Inhibitory effects of natural sesquiterpenoids isolated from the rhizomes of Curcuma zedoaria on prostaglandin E2 and nitric oxide production

Bioactive constituents and the molecular mechanism of Curcumae Rhizoma in the treatment of primary dysmenorrhea based on network pharmacology and molecular docking

BACKGROUND

Curcumae Rhizoma (CR) has a clinical efficacy in activating blood circulation to dissipate blood stasis and has been used for the clinical treatment of qi stagnation and blood stasis (QSBS) primary dysmenorrhea for many years. However, its molecular mechanism is unknown.

OBJECTIVE

The present study aimed to demonstrate the multicomponent, multitarget and multipathway regulatory molecular mechanisms of CR in the treatment of QSBS primary dysmenorrhea.

METHODS

Observations of pathological changes in uterine tissues and biochemical assays were used to confirm that a rat model was successfully established and that CR was effective in the treatment of QSBS primary dysmenorrhea. The main active components of CR in rat plasma were identified and screened by ultra-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UPLC-Q/TOF-MS). The component-target-disease network and protein-protein interaction (PPI) network of CR were constructed by a network pharmacology approach. Then, we performed Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Molecular docking was adopted to verify the interactions between the core components and targets of CR to confirm the accuracy of the network pharmacology prediction results. Furthermore, we evaluated the bioactive constituents of CR and molecular mechanism of by which CR promote blood circulation and remove blood stasis via platelet tests in vivo and in vitro and Western blot analysis.

RESULTS

The results of HE staining and biochemical assays of PGF2α, TXB2 and Ca2+ showed that CR was effective in the treatment of QSBS primary dysmenorrhea. A total of 36 active components were identified in CR, and 329 common targets were obtained and used to construct the networks. Of these, 14 core components and 10 core targets of CR in the treatment of primary dysmenorrhea were identified. The GO and KEGG enrichment analyses revealed that the common targets were involved in multiple signaling pathways, including the calcium, cAMP, MAPK, and PI3K-Akt signaling pathways, as well as platelet activation, which is closely related to platelet aggregation. The molecular docking results showed that the 14 core components and 10 core targets could bind spontaneously. Two core targets (MAPK1 and CCR5) and 7 core components (Isoprocurcumenol, Curcumadione, Epiprocurcumenol, (+)-Curdione, Neocurdione, Procurcumenol, and 13-Hydroxygermacrone) were closely related to CR in the treatment of primary dysmenorrhea. Furthermore, the in vivo platelet test showed that CR clearly inhibited platelet aggregation. Five core components ((+)-Curdione, Neocurdione, Isoprocurcumenol, Curcumadione and Procurcumenol) obviously inhibited platelet aggregation in vitro. In addition, based on the relationships among the signaling pathways, we confirmed that CR can effectively inhibit the expression of MAPK and PI3K-Akt signaling pathway-related proteins and decrease the protein expression levels of ERK, JNK, MAPK, PI3K, AKT and CCR5, thereby inhibiting platelet aggregation.

CONCLUSION

This study demonstrated the bioactive constituents and mechanisms of CR in promoting blood circulation and removing blood stasis and its multicomponent, multitarget and multipathway treatment characteristics in primary dysmenorrhea. The results provide theoretical evidence for the development and utilization of CR.

Bisabolane-type sesquiterpenoids from Curcuma longa L. exert anti-influenza and anti-inflammatory activities through NF-κB/MAPK and RIG-1/STAT1/2 signaling pathways

Influenza is a viral respiratory illness that causes seasonal epidemics and occasional pandemics. Disease severity may be contributed by influenza virus-induced cytokine dysregulation. The study was designed to investigate the isolation and identification of bisabolane-type sesquiterpenoids from Curcuma longa L., their antiviral and anti-inflammatory activities against H1N1 and their potential role in regulating host immune response in vitro. A pair of new bisabolane-type sesquiterpenoids, (6S,7S)-3-hydroxy-3-hydroxymethylbisabola-1,10-diene-9-one (18) together with seventeen known analogs (1-17), was isolated and elucidated from Curcuma longa L. Compounds 2, 11 and 14 could significantly inhibit A/PR/8/34 (H1N1) replication in MDCK cells, and compound 2 could significantly inhibit A/PR/8/34 (H1N1) replication in A549 cells. Compounds 4, 8, 9, 13 and 17 could markedly reduce pro-inflammatory cytokine (TNF-α, IL-6, IL-8 and IP-10) production at the mRNA and protein levels in A549 cells. Compound 4 regulated the levels of steroid biosynthesis, oxidative phosphorylation and protein processing in the endoplasmic reticulum, thereby inhibiting immune responses by proteomics analysis. Furthermore, compound 4 could inhibit the expression of p-NF-κB p65, NF-κB p65, IκBα, p-p38 MAPK, p-IκBα, RIG-1, STAT-1/2 and p-STAT-1/2 in the signaling pathways. These findings indicate that bisabolane-type sesquiterpenoids of C. longa could inhibit the expression of inflammatory cytokines induced by the virus and regulate the activity of NF-κB/MAPK and RIG-1/STAT-1/2 signaling pathways in vitro.

An Evidence-based Review of Medicinal Plants used in Traditional Persian Medicine for Treatment of Osteoarthritis

Osteoarthritis (OA) is known to be the leading cause of pain and disability in the elderly. The prevalence of this disease in adults over 60 years was 9.6% in men and 18% in women. The therapeutic goals of this disease generally include pain relief with the least side effects, improvement of articular function and improvement of life, in which pharmacological and nonpharmacological treatments are performed in different protocols. Due to the common side effects of pain relievers and complaints after invasive joint surgeries, there is a growing interest in the use of Traditional and Complementary protocols in OA treatment. In this paper, different sources of Traditional Persian Medicine (TPM) were searched to obtain any evidence evaluating any medicinal plants in the management of OA. Over 250 effective medicinal plants for the treatment of OA have been introduced in these sources, and by searching electronic databases including PubMed and Scopus, we have found that of these plants, 39 have direct or indirect evidence in the treatment of this complication by different mechanism of actions such as effect on Body mass index (BMI), obesity and dyslipidemia, anti-inflammatory, anti-nociceptive and antioxidant activity. The most important medicinal plants with direct evidence in the management of OA are Allium sativum, Commiphora mukul, Linum usitatissimum, Matricaria chamomilla, Nigella sativa, Zingiber officinale, and Piper nigrum. Medicinal plants seem to be a valuable source for discovering and identifying new drugs for treatment of OA; however, since most of the studies are preclinical, further clinical trials are required to achieve more conclusive results.

The protective effect of fermented Curcuma longa L. on memory dysfunction in oxidative stress-induced C6 gliomal cells, proinflammatory-activated BV2 microglial cells, and scopolamine-induced amnesia model in mice

BACKGROUND

Curcuma longa L. is a well-known medicinal plant that has been used for its anti-cancer, neuroprotective, and hepatoprotective effects. However, the neuroprotective effect of fermented C. longa (FCL) has not been reported. Therefore, in this study, the effectiveness of FCL for the regulation of memory dysfunction was investigated in two brain cell lines (rat glioma C6 and murine microglia BV2) and scopolamine-treated mice.

METHODS

C. longa powder was fermented by 5% Lactobacillus plantarum K154 containing 2% (w/v) yeast extract at 30 °C for 72 h followed by sterilization at 121 °C for 15 min. The protective effects of fermented C. longa (FCL) on oxidative stress induced cell death were analyzed by MTT assay in C6 cells. The anti-inflammatory effects of FCL were investigated by measuring the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) as well as the expression levels of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated BV2 cells. The step-through passive avoidance test, Morris water maze test, acetylcholinesterase (AChE) activity, and expression of cAMP response element-binding protein (CREB) and brain-derived neurotropic factor (BDNF) were employed to determine the effects of FCL on scopolamine-induced memory deficit in mice. The contents of curcuminoids were analyzed through LC/MS.

RESULTS

Pretreatment with FCL effectively prevented the cell death induced by oxidative stress in C6 cells. Moreover, FCL inhibited the production NO and PGE₂ via the inhibition of iNOS and COX-2 expression in BV2 cells. FCL significantly attenuated scopolamine-induced memory impairment in mice and prevented scopolamine-induced AChE activity in the hippocampus. Additionally, FCL reversed the reduction of CREB and BDNF expression. The curcuminoids content in FCL was 1.44%.

CONCLUSION

FCL pretreatment could alleviate scopolamine-induced memory impairment in mice, as well as oxidative stress and inflammation in C6 and BV2 cells, respectively. Thus, FCL might be a useful material for preventing impairment of learning and memory.

Molecular Hybridization-Guided One-Pot Multicomponent Synthesis of Turmerone Motif-Fused 3,3'-Pyrrolidinyl-dispirooxindoles via a 1,3-Dipolar Cycloaddition Reaction

Described herein is the development of a facile and efficient methodology for the synthesis of novel turmerone motif-fused 3,3′-pyrrolidinyl-dispirooxindoles 3–5 via a multicomponent 1,3-dipolar cycloaddition of dienones 2 with azomethine ylides (thermally generated in situfrom isatins and proline or thioproline or sarcosine). Products bearing four or three consecutive stereocenters consist of two oxindole moieties and a pyrrolidinyl core, including vicinal spiroquaternary stereocenters fused in one ring structure were smoothly obtained in high yields (up to 93% yield) with good diastereoselectivity (up to >20:1). Another valuable application of this method was for the design of new hybrid architectures for biological screening through the adequate fusion of these sub-units of turmerone and 3,3′-pyrrolidinyl-dispirooxindole, generating drug-like molecules.

Chemical constituents and biological research on plants in the genus Curcuma

Curcuma, a valuable genus in the family Zingiberaceae, includes approximately 110 species. These plants are native to Southeast Asia and are extensively cultivated in India, China, Sri Lanka, Indonesia, Peru, Australia, and the West Indies. The plants have long been used in folk medicine to treat stomach ailments, stimulate digestion, and protect the digestive organs, including the intestines, stomach, and liver. In recent years, substantial progress has been achieved in investigations regarding the chemical and pharmacological properties, as well as in clinical trials of certain Curcuma species. This review comprehensively summarizes the current knowledge on the chemistry and briefly discusses the biological activities of Curcuma species. A total of 720 compounds, including 102 diphenylalkanoids, 19 phenylpropene derivatives, 529 terpenoids, 15 flavonoids, 7 steroids, 3 alkaloids, and 44 compounds of other types isolated or identified from 32 species, have been phytochemically investigated. The biological activities of plant extracts and pure compounds are classified into 15 groups in detail, with emphasis on anti-inflammatory and antitumor activities.

A Western Primer of Chinese Herbal Therapy in Endometriosis and Infertility

Endometriosis is a disease that affects approximately 10% of all reproductive-aged women and the prevalence rises to 20–50% in infertile women. There is growing evidence that medicinal Chinese herbs with pain-alleviating and anti-inflammatory properties may be useful in the treatment of endometriosis and infertility, but the mechanisms of action of these herbs have yet to be investigated. In addition, studies of adequate design, sample size and appropriate control are lacking. Therefore, prospective randomized, controlled studies to evaluate the efficacy, mechanism of action and toxicities of Chinese herbs in the treatment endometriosis and infertility are needed.

Suppression of Inflammatory cytokine production by ar-Turmerone isolated from Curcuma phaeocaulis

Rhizomes of Curcuma phaeocaulis Valeton (Zingiberaceae) have traditionally been used for controlling inflammatory conditions. Numerous studies have aimed to isolate and characterize the bioactive constituents of C. phaeocaulis. It has been reported that its anti-inflammatory properties are a result of cyclooxygenase-2 inhibition; however, its effect on the T-cell function remains to be elucidated. In this study, four known sesquiterpenoids, viz., ar-turmerone (TM), germacrone (GM), (+)-(4S,5S)-germacrone-4,5-epoxide (GE), and curzerenone (CZ), were isolated from C. phaeocaulis rhizomes and evaluated for their effects on the CD4(+) T-cell function. While GM, GE, and CZ had no effect on the activation of splenic T cells or CD4(+) T cells, TM suppressed the interferon (IFN)-γ production, without affecting the interleukin (IL)-4 expression. TM also decreased the expression of IL-2 in CD4(+) T cells, but did not change their cell-division rates upon stimulation. These results suggest that TM, a major constituent of C. phaeocaulis rhizomes selectively exerts potent anti-inflammatory effects via suppression of the inflammatory cytokines IFN-γ and IL-2.

Curcumin-free turmeric exhibits anti-inflammatory and anticancer activities: Identification of novel components of turmeric

Turmeric, a dried powder derived from the rhizome of Curcuma longa, has been used for centuries in certain parts of the world and has been linked to numerous biological activities including antioxidant, anti-inflammatory, anticancer, antigrowth, anti-arthritic, anti-atherosclerotic, antidepressant, anti-aging, antidiabetic, antimicrobial, wound healing, and memory-enhancing activities. One component of turmeric is curcumin, which has been extensively studied, as indicated by more than 5600 citations, most of which have appeared within the past decade. Recent research has identified numerous chemical entities from turmeric other than curcumin. It is unclear whether all of the activities ascribed to turmeric are due to curcumin or whether other compounds in turmeric can manifest these activities uniquely, additively, or synergistically with curcumin. However, studies have indicated that turmeric oil, present in turmeric, can enhance the bioavailability of curcumin. Studies over the past decade have indicated that curcumin-free turmeric (CFT) components possess numerous biological activities including anti-inflammatory, anticancer, and antidiabetic activities. Elemene derived from turmeric is approved in China for the treatment of cancer. The current review focuses on the anticancer and anti-inflammatory activities exhibited by CFT and by some individual components of turmeric, including turmerin, turmerone, elemene, furanodiene, curdione, bisacurone, cyclocurcumin, calebin A, and germacrone.

Molecular mechanism underlying anti-inflammatory and anti-allergic activities of phytochemicals: an update

The resort worldwide to edible medicinal plants for medical care has increased significantly during the last few years. Currently, there is a renewed interest in the search for new phytochemicals that could be developed as useful anti-inflammatory and anti-allergic agents to reduce the risk of many diseases. The activation of nuclear transcription factor-kappa B (NF-κB) has now been linked to a variety of inflammatory diseases, while data from numerous studies underline the importance of phytochemicals in inhibiting the pathway that activates this transcription factor. Moreover, the incidence of type I allergic disorders has been increasing worldwide, particularly, the hypersensitivity to food. Thus, a good number of plant products with anti-inflammatory and anti-allergic activity have been documented, but very few of these compounds have reached clinical use and there is scant scientific evidence that could explain their mode of action. Therefore, this paper intends to review the most salient recent reports on the anti-inflammatory and anti-allergic properties of phytochemicals and the molecular mechanisms underlying these properties.

Inhibition of platelet aggregation by curdione from Curcuma wenyujin essential Oil

INTRODUCTION

Curdione, one of the major sesquiterpene compounds from Rhizoma Curcumae, has been shown to exhibit multiple bioactive properties. In this study, we investigated the anti-platelet aggregation and antithrombotic activities of curdione with different methods both in vitro and in vivo. The purpose of the study was to explore an inhibitor of platelet aggregation, which promised to be a preventive or therapeutic agent for various vascular diseases.

MATERIALS AND METHODS

Curdione was isolated from the essential oil of Curcuma wenyujin using the silica gel column chromatography method. The effects of curdione on human platelet aggregation induced by thrombin (0.3 U/ml), platelet-activating factor (PAF, 0.375 μg/ml), adenosine diphosphate (ADP, 10 μM) and arachidonic acid (AA, 0.1mg/ml) were tested in vitro, and the potential mechanisms underlying such activities were investigated. We also tested the antithrombotic effect of curdione in a tail thrombosis model.

RESULTS AND CONCLUSIONS

Curdione preferentially inhibited PAF- and thrombin- induced platelet aggregation in a concentration-dependent manner (IC(50): 60-80 μM), whereas much higher concentrations of curdione were required to inhibit platelet aggregation induced by ADP and AA. Curdione also inhibited P-selectin expression in PAF-activated platelets. Moreover, curdione caused an increase in cAMP levels and attenuated intracellular Ca(2+) mobilization in PAF-activated platelets. In vivo, we also found that curdione showed significant antithrombotic activity. Therefore, we conclude that the inhibitory mechanism of curdione on platelet aggregation may increase cAMP levels and subsequently inhibit intracellular Ca(2+) mobilization. Furthermore, the effect observed in the tail thrombosis model might be explained completely by increased vasodilation. These results indicate that curdione may be one of the main bioactive constituents in Rhizoma Curcumae that removes blood stasis.

Antitumour Effects of Isocurcumenol Isolated from Curcuma zedoaria Rhizomes on Human and Murine Cancer Cells

Curcuma zedoaria belonging to the family Zingiberaceae has been used in the traditional system of medicine in India and Southwest Asia in treating many human ailments and is found to possess many biological activities. The rationale of the present study was to isolate, identify, and characterize antitumour principles from the rhizomes of Curcuma zedoaria, to assess its cytotoxic effects on human and murine cancer cells, to determine its apoptosis inducing capacity in cancer cells, and to evaluate its tumour reducing properties in in vivo mice models. Isocurcumenol was characterized as the active compound by spectroscopy and was found to inhibit the proliferation of cancer cells without inducing significant toxicity to the normal cells. Fluorescent staining exhibited the morphological features of apoptosis in the compound-treated cancer cells. In vivo tumour reduction studies revealed that a dose of 35.7 mg/kg body weight significantly reduced the ascitic tumour in DLA-challenged mice and increased the lifespan with respect to untreated control mice.

Inhibition of inducible prostaglandin E2 production and cyclooxygenase-2 expression by curdione from Curcuma zedoaria

Overproduction of prostaglandins has been considered in mediation of inflammation and carcinogenic process. On this line, the inhibitors of prostaglandin biosynthetic enzyme cyclooxygenase (COX) have played a role of anti-inflammatory and cancer chemopreventive agents. In our continuous efforts to search anti-inflammatory and chemopreventive agents from natural products, bioassay-guided fractionation led to the isolation of curdione from the rhizome of Curcuma zedoaria with the inhibitory effect on the production of prostaglandin E2 in lipopolysaccharide (LPS)-stimulated mouse macrophage RAW 264.7 cells in a concentration-dependent manner (IC50 = 1.1 microM). Mechanistic studies suggest that the suppression of cyclooxygenase-2 (COX-2) mRNA expression is, at least in part, involved in this inhibitory activity of curdione.

Evolution of medical treatment for endometriosis: back to the roots?

Experimental evidence is accumulating to suggest that medicinal botanicals have anti-inflammatory and pain-alleviating properties and hold promise for treatment of endometriosis. Herein, we present a systematic review of clinical and experimental data on the use of medicinal herbs in the treatment of endometriosis. Although there is a general lack of evidence from clinical studies on the potential efficacy of medicinal herbs for the treatment of endometriosis-associated symptoms, our review highlights the anti-inflammatory and pain-alleviating mechanisms of action of herbal remedies. Medicinal herbs and their active components exhibit cytokine-suppressive, COX-2-inhibiting, antioxidant, sedative and pain-alleviating properties. Each of these mechanisms of action would be predicted to have salutary effects in endometriosis. Better understanding of the mechanisms of action, toxicity and herb-herb and herb-drug interactions permits the optimization of design and execution of complementary alternative medicine trials for endometriosis-associated pain. A potential benefit of herbal therapy is the likelihood of synergistic interactions within individual or combinations of plants. In this sense, phytotherapies may be analogous to nutraceuticals or whole food nutrition. We encourage the development of herbal analogues and establishment of special, simplified registration procedures for certain medicinal products, particularly herbal derivates with a long tradition of safe use.

Naturally occurring neuronal NO-synthase inactivators found in Nicotiana tabacum (Solanaceae) and other plants

NO-synthase (NOS) is a heme-containing enzyme that catalyzes the oxidation of L-arginine to nitric oxide, an important cellular signaling molecule. Recently, it was found that aqueous extracts of tobacco cigarettes cause the inactivation of the neuronal isoform of NOS (nNOS) and that this may explain some of the toxicological effects of smoking. Although the exact identity of the chemical inactivator(s) is not known, we wondered if extracts prepared from other plants, including those closely related to tobacco, Nicotiana tabacum (Solanaceae), would similarly inactivate nNOS. We examined 33 plants, representing diverse members of the plant kingdom ranging from whisk fern, Psilotum nudum (Psilotaceae) to tobacco and discovered 18 plants that contain a chemical inactivator(s) of nNOS. Of these plants, 16 are members of the core asterids flowering plant group. Of these asterids, 6 are members of the Solanaceae family, of which tobacco is a member. Based on the phylogenetic relationship of the plants, it is possible that the same chemical or related chemical inactivator(s) exist. This, in turn, may help elucidate the structure of the chemical(s), as well as provide a source of a potentially novel inactivator of nNOS. The alkaloid nicotine can be excluded as putative nNOS inhibitor.

The effect of turmeric extracts on inflammatory mediator production

Major compounds of several commonly used botanicals, including turmeric, have been purported to have anti-inflammatory actions. In order to test the anti-inflammatory activity of compounds isolated from rhizomes of Curcuma longa L. (Zingiberaceae), we have established an in vitro test system. HL-60 cells were differentiated and exposed to lipopolysaccharide (LPS) from Escherichia coli (1 microg/ml) in the presence or absence of botanical compounds for 24 h. Supernatants were collected and analyzed for the production of tumor necrosis factor alpha (TNF-alpha) and prostaglandin E2 (PGE2) using standard ELISA assays. Water-soluble extracts were not cytotoxic and did not exhibit biological activity. Organic extracts of turmeric were cytotoxic only at concentrations above 50 microg/ml. Crude organic extracts of turmeric were capable of inhibiting LPS-induced TNF-alpha (IC50 value = 15.2 microg/ml) and PGE2 (IC50 value = 0.92 microg/ml) production. Purified curcumin was more active than either demethoxy- or bisdemethoxycurcumin. Fractions and subfractions of turmeric extracts collected via preparative HPLC had differing biological activity, ranging from no activity to IC50 values of < 1 microg/ml. For some fractions, subfractionation resulted in a loss of activity, indicating interaction of the compounds within the fraction to produce an anti-inflammatory effect. A combination of several of the fractions that contain the turmeric oils was more effective than the curcuminoids at inhibiting PGE2. While curcumin inhibited COX-2 expression, turmeric oils had no effect on levels of COX-2 mRNA.

A curcuminoid and two sesquiterpenoids from Curcuma zedoaria as inhibitors of nitric oxide synthesis in activated macrophages

The overproduction of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) is known to be responsible for vasodilation and hypotension observed in septic shock and inflammation. Inhibitors of iNOS, thus, may be useful candidates for the treatment of inflammatory diseases accompanied by overproduction of NO. In the course of screening oriental anti-inflammatory herbs for the inhibitory activity of NO synthesis, a crude methanolic extract of Curcuma zedoaria exhibited significant activity. The activity-guided fractionation and repetitive chromatographic procedures with the EtOAc soluble fraction allowed us to isolate three active compounds. They were identified as 1,7-bis (4-hydroxyphenyl)-1,4,6-heptatrien-3-one (1), procurcumenol (2) and epiprocurcumenol (3) by spectral data analyses. Their concentrations for the 50% inhibition of NO production (IC50) in lipopolysaccharide (LPS)-activated macrophages were 8, 75, 77 microM, respectively. Compound 1 showed the most potent inhibitory activity for NO production in LPS-activated macrophages, while the epimeric isomers, compound 2 and 3 showed weak and similar potency. Inhibition of NO synthesis by compound 1 was very weak when activated macrophages were treated with 1 after iNOS induction. In the immunoblot analysis, compound 1 suppressed the expression of iNOS in a dose-dependent manner. In summary, 1,7-bis (4-hydroxyphenyl)-1,4,6-heptatrien-3-one from Curcuma zedoaria inhibited NO production in LPS-activated macrophages through suppression of iNOS expression. These results imply that the traditional use of C. zedoaria rhizome as anti-inflammatory drug may be explained at least in part, by inhibition of NO production.

Styrylheterocycles: a novel class of inhibitors on lipopolysaccharide-Induced nitric oxide production

A series of styrylheterocycles was prepared and their inhibitory activities against nitric oxide (NO) production were evaluated in a cell culture system using lipopolysaccharide-stimulated RAW264.7 macrophage cells. Our studies have identified a new series of inhibitors on NO production, providing the basis for further development of potent inhibitors. The preliminary structure-activity relationship, to elucidate the essential structural requirements, has been described. Mechanistic studies suggest that the suppression of iNOS mRNA transcription is, at least in part, related to the inhibitory activity of styrylheterocycles.