promising angiogenesis inhibitor with the potential for treatment of cancer and other angiogenesis-related diseases.

Vasodilator compounds derived from plants and their mechanisms of action

The present paper reviews vasodilator compounds isolated from plants that were reported in the past 22 years (1990 to 2012) and the different mechanisms of action involved in their vasodilator effects. The search for reports was conducted in a comprehensive manner, intending to encompass those metabolites with a vasodilator effect whose mechanism of action involved both vascular endothelium and arterial smooth muscle. The results obtained from our bibliographic search showed that over half of the isolated compounds have a mechanism of action involving the endothelium. Most of these bioactive metabolites cause vasodilation either by activating the nitric oxide/cGMP pathway or by blocking voltage-dependent calcium channels. Moreover, it was found that many compounds induced vasodilation by more than one mechanism. This review confirms that secondary metabolites, which include a significant group of compounds with extensive chemical diversity, are a valuable source of new pharmaceuticals useful for the treatment and prevention of cardiovascular diseases.

Butein protects human dental pulp cells from hydrogen peroxide-induced oxidative toxicity via Nrf2 pathway-dependent heme oxygenase-1 expressions

Rhus verniciflua Stokes is a plant that is native to East Asian countries, such as Korea, China, and Japan. Butein, a plant polyphenol, is one of the major active components of R. verniciflua. Reactive oxygen species (ROS), produced via dental adhesive bleaching agents and pulpal disease, can cause oxidative stress. Here, we found that butein possesses cytoprotective effects on hydrogen peroxide (H2O2)-induced dental cell death. H2O2 is a representative ROS and causes cell death through necrosis in human dental pulp (HDP) cells. H2O2-induced cytotoxicity and production of ROS were blocked in the presence of butein, and these effects were dose dependent. Butein also increased heme oxygenase-1 (HO-1) protein expression and HO activity. In addition, butein-dependent HO-1 expression was required for the inhibition of H2O2-induced cell death and ROS generation. Furthermore, butein treatment caused nuclear accumulation of nuclear factor-E2-related factor 2 (Nrf2) and increased the promoter activity of antioxidant response elements (AREs). Treatment of HDP cells with a c-Jun NH2-terminal kinase (JNK) inhibitor also reduced butein-induced HO-1 expression, and butein treatment led to increased JNK phosphorylation. These results indicate that butein may be used to prevent functional dental cell death and thus may be useful as a pulpal disease agent.

Butein from Rhus verniciflua protects pancreatic β cells against cytokine-induced toxicity mediated by inhibition of nitric oxide formation

Butein (3,4,2',4'-tetrahydroxychalcone), a plant polyphenol, is a major component in isolate of Rhus verniciflua STOKES (Anacardiaceae). It is shown to exert various potent effects such as antioxidant, antiinflammatory induction of apoptosis among many properties. In this study, we investigated the effect of butein on cytokine-induced β-cell damage. Pre-treatment with butein is shown to increase the viability of cytokine-treated INS-1 cells at concentrations of 15-30 µM. Butein prevented cytokine-mediated cell death, as well as nitric oxide (NO) production, and these effects correlated well with reduced levels of protein expression of the inducible nitric oxide synthase (iNOS). Furthermore, the molecular mechanisms by which butein inhibits iNOS gene expression appeared to be through the inhibition of nuclear factor-κB (NF-κB) translocation. In a second set of experiments, rat islets were used to demonstrate the protective effects of butein and the results were essentially the same as those observed in Beutin pretreated INS-1 cells. Butein prevented cytokine-induced NO production, iNOS expression, and NF-κB translocation and inhibition of glucose-stimulated insulin secretion (GSIS). In conclusion, these results suggest that butein can be used for the prevention of functional β-cell damage and preventing the progression of Type 1 diabetes mellitus (T1DM).

The biochemical and cellular basis for nutraceutical strategies to attenuate neurodegeneration in Parkinson's disease

Future therapeutic intervention that could effectively decelerate the rate of degeneration within the substantia nigra pars compacta (SNc) could add years of mobility and reduce morbidity associated with Parkinson’s disease (PD). Neurodegenerative decline associated with PD is distinguished by extensive damage to SNc dopaminergic (DAergic) neurons and decay of the striatal tract. While genetic mutations or environmental toxins can precipitate pathology, progressive degenerative succession involves a gradual decline in DA neurotransmission/synaptic uptake, impaired oxidative glucose consumption, a rise in striatal lactate and chronic inflammation. Nutraceuticals play a fundamental role in energy metabolism and signaling transduction pathways that control neurotransmission and inflammation. However, the use of nutritional supplements to slow the progression of PD has met with considerable challenge and has thus far proven unsuccessful. This review re-examines precipitating factors and insults involved in PD and how nutraceuticals can affect each of these biological targets. Discussed are disease dynamics (Sections 1 and 2) and natural substances, vitamins and minerals that could impact disease processes (Section 3). Topics include nutritional influences on α-synuclein aggregation, ubiquitin proteasome function, mTOR signaling/lysosomal-autophagy, energy failure, faulty catecholamine trafficking, DA oxidation, synthesis of toxic DA-quinones, o-semiquinones, benzothiazolines, hyperhomocyseinemia, methylation, inflammation and irreversible oxidation of neuromelanin. In summary, it is clear that future research will be required to consider the multi-faceted nature of this disease and re-examine how and why the use of nutritional multi-vitamin-mineral and plant-based combinations could be used to slow the progression of PD, if possible.

Antimicrobial and antioxidative activities of bioactive constituents from Hydnophytum formicarum Jack

Hydnophytum formicarum Jack. (Rubiaceae) is a medicinal plant whose tubers possesses cardiovascular, anti-inflammatory and antiparasitic effects and have been used for the treatment of hepatitis, rheumatism and diarrhea. Herein we report the isolation of its active constituents and the testing of their antimicrobial activity against 27 strains of microorganisms using an agar dilution method and of their antioxidative activity using the DPPH and SOD assays. The results show that the crude hexane, dichloromethane, ethyl acetate and methanol extracts exert such activities. Particularly, the crude ethyl acetate extract exhibits antigrowth activity against many Gram-positive and Gram-negative bacteria with MIC 256 μg/mL. Shewanella putrefaciens ATCC 8671 is completely inhibited at a lower MIC (128 μg/mL). Interestingly, Corynebacterium diphtheriae NCTC 10356 is inhibited by all the tested extracts. Significantly, the ethyl acetate extract is also the most potent antioxidant, showing 83.31% radical scavenging activity with IC₅₀ 8.40 μg/mL in the DPPH assay. The other extracts display weak to moderate antioxidative activities, ranging from 28.60-56.80% radical scavenging. The SOD assay shows that methanol extract exhibits the highest activity (74.19% inhibition of superoxide radical). The dichloromethane and ethyl acetate extracts display comparable SOD activity. The promising bioactivities of the crude ethyl acetate extract guided the first isolation of bioactive flavonoid and phenolic compounds: isoliquiritigenin (2), protocatechualdehyde (3), butin (4) and butein (5) from this species. Their structures have been fully established by 1D and 2D NMR. In addition, stigmasterol was isolated from the crude hexane and dichloromethane extracts. The antimicrobial and cytotoxic activities of compounds 3-5 were evaluated. The tested compounds were inactive against HuCCA-1 and KB cell lines, showing ED₅₀> 10 μg/mL. Protocatechualdehyde (3) completely inhibits the growth of Plesiomonas shigelloides with MIC ≤60 μg/mL. As a result, we propose that Hydnophytum formicarum Jack. can serve as a new source enriched with potent antioxidative and antimicrobial agents.

Butein, a tetrahydroxychalcone, inhibits nuclear factor (NF)-kappaB and NF-kappaB-regulated gene expression through direct inhibition of IkappaBalpha kinase beta on cysteine 179 residue

Although butein (3,4,2',4'-tetrahydroxychalcone) is known to exhibit anti-inflammatory, anti-cancer, and anti-fibrogenic activities, very little is known about its mechanism of action. Because numerous effects modulated by butein can be linked to interference with the NF-kappaB pathway, we investigated in detail the effect of this chalcone on NF-kappaB activity. As examined by DNA binding, we found that butein suppressed tumor necrosis factor (TNF)-induced NF-kappaB activation in a dose- and time-dependent manner; suppressed the NF-kappaB activation induced by various inflammatory agents and carcinogens; and inhibited the NF-kappaB reporter activity induced by TNFR1, TRADD, TRAF2, NIK, TAK1/TAB1, and IKK-beta. We also found that butein blocked the phosphorylation and degradation of IkappaBalpha by inhibiting IkappaBalpha kinase (IKK) activation. We found the inactivation of IKK by butein was direct and involved cysteine residue 179. This correlated with the suppression of phosphorylation and the nuclear translocation of p65. In this study, butein also inhibited the expression of the NF-kappaB-regulated gene products involved in anti-apoptosis (IAP2, Bcl-2, and Bcl-xL), proliferation (cyclin D1 and c-Myc), and invasion (COX-2 and MMP-9). Suppression of these gene products correlated with enhancement of the apoptosis induced by TNF and chemotherapeutic agents; and inhibition of cytokine-induced cellular invasion. Overall, our results indicated that antitumor and anti-inflammatory activities previously assigned to butein may be mediated in part through the direct inhibition of IKK, leading to the suppression of the NF-kappaB activation pathway.

Preclinical and clinical examinations of Salvia miltiorrhiza and its tanshinones in ischemic conditions

Salvia miltiorrhiza (Labiatae, Laminaceae), danshen, is an annual sage mainly found in China and neighboring countries. The crude drug (dried root) and its preparations are currently used in China to treat patients suffering from heart attack, angina pectoris, stroke and some other conditions. The use of S. miltiorrhiza has been increasing in the management of stroke. Pharmacological examinations showed that the plant and its active ingredients, tanshinones and salvianolic acids, have anticoagulant, vasodilatory, increased blood flow, anti-inflammatory, free radical scavenging, mitochondrial protective and other activities. This review discusses the pharmacology, medicinal chemistry and clinical studies published, especially in China, for danshen and tanshinone preparations. Clinical examinations are evaluated in terms of S. miltiorrhiza preparation, dose, double blinding, control, clinical assessments of outcomes and other parameters. Meta-analyses of S. miltiorrhiza are also discussed.

Flavonoids attenuate cardiovascular disease, inhibit phosphodiesterase, and modulate lipid homeostasis in adipose tissue and liver

Plant flavonoids are widely distributed polyphenolic compounds of the human diet. They consist of six major classes based on specific structural differences: flavonols, flavones, flavanones, catechins, anthocyanidins, and isoflavones. All of the major classes of flavonoids are comprised of three six-membered rings: an aromatic A-ring fused to a heterocyclic C-ring that is attached through a single carbon-carbon bond to an aromatic Bring. Population studies have shown that flavonoid intake is inversely correlated with mortality from cardiovascular disease, and numerous flavonoids of dietary significance have been shown to beneficially impact parameters associated with atherosclerosis, including lipoprotein oxidation, blood platelet aggregation, and vascular reactivity. Therapeutic effects of flavonoids on platelet aggregability and blood pressure have been attributed to competitive inhibition of cyclic nucleotide phosphodiesterase (PDE), an elevation in cAMP level, and subsequent activation of protein kinase A (cAMP-dependent protein kinase). In addition, flavonoids may induce neutral lipid hydrolysis from lipid stores through PDE inhibition in adipose tissue and liver. Indeed, the three-dimensional structure of many flavonoids is sterically and electrostatically compatible with the catalytic site of cAMP PDE3 and PDE4. Flavonoids have also been reported to suppress pathways of lipid biosynthesis and of very low-density lipoprotein production in cultured hepatocytes. Continued studies of the biochemical mechanisms underlying the biological effects of plant flavonoids may uncover new strategies for the treatment of cardiovascular disease, as well as associated conditions such as obesity, hepatic steatosis, and Type 2 diabetes.

The role of phosphodiesterase isoforms 2, 5, and 9 in the regulation of NO-dependent and NO-independent cGMP production in the rat cervical spinal cord

NO-responsive, cGMP-producing structures are abundantly present in the cervical spinal cord. NO-mediated cGMP synthesis has been implicated in nociceptive signaling and it has been demonstrated that cGMP has a role establishing synaptic connections in the spinal cord during development. As cGMP levels are controlled by the activity of soluble guanylyl cyclase (synthesis) and the phosphodiesterase (PDE) activity (breakdown), we studied the influence of PDE activity on NO-stimulated cGMP levels in the rat cervical spinal cord. cGMP-immunoreactivity (cGMP-IR) was localized in sections prepared from slices incubated in vitro. A number of reported PDE isoform-selective PDE inhibitors was studied in combination with diethylamineNONOate (DEANO) as a NO-donor including isobutyl-methylxanthine (IBMX) as a non-selective PDE inhibitor. We studied 8-methoxy-IBMX as a selective PDE1 inhibitor, erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and BAY 60-7550 as selective PDE2 inhibitors, sildenafil as a selective PDE5 inhibitor, dipyridamole as a mixed type PDE5 and PDE10 inhibitor, rolipram as a PDE4 inhibitor, and SCH 81566 as a selective PDE9 inhibitor. cGMP-IR structures (nerve fibers, axons, and terminals) were characterized using the following neurochemical markers: vesicular transporter molecules for acetylcholine, GABA, and glutamate (type 1 and type 2), parvalbumin, glutamate transporter molecule EAAT3, synaptophysin, substance P, calcitonin gene-related peptide, and isolectin B4. Most intense cGMP-IR was observed in the dorsal lamina. Ventral motor neurons were devoid of cGMP-IR. cGMP-IR was observed in GABAergic, and glutamatergic terminals in all gray matter laminae. cGMP-IR was abundantly colocalized with anti-vesicular glutamate transporter 2 (vGLUT2), however not with the anti-vesicular glutamate transporter 1 (vGLUT1), suggesting a functional difference between structures expressing vGLUT1 or vGLUT2. cGMP-IR did not colocalize with substance P- or calcitonin-gene related peptide-IR structures, however did partially colocalize with isolectin B4 in the dorsal horn. cGMP-IR in cholinergic structures was observed in dorsal root fibers entering the spinal cord, occasionally in laminae 1-3, in laminae 8 and 9 in isolated boutons and in the C-type terminals, and in small cells and varicosities in lamina 10. This latter observation suggests that the proprioceptive interneurons arising in lamina 10 are also NO-responsive. No region-specific nor a constant co-expression of cGMP-IR with various neuronal markers was observed after incubation of the slices with one of the selected PDE inhibitors. Expression of the mRNA of PDE2, 5, and 9 was observed in all lamina. The ventral motor neurons and the ependymal cells lining the central canal expressed all three PDE isoforms. Incubation of the slices in the presence of IBMX, DEANO in combination with BAY 41-2272, a NO-independent activator of soluble guanylyl cyclase, provided evidence for endogenous NO synthesis in the slice preparations and enhanced cGMP-IR in all lamina. Under these conditions cGMP-IR colocalized with substance P in a subpopulation of substance P-IR fibers. It is concluded that NO functions as a retrograde neurotransmitter in the spinal cord but that also postsynaptic structures are NO-responsive by producing cGMP. cGMP-IR in a subpopulation of isolectin B4 positive fibers and boutons is indicative for a role of NO-cGMP signaling in nociceptive processing. cGMP levels in the spinal cord are controlled by the concerted action of a number of PDE isoforms, which can be present in the same cell.

Simultaneous determination of 10 major flavonoids in Dalbergia odorifera by high performance liquid chromatography

A reversed-phase liquid chromatographic method was developed for the simultaneous quantification of 10 major flavonoids, namely butin, (3R)-4'-methoxy-2',3,7-trihydroxyisoflavanone, liquiritigenin, melanettin, violanone, vistitone, formononetin, dalbergin, sativanone and medicarpin in the heartwood of Dalbergia odorifera, an important traditional Chinese medicine. Samples were extracted with 60% methanol. The optimal conditions of separation and detection were achieved on an Agilent Zorbax SB-C18 column (250 mm x 4.6 mm, 5 microm) with a gradient of acetonitrile and 0.3% (v/v) aqueous acetic acid, at a flow rate of 0.8 ml/min, detected at 275 nm. The complete separation was obtained within 55 min for the 10 target compounds. All calibration curves showed good linearity (r2>0.999) within test ranges. The assay was reproducible with overall intra- and inter-day variation of less than 3%. The mean recovery of the method was 100+/-10%, with R.S.D. less than 5%. The current assay method was considered to be suitable for the quality control of D. odorifera samples and could be readily utilized for the determination of the active principles present in this medicinal herb.

The plant polyphenol butein inhibits testosterone-induced proliferation in breast cancer cells expressing aromatase

Chalcones are precursor compounds for flavonoid synthesis in plants, and they can also be synthesized in laboratory. Previous study has documented some of the pharmacological applications of these compounds. Estrogen has long been associated with the initiation and promotion of breast cancer. Inhibiting estrogen synthesis can be effective in the prevention and treatment of the disease. Since most breast cancers received estrogen supplied from local tissues, we employed a breast cancer cell line expressing aromatase to screen for the inhibitory potentials of five hydroxychalcones, i.e. 2-hydroxychalcone, 2'-hydroxychalcone, 4-hydroxychalcone, 4,2',4'-trihydroxy-chalcone (isoquiritigenin), 3,4,2',4'-tetrahydroxychalcone (butein). In the preliminary results, butein was found to be the strongest inhibitor among the tested compounds, and its IC(50) value was 3.75 microM. Subsequent enzyme kinetic study revealed that butein acted on aromatase with a mixed type of inhibition and the K(i) value was determined to be 0.32 microM. Cell proliferation assay indicated that the cell number increased by 10 nM-testosterone treatment was significantly reduced by 5 microM butein, and the administration of flutamide could not reverse the effect. The present study illustrated that butein was an aromatase inhibitor and a potential natural alternative for the chemoprevention or therapy of breast cancer.

Liquid chromatography/electrospray ionization mass spectrometry for the characterization of twenty-three flavonoids in the extract of Dalbergia odorifera

A method incorporating high-performance liquid chromatography (HPLC) with electrospray ionization and tandem mass spectrometry, with parallel analysis by HPLC with UV detection using a diode-array detector, was developed for the qualitative characterization of flavonoids in D. odorifera. Twenty-three flavonoids, including six isoflavones, six neoflavones, four isoflavanones, three flavanones, two chalcones, one isoflavanonol and one pterocarpan, were unambiguously identified by comparing their retention times, UV and MS spectra with those of authentic compounds. Furthermore, the collision-induced dissociations of the [M-H]- ions were studied to clarify the MS behavior of the different types of flavonoids. In negative ion ESI-MS all the flavonoids yielded prominent [M-H]- ions in the first order mass spectra. Fragments involving losses of CH3*, H2O, CO, C2H2O, and CO2 were observed in the MS/MS spectra. Each of the seven types of flavonoid showed characteristic MS/MS fragmentation patterns. The isoflavanones, flavanones and chalcones were observed to undergo retro-Diels-Alder fragmentations. The spectra of almost all the neoflavonoids unexpectedly exhibited only [M-H-CH3]-* radical anions as base peaks without any further fragmentation. Substitution positions also remarkably influenced the fragmentation behavior, which could assist in distinction among the flavonoid isomers. The fragmentation rules deduced here could aid in the characterization of other flavonoids of these types.

Identification and determination of major flavonoids in rat urine by HPLC-UV and HPLC-MS methods following oral administration ofDalbergia odorifera extract

Flavonoids are the main active constituents of Dalbergia odorifera. The excretion of the major flavonoids in rat urine after oral administration of D. odorifera extract was investigated by HPLC-UV and HPLC-MS methods. Utilizing the HPLC-MS technique, 18 flavonoids, including five isoflavones, four isoflavanones, four neoflavones, two flavanones, two chalcones and one isoflavanonol were identified in free form in a urine sample based on the direct comparison of the corresponding tR, UV maximum absorbance (lambda(max)) values and MS data with the authentic standards. The amounts of the prominent flavonoids, (3R)-4'-methoxy-2',3,7-trihydroxyisoflavanone and vestitone, were determined by HPLC-UV with the internal standard method, and the validation procedure confirmed that it afforded reliable analysis of these two analytes in urine after oral administration of D. odorifera extract.

Induction of the anticarcinogenic marker enzyme, quinone reductase, by Dalbergiae Lignum

The effect of an extract of Dalbergiae Lignum and four components that were isolated from the extract on the anticarcinogenic phase II marker enzyme, quinone reductase (QR), was investigated. Of the solvent extracts of Dalbergiae Lignum, the CH2Cl2 fraction was the most potent in inducing QR activity, with a CD value (the concentration required to double the QR activity) of 29.5 microg/mL. The CH2Cl2 extract was further separated into six compounds, four of which were identified as 4-methoxydalbergione, latifolin, 4',6-dihydroxy-7-methoxyflavanone, and obtusafuran. Obtusafuran [CD = 1.1 microM; chemopreventive index (CI) = 101.9] and latifolin (CD = 1.7 microM; CI = 154.6) displayed potent QR inducing activity and high chemopreventive indices. Latifolin and 4-methoxydalbergione were identified as strong DPPH-scavengers with half-maximal free radical scavenging concentrations of 15.9 and 17.2 microM, respectively.

Butein Ameliorates Renal Concentrating Ability in Cisplatin-Induced Acute Renal Failure in Rats

The present study examined whether the cisplatin-induced nephropathy could be ameliorated by administration of butein isolated from the stems of Rhus verniciflua STOCKS. The present study showed that polyuric profile was revealed in cisplatin-induced acute renal failure (ARF) rats associated with decreases in urinary sodium, potassium, chloride, and creatinine excretion, and osmolality. Among these renal functional parameters, urinary volume and osmolality were partially restored by administration of butein (10 mg/kg, i.p.), but electrolytes and creatinine excretion were not restored. Both solute-free water reabsorption and creatinine clearance were also significantly decreased in rats subjected to cisplatin. When butein was administered in rats with cisplatin-induced ARF for 4 d, solute-free water reabsorption was improved by 91% compared with that of cisplatin-induced ARF rats, but creatinine clearance was not restored. The expression levels of aquaporin 2 (AQP 2) in the inner, outer medulla, and cortex were significantly decreased in the kidney of ARF, which were partially reverted by administration of butein. In histological examination of the kidney, butein treatment partially prevented the lesions at tubules of renal cortex in cisplatin-induced ARF rats, while the lesions at glomeruli were not ameliorated. Taken together, butein ameliorates renal concentrating ability via up-regulation of renal AQP 2 water channel in rats with cisplatin-induced ARF without ameliorating effect on renal filtration defect.

Hypotensive effect of butein via the inhibition of angiotensin converting enzyme

Butein (3,4,2',4'-tetrahydroxychalcone), a plant polyphenol, has been known to elucidate endothelium-dependent vasodilation. In the present study, the hypotensive effect of butein and its possible mechanism, especially an angiotensin converting enzyme (ACE) inhibitory effect, were investigated. Intravenous injection of butein lowered the arterial blood pressure of anesthetized rats in a dose-dependent manner. The plasma ACE activities were significantly inhibited by the addition of butein in a dose-dependent manner, the IC(50) value of which was 198 microg/ml (730 microM). Moreover, angiotensin I-induced contraction was markedly attenuated by prior exposure of endothelium-intact aortic rings to butein, but angiotensin II-induced contraction was not altered. These results suggest that butein has a hypotensive effect, at least in part, via the inhibition of angiotensin converting enzyme.

Cardiac effects of salvia miltiorrhiza/dalbergia odorifera mixture, an intravenously applicable Chinese medicine widely used for patients with ischemic heart disease in China

Chronotropic, inotropic and coronary vasodilator actions of the clinically available ampoule preparation of Salvia miltiorrhiza/Dalbergia odorifera mixture were examined using canine isolated, blood-perfused heart preparations. The mixture slightly decreased the sinoatrial rate and significantly increased coronary blood flow, but hardly affected the developed tension of the papillary muscle. The effect on coronary blood flow was induced by at least a 10-fold smaller dose than that which induced the chronotropic effect. These results were quite similar to those of a typical calcium channel blocker, verapamil, used in a previous study, suggesting that the Salvia miltiorrhiza/Dalbergia odorifera mixture may have potential as an anti-anginal drug.

Cancer chemoprevention and apoptosis mechanisms induced by dietary polyphenolics

This review summarises current knowledge on the various molecular chemopreventive or therapeutic mechanisms that may be involved when the administration of flavonoids or polyphenols prevented chemical carcinogenesis in animal models. These mechanisms can be subdivided into the following: 1) the molecular mechanisms involved in preventing carcinogen metabolic activation, 2) the molecular mechanisms for preventing tumour cell proliferation by inactivation or downregulation of prooxidant enzymes or signal transduction enzymes, 3) the molecular cell death mechanisms for the induction of tumour cell death (apoptosis) and the molecular mechanisms for the inhibition of isolated mitochondria functions. Many of the flavonoids and polyphenols found in diets, supplements or herbal medicine were also ranked using "accelerated cytotoxic mechanism screening" by a combinatorial approach utilising isolated rat hepatocytes. A strong correlation of an early collapse of the mitochondrial membrane potential and cell death was found for most of the cytotoxic polyphenols but did not occur with non-toxic polyphenols. This screening could prove useful for eliminating polyphenols that have the potential for adverse health effects and for selecting safe and effective polyphenolic candidates for further development as supplements for preventing cancer or cardiovascular disease. Safety concerns of flavonoid/polyphenol supplements are also reviewed.

2'-hydroxychalcone inhibits nuclear factor-kappaB and blocks tumor necrosis factor-alpha- and lipopolysaccharide-induced adhesion of neutrophils to human umbilical vein endothelial cells

Inhibition of expression of cell adhesion molecules (CAM), including intercellular CAM-1 (ICAM-1), vascular CAM-1 (VCAM-1), and E-selectin, has been shown to be important in controlling various inflammatory diseases. The cell adhesion proteins are induced by various inflammatory cytokines, such as tumor necrosis factor-alpha, interleukin-1, and bacterial lipopolysaccharide. The induction process primarily takes place at the level of transcription, where nuclear factor-kappaB (NF-kappaB) plays a major role. We demonstrate here that 2'-hydroxychalcone inhibits the adhesion of peripheral neutrophils to the endothelial cell monolayers by inhibiting the expression of ICAM-1, VCAM-1, and E-selectin in a concentration-dependent manner. The inhibition by 2'-hydroxychalcone is reversible. 2'-hydroxychalcone inhibits the induction of steady-state transcript levels of ICAM-1, VCAM-1, and E-selectin by tumor necrosis factor-alpha as determined by reverse transcription-polymerase chain reaction, and therefore it may interfere with the transcription of their genes. Because NF-kappaB is a major transcription factor involved in CAM expression, we studied its status in the 2'-hydroxychalcone treated cells. We demonstrate that 2'-hydroxychalcone inhibits the activation of NF-kappaB. These results have implications for using NF-kappaB inhibitors for the treatment of various inflammatory diseases.

Molecular mechanism of cGMP-mediated smooth muscle relaxation

Contraction and relaxation of smooth muscle is a tightly regulated process involving numerous endogenous substances and their intracellular second messengers. We examine the key role of cyclic guanosine monophosphate (cGMP) in mediating smooth muscle relaxation. We briefly review the current art regarding cGMP generation and degradation, while focusing on the recent identification of the molecular mechanisms underlying cGMP-mediated smooth muscle relaxation. cGMP-induced SM relaxation is mediated mainly by cGMP-dependent protein kinase activation. It involves several molecular events culminating in a reduction in intracellular Ca(2+) concentration and a decrease in the sensitivity of the contractile system to Ca(2+). We propose that the cGMP-induced decrease in Ca(2+) sensitivity is a strategic way to achieve "active relaxation" of the smooth muscle. In summary, we present compelling evidence supporting a key role for cGMP as a mediator of smooth muscle relaxation in physiological and pharmacological settings.

Antioxidant properties of butein isolated from Dalbergia odorifera

The antioxidant properties of butein, isolated from Dalbergia odorifera T. Chen, were investigated in this study. Butein inhibited iron-induced lipid peroxidation in rat brain homogenate in a concentration-dependent manner with an IC50, 3.3+/-0.4 microM. It was as potent as alpha-tocopherol in reducing the stable free radical diphenyl-2-picrylhydrazyl (DPPH) with an IC0.200, 9.2+/-1.8 microM. It also inhibited the activity of xanthine oxidase with an IC50, 5.9+/-0.3 microM. Besides, butein scavenged the peroxyl radical derived from 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH) in aqueous phase, but not that from 2,2-azobis(2, 4-dimethylvaleronitrile) (AMVN) in hexane. Furthermore, butein inhibited copper-catalyzed oxidation of human low-density lipoprotein (LDL), as measured by conjugated dienes and thiobarbituric acid-reactive substance (TBARS) formations, and electrophoretic mobility in a concentration-dependent manner. Spectral analysis revealed that butein was a chelator of ferrous and copper ions. It is proposed that butein serves as a powerful antioxidant against lipid and LDL peroxidation by its versatile free radical scavenging actions and metal ion chelation.

cGMP-elevating agents suppress proliferation of vascular smooth muscle cells by inhibiting the activation of epidermal growth factor signaling pathway

BACKGROUND

Abnormal proliferation of vascular smooth muscle cells (VSMC) is a key event in the pathogenesis of atherosclerosis and many vascular diseases. It is known that nitric oxide released from the endothelium participates in the regulation of VSMC proliferation via a cyclic 3',5'-guanosine monophosphate (cGMP)-mediated mechanism. In a series of experiments, sodium nitroprusside (SNP) and A02131-1 were evaluated for their antiproliferative effect and the mechanism of their cGMP-elevating action.

METHODS AND RESULTS

The effect of SNP and A02131-1 on epidermal growth factor (EGF)-stimulated proliferation of rat aortic smooth muscle cells (VSMC) was examined. Cell proliferation was measured in terms of [3H]thymidine incorporation, flow cytometry, and the cell number. Further, their effect on the EGF-activated signal transduction pathway was assessed by measuring mitogen-activated protein kinases (MAPK), MAPK kinase (MEK). Raf-1 activity, and the formation of active form of Ras. SNP and A02131-1 inhibited EGF-induced DNA synthesis and subsequent proliferation of VSMC. These two increased cGMP but only a little cAMP in VSMC. A similar antiproliferative effect was observed with 8-bromo-cGMP. The antiproliferative effect of the two was reversed by KT5823 but not by dideoxyadenosine nor Rp-cAMPS. SNP and A02131-1 blocked the EGF-inducible cell cycle progression at the G1/S phase. Further experiments indicated that the two cGMP-elevating agents primarily blocked the activation of Raf-1 by EGF-activated Ras.

CONCLUSIONS

These results demonstrate that cGMP-elevating agents inhibit [3H]thymidine incorporation and thus the growth of VSMC, and this inhibition appears to attenuate EGF-activated signal transduction pathway by preventing Ras-dependent activation of Raf-1.