Protection by scoparone against the alterations of plasma lipoproteins, vascular morphology and vascular reactivity in hyperlipidaemic diabetic rabbit

Scoparone chemical modification into semi-synthetic analogues featuring 3-substitution for their anti-inflammatory activity

Natural products (NPs) continue to serve as a structural model for the development of new bioactive molecules and improve the process of identifying novel medicines. The biological effects of coumarins, one of the most researched compounds among NPs, are currently being thoroughly investigated. In the present investigation, we reported the synthesis of nineteen semi-synthetic 3-substituted scoparone analogues, followed by their characterization using analytical methods such as NMR, HPLC, and HRMS. All compounds screened for in vitro and in vivo study for their ability to reduce inflammation. The SAR study worked effectively for this particular scoparone 3-substitution, as compounds 3, 4, 9, 16, 18, and 20 displayed improved in vitro results for TNF-α than the parent molecule. Similarly, compounds 3, and 17 showed a higher percentage of IL-6 inhibition. Compounds 3, 4, and 12 have also been identified by in vivo studies as promising candidates with higher percent inhibition than the parent scoparone molecule. As evident from all in vitro and in vivo studies, compound 3 showed the most potent anti-inflammatory activity among all.

Scoparone alleviates Ang II-induced pathological myocardial hypertrophy in mice by inhibiting oxidative stress

Long‐term poorly controlled myocardial hypertrophy often leads to heart failure and sudden death. Activation of ras‐related C3 botulinum toxin substrate 1 (RAC1) by angiotensin II (Ang II) plays a pivotal role in myocardial hypertrophy. Previous studies have demonstrated that scoparone (SCO) has beneficial effects on hypertension and extracellular matrix remodelling. However, the function of SCO on Ang II‐mediated myocardial hypertrophy remains unknown. In our study, a mouse model of myocardial hypertrophy was established by Ang II infusion (2 mg/kg/day) for 4 weeks, and SCO (60 mg/kg bodyweight) was administered by gavage daily. In vitro experiments were also performed. Our results showed that SCO could alleviate Ang II infusion‐induced cardiac hypertrophy and fibrosis in mice. In vitro, SCO treatment blocks Ang II‐induced cardiomyocyte hypertrophy, cardiac fibroblast collagen synthesis and differentiation to myofibroblasts. Meanwhile, we found that SCO treatment blocked Ang II‐induced oxidative stress in cardiomyocytes and cardiac fibroblasts by inhibiting RAC1‐GTP and total RAC1 in vivo and in vitro. Furthermore, reactive oxygen species (ROS) burst by overexpression of RAC1 completely abolished SCO‐mediated protection in cardiomyocytes and cardiac fibroblasts in vitro. In conclusion, SCO, an antioxidant, may attenuate Ang II‐induced myocardial hypertrophy by suppressing of RAC1 mediated oxidative stress.

Artemisia scoparia and Metabolic Health: Untapped Potential of an Ancient Remedy for Modern Use

Botanicals have a long history of medicinal use for a multitude of ailments, and many modern pharmaceuticals were originally isolated from plants or derived from phytochemicals. Among these, artemisinin, first isolated from Artemisia annua, is the foundation for standard anti-malarial therapies. Plants of the genus Artemisia are among the most common herbal remedies across Asia and Central Europe. The species Artemisia scoparia (SCOPA) is widely used in traditional folk medicine for various liver diseases and inflammatory conditions, as well as for infections, fever, pain, cancer, and diabetes. Modern in vivo and in vitro studies have now investigated SCOPA's effects on these pathologies and its ability to mitigate hepatotoxicity, oxidative stress, obesity, diabetes, and other disease states. This review focuses on the effects of SCOPA that are particularly relevant to metabolic health. Indeed, in recent years, an ethanolic extract of SCOPA has been shown to enhance differentiation of cultured adipocytes and to share some properties of thiazolidinediones (TZDs), a class of insulin-sensitizing agonists of the adipogenic transcription factor PPARγ. In a mouse model of diet-induced obesity, SCOPA diet supplementation lowered fasting insulin and glucose levels, while inducing metabolically favorable changes in adipose tissue and liver. These observations are consistent with many lines of evidence from various tissues and cell types known to contribute to metabolic homeostasis, including immune cells, hepatocytes, and pancreatic beta-cells. Compounds belonging to several classes of phytochemicals have been implicated in these effects, and we provide an overview of these bioactives. The ongoing global epidemics of obesity and metabolic disease clearly require novel therapeutic approaches. While the mechanisms involved in SCOPA's effects on metabolic, anti-inflammatory, and oxidative stress pathways are not fully characterized, current data support further investigation of this plant and its bioactives as potential therapeutic agents in obesity-related metabolic dysfunction and many other conditions.

Inhibitory effects of scoparone from chestnut inner shell on platelet-derived growth factor-BB-induced vascular smooth muscle cell migration and vascular neointima hyperplasia

BACKGROUND

Compounds of the inner shell of chestnut (Castanea crenata) have diverse biological activities, including anti-cancer and anti-oxidant activities. Here we explored the effects of an extract of chestnut inner shells and of its bioactive component scoparone on vascular smooth muscle cell migration and vessel damage.

RESULTS

The ethanol extract of chestnut inner shells, containing 11 major compounds, inhibited platelet-derived growth factor (PDGF)-BB-induced migration of rat aortic smooth muscle cells (RASMCs). Among these compounds, scoparone (6,7-dimethoxycoumarin) suppressed RASMC migration and wound healing in response to PDGF-BB but did not affect RASMC proliferation. In RASMCs, scoparone inhibited the PDGF-BB-induced rat aortic sprout outgrowth and attenuated the PDGF-BB-mediated increase in phosphorylation of mitogen-activated protein kinases (MAPKs), p38 MAPK and extracellular signal-regulated kinase 1/2. The in vivo administration of scoparone resulted in the attenuation of neointima formation in balloon-injured carotid arteries of rats.

CONCLUSION

These findings demonstrate that scoparone, found in chestnut inner shells, may inhibit cell migration through suppression of the phosphorylation of MAPKs in PDGF-BB-treated RASMCs, probably contributing to the reduction of neointimal hyperplasia induced after vascular injury. Therefore, scoparone and chestnut inner shell may be a potential agent or functional food, respectively, for the prevention of vascular disorders such as vascular restenosis or atherosclerosis. © 2019 Society of Chemical Industry.

Protective effects of scoparone against ischemia‑reperfusion‑induced myocardial injury

The present study aimed to investigate the protective effects and molecular mechanisms of scoparone on ischemia‑reperfusion (I/R) injury in primary cultured cardiac myocytes and rats. An in vivo rat model of I/R injury and an in vitro primary cultured cardiac myocyte model of oxygen‑glucose deprivation/reoxygenation were used to investigate the protective effects of scoparone. Cell viability, lactate dehydrogenase (LDH) release, superoxide dismutase (SOD), creatine kinase (CK) and malondialdehyde (MDA) levels, and reactive oxygen species (ROS) production were subsequently measured. In addition, cell apoptosis was assessed by terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling staining, and myocardial infarct area (IA) was determined by triphenyl tetrazolium chloride staining. Furthermore, the protein expression levels of B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (Bax), cytochrome c (Cyt C) and caspase‑3 were assessed by western blotting. The results demonstrated that treatment with scoparone markedly increased cell viability, SOD levels and Bcl‑2 protein expression, and decreased LDH release, MDA production, CK levels, ROS concentration, cell apoptotic rate, myocardial IA, and Bax, caspase‑3 and Cyt C protein expression. These findings indicated that scoparone may have a protective effect against I/R injury, thus suggesting that scoparone may be a considered a potential drug for the treatment of I/R injury via the inhibition of oxidative stress and cell apoptosis.

Therapeutic effects of scoparone on pilocarpine (Pilo)-induced seizures in mice

Epilepsy is a common and devastating neurological disorder. Inflammatory processes and apoptosis in brain tissue have been reported in human epilepsy. Scoparone (6,7-dimethoxycoumarin) is an important chemical substance, which has multiple beneficial activities, including antitumor, anti-inflammatory and anti-coagulant properties. In our present study, we attempted to investigate if scoparone could attenuate seizures-induced blood brain barrier breakdown, inflammation and apoptosis. Pilocarpine (Pilo) and methylscopolamine were used to establish acute seizure animal model. Scoparone suppressed the leakage of blood brain barrier, inflammation and apoptosis. In hippocampus and cortex, the expression of inflammation-associated molecules, such as chemokine (CXC motif) ligand 1 (CXCL-1), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-6, hypoxia-inducible factor 1α (HIF-1α), and monocyte chemoattractant protein-1 (MCP-1), were reduced by scoparone through inactivating toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-κB) pathway. Scoparone reduced apoptotic levels in hippocampus by TUNEL analysis, along with decreased Caspase-3 and PARP cleavage. In addition, phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway in Pilo-induced acute seizures was also inactivated by scoparone. In vitro, we confirmed that scoparone inhibited LPS-caused astrocytes activation as proved by the reduced glial fibrillary acidic protein (GFAP) levels, inflammation and apoptosis, which were at least partly dependent on AKT suppression. The results above indicated that scoparone could relieve pilocarpine (Pilo)-induced seizures against neural cell inflammation and apoptosis.

Scoparone Inhibits LPS-Simulated Inflammatory Response by Suppressing IRF3 and ERK in BV-2 Microglial Cells

Microglia activation and the release of various inflammatory cytokines are largely related to neurological diseases, including Parkinson’s, Alzheimer’s, and other brain diseases. The suppression of microglial cells using natural bioactive compounds has become increasingly important for brain therapy owing to the expected beneficial effect of lower toxicity. Scoparone (6,7-dimethoxycoumarin), a major bioactive compound found in various plant parts, including the inner shell of chestnut (Castanea crenata), was evaluated on lipopolysaccharide (LPS)-activated BV-2 microglia cells. The results indicated that scoparone suppresses the LPS-stimulated increase of neuroinflammatory responses and inhibited the pro-inflammatory cytokine production in the BV-2 microglial cells. A mechanistic study showed that scoparone specifically inhibited the LPS-stimulated activation via a major regulation of IRF-3 and a regulation of ERK, whereby the phosphorylation in the BV-2 microglial cells is blocked. These data suggest that scoparone has anti-neuroinflammatory effects in LPS-activated BV-2 microglial cells, and could possibly be used in the development of novel drugs for the prevention and treatment of neuroinflammatory diseases.

Influence of coumarin and some coumarin derivatives on serum lipid profiles in carbontetrachloride-exposed rats

In the present study, coumarin and some coumarin derivatives (esculetin, scoparone, and 4-methylumbelliferone) were investigated for their lipid-lowering effect in rats. Male Sprague–Dawley rats (150–200 g) were divided into six groups and each group comprised of five rats. Hepatic injury-dependent hyperlipidemia was induced by carbon tetrachloride (CCl4, 1.25 ml/kg). Coumarin and coumarin derivatives esculetin (35 mg/kg), scoparone (35 mg/kg), 4-methylumbelliferone (35 mg/kg), or coumarin (30 mg/kg) were administered to experimental groups at 12-h intervals. Animals received the derivatives esculetin, scoparone or 4-methylumbelliferone prior to the administration of a single toxic dose of CCl4. Serum total cholesterol (TC), triglyceride (TG), very low-density lipoprotein cholesterol (VLDL-C), and low-density lipoprotein cholesterol (LDL-C) levels significantly increased in CCl4-treated group ( p < 0.05, p < 0.01, p < 0.01, and p < 0.05, respectively), while levels of serum high-density lipoprotein cholesterol (HDL-C) decreased ( p < 0.01). 4-Methylumbelliferone had no recovery effects on serum TC levels, however, significantly prevented CCl4-induced hyperlipidemia by reducing TG and VLDL-C levels ( p < 0.05 and p < 0.05, respectively). In addition, coumarin had no recovery effect on any of the serum lipid parameters against CCl4-induced hyperlipidemia. Among the coumarin derivatives only esculetin and scoparone significantly prevented serum HDL-C in CCl4-induced dyslipidemia. The results from this study indicate that the chemical structure of coumarins plays an important role on the regulation of serum lipid profiles.

Hybrids of coumarin–indole: design, synthesis and biological evaluation in Triton WR-1339 and high-fat diet induced hyperlipidemic rat models

Lipid lowering activity of novel coumarin–indole hybrids has been demonstrated.

Scoparone interferes with STAT3-induced proliferation of vascular smooth muscle cells

Scoparone, which is a major constituent of Artemisia capillaries, has been identified as an anticoagulant, hypolipidemic, vasorelaxant, anti-oxidant and anti-inflammatory drug, and it is used for the traditional treatment of neonatal jaundice. Therefore, we hypothesized that scoparone could suppress the proliferation of VSMCs by interfering with STAT3 signaling. We found that the proliferation of these cells was significantly attenuated by scoparone in a dose-dependent manner. Scoparone markedly reduced the serum-stimulated accumulation of cells in the S phase and concomitantly increased the proportion of cells in the G0/G1 phase, which was consistent with the reduced expression of cyclin D₁, phosphorylated Rb and survivin in the VSMCs. Cell adhesion markers, such as MCP-1 and ICAM-1, were significantly reduced by scoparone. Interestingly, this compound attenuated the increase in cyclin D promoter activity by inhibiting the activities of both the WT and active forms of STAT3. Similarly, the expression of a cell proliferation marker induced by PDGF was decreased by scoparone with no change in the phosphorylation of JAK2 or Src. On the basis of the immunofluorescence staining results, STAT3 proteins phosphorylated by PDGF were predominantly localized to the nucleus and were markedly reduced in the scoparone-treated cells. In summary, scoparone blocks the accumulation of STAT3 transported from the cytosol to the nucleus, leading to the suppression of VSMC proliferation through G1 phase arrest and the inhibition of Rb phosphorylation. This activity occurs independent of the form of STAT3 and upstream of kinases, such as Jak and Src, which are correlated with abnormal vascular remodeling due to the presence of an excess of growth factors following vascular injury. These data provide convincing evidence that scoparone may be a new preventative agent for the treatment of cardiovascular diseases.

Recent Studies and Progression of Yin Chen Hao ( Yīn Chén Hāo), a Long-term Used Traditional Chinese Medicine

Yin Chen Hao (Artemisia capillaris Thunb; 茵陳蒿 Yīn Chén Hāo) is a traditional Chinese medicine for treating hepatic disorders. This review provides recent pharmacological studies of Yin Chen Hao as well as some chemical constituents isolated from Yin Chen.

Scoparone exerts anti-tumor activity against DU145 prostate cancer cells via inhibition of STAT3 activity

Scoparone, a natural compound isolated from Artemisia capillaris, has been used in Chinese herbal medicine to treat neonatal jaundice. Signal transducer and activator of transcription 3 (STAT3) contributes to the growth and survival of many human tumors. This study was undertaken to investigate the anti-tumor activity of scoparone against DU145 prostate cancer cells and to determine whether its effects are mediated by inhibition of STAT3 activity. Scoparone inhibited proliferation of DU145 cells via cell cycle arrest in G1 phase. Transient transfection assays showed that scoparone repressed both constitutive and IL-6-induced transcriptional activity of STAT3. Western blot and quantitative real-time PCR analyses demonstrated that scoparone suppressed the transcription of STAT3 target genes such as cyclin D1, c-Myc, survivin, Bcl-2, and Socs3. Consistent with this, scoparone decreased phosphorylation and nuclear accumulation of STAT3, but did not reduce phosphorylation of janus kinase 2 (JAK2) or Src, the major upstream kinases responsible for STAT3 activation. Moreover, transcriptional activity of a constitutively active mutant of STAT3 (STAT3C) was inhibited by scoparone, but not by AG490, a JAK2 inhibitor. Furthermore, scoparone treatment suppressed anchorage-independent growth in soft agar and tumor growth of DU145 xenografts in nude mice, concomitant with a reduction in STAT3 phosphorylation. Computational modeling suggested that scoparone might bind the SH2 domain of STAT3. Our findings suggest that scoparone elicits an anti-tumor effect against DU145 prostate cancer cells in part through inhibition of STAT3 activity.

Evaluation of the hypolipidemic activity of 6,7-dimethoxycoumarin on placental tissue factor mRNA expression in experimental anti-phospholipid syndrome

Background:

Anti-phospholipid syndrome is a thrombogenic and systemic autoimmune disorder that influences fetal life throughout gestation period. Over expression of tissue factor on the surface of monocyte(s) is reported to be a major causative agent in inducing anti-phospholipid antibody-mediated placental thrombosis and fetal loss in pregnant women. The over expression of tissue factor is proposed to be due to high levels of blood cholesterol and oxidized lipoproteins.

Objective:

In this study, we report the lipid-lowering property and anti-tissue factor activity of one of the naturally occurring coumarin derivates 6,7-dimethoxycoumarin, found aplenty in Chinese medicinal plant Artemisia scoparia, and its effect on tissue factor mRNA expression in experimental anti-phospholipid syndrome.

Materials and Methods:

Adult female mice were immunized with cardiolipin and beta-2-glycoprotein-1 to induce experimental anti-phospholipid syndrome. Female mice with high titer of aCL were allowed to mate with male, and the female mice were treated with 6,7-dimethoxycoumarin on a daily dose of 5 mg/kg body weight from day 3 to day 15 of gestation. On day 18 of pregnancy, all the animals were dissected to measure biochemical parameters in blood, and TF mRNA expression levels were measured in placenta.

Results:

Treatment with 6,7-dimethoxycoumarin significantly reduced the levels of cholesterol and plasma lipids by its potent hypolipidemic property, which eventually reduced the over-expression tissue factor at mRNA levels in placenta. We believe that further studies in animal model would reveal the potential therapeutic properties of 6,7-dimethoxycoumarin against anti-phospholipid syndrome.

Conclusion:

The 6,7-dimethoxycoumarin is capable to reduce the expression of TF in placenta at the mRNA level and thrombus generation indirectly by its potent anti-TF and anti-oxidant activities.

Anti-obesity effect of Artemisia capillaris extracts in high-fat diet-induced obese rats

This study evaluated the anti-obesity effects of Artemisia capillaris extracts in high-fat diet (HFD)-induced obese rats. After six weeks feeding with HFD, Wistar male rats (12-weeks-old) were divided into three groups: HFD-control group and HFD mixed with 0.4% and 0.8% Artemisia capillaris extracts treated groups. After seven weeks of treatments, the body weight gain of the 0.4% and 0.8% A. capillaris extracts treated groups were significantly less than that of the HFD-control group by 11.8% and 15.4%, respectively. Also, A. capillaris extracts treated groups showed significantly lower serum TG, TC and LDL-c levels in a dose-related manner, while causing the reverse effect in serum HDL-c, and exhibited a hepatoprotective effects in vivo, indicated by reduced hepatic lipid contents, and serum ALT and AST levels. These results show that A. capillaris extracts may prevent body weight increases and improve dyslipidemia in HFD-induced obese rats by enhancing their lipid metabolism.

Hypolipidaemic Effect of Hericium erinaceum Grown in Artemisia capillaris on Obese Rats

In this study, ethanolic extracts from Hericium erinaceum cultivated with Artemisia capillaris (HEAC) were assessed for their ability to lower the cholesterol levels of male Sprague-Dawley rats fed a high-fat diet. Rats were randomly subdivided into seven test groups. Each group contained eight rats fed a high-fat diet during a growth period lasting 4 wk. Supplementation with the extracts was performed once a day for 2 wk after the high-fat diet. The control group (rats fed a high-fat diet) showed a high efficiency ratio (feed efficiency ratio) value compared to the normal group. Biochemical parameters, including total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-c), and triglyceride (TG) levels dramatically increased in the control group compared to the normal group. High-density lipoprotein-cholesterol (HDL-c) content in the control group was also significantly lower relative to the normal group. Two positive control groups, treated with simvastatin and atorvastatin, had lowered TC, LDL-c, and TG levels, and increased HDL-c content compared to the control group. Treatment with the tested extracts, including HEAC, ethanolic extracts from Hericium erinaceum, and ethanolic extracts from Artemisia capillaris reduced TC, LDL-c, and TG levels and elevated HDL-c content in the hyperlipidemia rats. The atherogenic index and cardiac risk factor values for the HEAC-treated group were 0.95 and 1.95, respectively. Simvastatin- and atorvastatin-treated groups showed atherogenic index values of 1.56 and 1.69, respectively, and cardiac risk factor values of 2.56 and 2.69, respectively. These results show HEAC possesses an ability to cure hyperlipidemia in rats and may serve as an effective natural medicine for treating hyperlipidemia in humans.

Short- and long-term regulation of 3-hydroxy 3-methylglutaryl coenzyme A reductase by a 4-methylcoumarin

Dyslipidemia is one of the most significant risk factors for cardiovascular diseases. Cholesterol homeostasis is regulated by both the receptor-mediated endocytosis of Low Density Lipoproteins by LDL receptors and de novo cholesterol synthesis via the rate-limiting enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase. Although statins, 3-hydroxy-3-methylglutaryl coenzyme A reductase substrate competitors, have revolutionized the management of cardiovascular diseases by lowering serum LDL, their side effects range from myalgia to rhabdomyolysis. Treatment with antioxidant compounds could represent an efficient alternative in the modulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. Indeed it has already been demonstrated that the rise in reactive oxygen species levels causes the complete dephosphorylation and, in turn activation of the enzyme. Many coumarins and their derivatives have the special ability to scavenge reactive oxygen species or show a lipid lowering potential. Here we evaluated whether the coumarin, 4-methylesculetin could exert both the ability to scavenge ROS and to modulate 3-hydroxy-3-methylglutaryl coenzyme A reductase in HepG2 cell line where the enzyme activity dysregulation induced by reactive oxygen species has already been reported. The antioxidant property of 4-methylesculetin led to the reduction of 3-hydroxy-3-methylglutaryl coenzyme A reductase activation state through the increase of the enzyme phosphorylation. In addition, this coumarin showed the ability to modulate 3-hydroxy-3-methylglutaryl coenzyme A reductase protein levels both by transcriptional and degradational events independent of its antioxidant activity.

Artemisia capillaris inhibits lipid accumulation in 3T3-L1 adipocytes and obesity in C57BL/6J mice fed a high fat diet

The purpose of the current study was to determine the effect of the Artemisia capillaris ethyl acetate (ACE) fraction on diet-induced obesity and to elucidate the underlying mechanism. The ACE fraction treatment decreased the leptin level and fat accumulation in cultured 3T3-L1 adipocytes through the free fatty acids released in the medium. The ACE fraction significantly suppressed the expression of peroxisome proliferator-activated receptor-gamma in cultured 3T3-L1 adipocytes. To determine the effect of the ACE fraction on C57BL/6J male mice, the mice were separated into six groups: normal control (N), N plus 0.1 g/kg body weight ACE (NB), high fat control group (HF), HF plus 0.05 g/kg of body weight ACE (HFA), HF plus 0.1 g/kg of body weight ACE (HFB), and HF plus 0.03 g/kg of body weight rosiglitazone (RG) groups. We speculate that the HFB group exhibits a lipid-lowering effect via increased mitochondrial beta-oxidation, of which the rate-limiting enzyme is carnitine palmitoyl transferase I, the activity of which was significantly increased. Also, the activity of fatty acid synthase, a key enzyme of fatty acid synthesis, was markedly suppressed (19%) in the HFB group, as compared to the HF group, and glycerol-3-phosphate dehydrogenase activity, which is very useful in studying adipogenic differentiation in vitro, was markedly suppressed (30%) in the HFB group compared with the HF group. Furthermore, the HFB group showed lowered hepatic lipid droplet accumulation and adipose tissue weight and size. We suggest that 0.1 g of the ACE fraction/kg of body weight may exert an anti-obesity effect in C57BL/6J mice by enhancing lipid metabolism.

Anti-allergic effects of scoparone on mast cell-mediated allergy model

Scoparone is known to have a wide range of pharmacological properties in vitro. However, the roles of scoparone in immediate-type allergic reactions have not yet been investigated. In this study, we demonstrated that scoparone attenuated IgE-mediated allergic response in mast cells. Oral administration of scoparone inhibited passive cutaneous anaphylaxis in rats. Presence of scoparone dose-dependently decreased histamine release from rat peritoneal mast cells (RPMC) stimulated by anti-dinitrophenyl IgE. Moreover, scoparone reduced the expression and secretion of pro-inflammatory cytokines, such as tumor necrosis factor-alpha and interleukin-6 in RPMC. Pretreatment with scoparone inhibited the calcium uptake and p38 mitogen-activated protein kinase (MAPK) activity. Furthermore, scoparone blocked translocation of nuclear factor-kappa B (NF-kappaB) p65 subunit by suppressing IkappaBalpha phosphorylation in RPMC. Reduced calcium uptake as well as the suppressed activity of p38 MAPK and NF-kappaB might be involved in the inhibitory effect of scoparone on the secretory response. Our findings suggest that scoparone may serve as an effective therapeutic agent for allergic diseases.

New coumarin-based anti-inflammatory drug: putative antagonist of the integrins alphaLbeta2 and alphaMbeta2

This study was conducted to investigate putative antagonism of integrin receptors alphaMbeta2 and alphaLbeta2 by a novel coumarin derivative (BOL-303225-A), its efficacy in-vivo after retinal ischaemia-reperfusion injury, and its bioavailability in rat plasma. A cellular adhesion assay in Jurkat and U937 cells, and a flow cytometry assay with an antibody against the beta2 subunit were conducted. BOL-303225-A bioavailability in rat plasma and the retinal levels of myeloperoxidase (MPO) after ischaemia-reperfusion injury were evaluated after oral administration (10 mg kg(-1)). In-vitro cell viability assays revealed no cytotoxicity for BOL-303225-A over a wide dose range, and IC50 values of 32.3 +/- 1.5 muM and 84.95 +/- 2.3 muM were found for Jurkat and U937 cells, respectively. The drug showed specific binding to the alphaMbeta2 and alphaLbeta2 integrin receptors expressed by U937 and Jurkat cells, respectively, producing a fluorescence shift towards lower values in a concentration-dependent manner. The pharmacokinetic profile of BOL-303225-A exhibited rapid absorption following oral administration in the rat. A significant reduction of retinal MPO levels was observed in drug-treated rats. This study demonstrated that BOL-303225-A acts as an antagonist of the integrin alphaLbeta2 and alphaMbeta2 receptors, suggesting that this drug could be used for ocular diseases such as diabetic retinopathy.

Development of a rapid and validated method for investigating the metabolism of scoparone in rat using ultra-performance liquid chromatography/electrospray ionization quadruple time-of-flight mass spectrometry

Scoparone (6,7-dimethoxycoumarin) is known to have a wide range of pharmacological properties. In this study, a rapid and validated ultra-performance liquid chromatography/electrospray ionization quadruple time-of-flight mass spectrometry (UPLC/ESI-QTof-MS) method was developed to investigate the metabolism of scoparone in rat for the first time. The new method reduced the sample handling and analytical time by three- to six-fold, and the detection limit by five- to 1000-fold, compared to published methods. Far more metabolites were detected and identified compared to published data, which were preliminarily identified as scopoletin, isoscopoletin, isofraxidin, and fraxidin, respectively, when subjected to tandem mass spectrometry analyses. It is found that the metabolic trajectory of scoparone in rat focused on phase I metabolism which is obviously different from published results, and revealed a wide range of pharmacological properties of scoparone partly attributed to the bioactivities of its metabolites.

Inhibition of Cytokine-Mediated Nitric Oxide Synthase Expression in Rat Insulinoma Cells by Scoparone

Cytokines produced by immune cells infiltrating pancreatic islets are important mediators of beta-cell destruction in insulin-dependent diabetes mellitus. Scoparone (6,7-dimethoxycoumarin) is known to have a wide range of pharmacological properties in vitro. In this study, the effects of scoparone on cytokine-induced beta-cell dysfunction were examined. Presence of scoparone significantly protected interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma)-mediated cytotoxicity of RINm5F, a rat insulinoma cell line, and preserved glucose-stimulated insulin secretion in rat pancreatic islets. Scoparone also resulted in a significant reduction in IL-1beta and IFN-gamma-induced nitric oxide (NO) production, a finding that correlated well with reduced levels of the inducible form of NO synthase (iNOS) mRNA and protein. The molecular mechanism by which scoparone inhibited iNOS gene expression appeared to involve the inhibition of NF-kappaB activation. These results revealed the possible therapeutic value of scoparone for the prevention of diabetes mellitus progression.

Stimulation of melanogenesis by scoparone in B16 melanoma cells

AIM

The effect of coumarin derivatives on melanogenesis was investigated in B16 murine melanoma cells.

METHODS

Melanin content and tyrosinase activity were analyzed spectrophotometrically. The expression of tyrosinase, tyrosinase-related protein-1 (TRP-1) and tyrosinase-related protein-2 (TRP-2) were measured either by reverse transcription-polymerase chain reaction (RT-PCR) or Western blot.

RESULTS

Among the coumarin derivatives studied, scoparone (6,7- dimethoxycoumarin) was the most potent; the 6- or 7-methoxy group was found to be essential for the stimulation of melanogenesis. The melanin content was greatly increased by scoparone in a dose-dependent manner; there was no cytotoxicity at the effective concentrations. Scoparone increased enzyme activity as well as protein and mRNA expression of tyrosinase. In addition, mRNA of TRP-1 and TRP-2 were also increased after treatment with scoparone. H-89, an inhibitor of protein kinase A (PKA), completely inhibited the scoparone-induced increase of melanogenesis and the tyrosinase protein.

CONCLUSION

These results suggest that scoparone-induced stimulation of melanogenesis is likely to occur at the transcriptional level of melanogenesis-related enzymes through PKA signaling.

Antihyperglycemic activity of Tarralin, an ethanolic extract of Artemisia dracunculus L

The studies reported here were undertaken to examine the antihyperglycemic activity of an ethanolic extract of Artemisia dracunculus L., called Tarralin in diabetic and non-diabetic animals. In genetically diabetic KK-A(gamma) mice, Tarralin treatment by gavage (500 mg/kg body wt./day for 7 days) lowered elevated blood glucose levels by 24% from 479+/-25 to 352+/-16 mg/dl relative to control animals. In comparison, treatment with the known antidiabetic drugs, troglitazone (30 mg/kg body wt./day) and metformin (300 mg/kg body wt./day), decreased blood glucose concentrations by 28% and 41%, respectively. Blood insulin concentrations were reduced in the KK-A(gamma) mice by 33% with Tarralin, 48% with troglitazone and 52% with metformin. In (STZ)-induced diabetic mice, Tarralin treatment, (500 mg/kg body wt./day for 7 days), also significantly lowered blood glucose concentrations, by 20%, from 429+/-41 to 376+/-58 mg/dl relative to control. As a possible mechanism, Tarralin was shown to significantly decrease phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression by 28% in STZ-induced diabetic rats. In non-diabetic animals, treatment with Tarralin did not significantly alter PEPCK expression, blood glucose or insulin concentrations. The extract was also shown to increase the binding of glucagon-like peptide (GLP-1) to its receptor in vitro. These results indicate that Tarralin has antihyperglycemic activity and a potential role in the management of diabetic states.

Effects of rosuvastatin on nitric oxide-dependent function in aorta and corpus cavernosum of diabetic mice: relationship to cholesterol biosynthesis pathway inhibition and lipid lowering

Elevated plasma lipids contribute to neurovascular dysfunction in diabetes. Statins have lipid-lowering properties and can modulate endothelial nitric oxide (NO) bioavailability. The aim was to assess the impact of these factors on autonomic nitrergic nerve and endothelial function. Thus, the effects of diabetes and treatment with the HMG-CoA reductase inhibitor rosuvastatin (RSV) were examined on corpus cavernosum and aorta from streptozotocin-induced diabetic mice in a 4-week prevention study and a 2-week intervention study, following 4 weeks of untreated diabetes. Cotreatment with mevalonate was used to assess the dependence of RSV's effects on HMG-CoA reductase blockade. Diabetes caused a 25% reduction in NO-mediated endothelium-dependent relaxation to acetylcholine for aorta and cavernosum. Relaxations of cavernosum were in the nondiabetic range following prevention or reversal treatment. The aortic deficit was completely prevented and 60% reversed by RSV. Maximum NO-dependent nonadrenergic, noncholinergic nerve-mediated relaxations of cavernosum were reduced 25-33% by diabetes. RSV treatment prevented 75% and reversed 71% of this diabetic deficit. Cotreatment with mevalonate inhibited the beneficial actions of RSV on aorta and cavernosum. Total plasma cholesterol was unaltered by diabetes or treatment. Thus, RSV corrected defective NO-mediated nerve and vascular function in diabetic mice independent of cholesterol lowering but via effects dependent on cholesterol biosynthesis pathway inhibition.

Pharmacokinetics of a novel anti-asthmatic, scoparone, in the rabbit serum assessed by a simple HPLC method

The pharmacokinetics of scoparone (Sco), an anti-asthmatic coumarin derivative extracted from the traditional Chinese herb "Yin Chen", was determined in rabbit plasma by a high performance liquid chromatography (HPLC) method which was newly developed using a Nova-Pak Silica C(18) column and a mobile phase of acetonitrile-water (20:80, v/v). After intravenous administration of Sco at a dose of 2.0 or 3.6 mg/kg, the time course of the plasma concentration of Sco was found to fit an open two-compartment model. AUC values increased, dose-dependently. Mean T(1/2) values showed that half-life was dosage independent. Distribution and elimination of Sco in rabbit plasma were both relatively rapid. These results indicate that Sco could be easily administrated by spray inhalers and is expected to have few associated side effects.

A quantitative study of the aorta of the New Zealand rabbit (Oryctolagus cuniculus L.)

Ten segments of the aorta of the rabbit were studied quantitatively. The thoracic and abdominal aorta of the rabbit were measured from proximal to distal and parallel to the reduced diameter, demonstrating a decreasing thickness of the tunica intima and tunica media that becomes physiologically apparent during adulthood in these commonly used laboratory animals. The ratio of intimal to medial thickness, multiplied by 100, was calculated and found to be between 2.56 and 3.74 for the thoracic aorta and 4.03 and 5.62 for the abdominal aorta of the rabbit. These findings are important for the better understanding of the development of atherosclerosis.

Pharmacological and biochemical actions of simple coumarins: natural products with therapeutic potential

1. More than 300 coumarins have been identified from natural sources, especially green plants. The pharmacological and biochemical properties and therapeutic applications of simple coumarins depend upon the pattern of substitution. More complex related compounds based on the coumarin nucleus include the dicoumarol/warfarin anticoagulants, aflatoxins and the psoralens (photosensitizing agents). 2. Coumarin itself (1,2-benzopyrone) has long-established efficacy in slow-onset long-term reduction of lymphoedema in man, as confirmed in recent double-blind trials against elephantiasis and postmastectomy swelling of the arm. The mechanism of action is uncertain, but may involve macrophage-induced proteolysis of oedema protein. However, coumarin has low absolute bioavailability in man (< 5%), due to extensive first-pass hepatic conversion to 7-hydroxycoumarin followed by glucuronidation. It may, therefore, be a prodrug. 3. Scoparone (6,7-dimethoxycoumarin) has been purified from the hypolipidaemic Chinese herb Artemisia scoparia and shown to reduce the proliferative responses of human peripheral mononuclear cells, to relax smooth muscle, to reduce total cholesterol and triglycerides and to retard the characteristic pathomorphological changes in hypercholesterolaemic diabetic rabbits. Various properties of scoparone were suggested to account for these findings, including ability to scavenge reactive oxygen species, inhibition of tyrosine kinases and potentiation of prostaglandin generation. 4. Osthole (7-methoxy-8-[3-methylpent-2-enyl]coumarin) from Angelica pubescens, used also in Chinese medicine, causes hypotension in vivo, and inhibits platelet aggregation and smooth muscle contraction in vitro. It may interfere with calcium influx and with cyclic nucleotide phosphodiesterases. 5. Cloricromene, a synthetic coumarin derivative, also possesses antithrombotic antiplatelet actions, inhibits PMN neutrophil function and causes vasodilatation. Some of these properties of cloricromene have been ascribed to inhibition of arachidonate release from membrane phospholipids. 6. Simple coumarins possessing ortho-dihydroxy functions, such as fraxetin and 4-methyldaphnetin, are potent inhibitors (low micromolar) of lipid peroxidation and scavengers of superoxide anion radicals and of aqueous alkylperoxyl radicals, but may be pro-oxidant (enhancing generation of hydroxyl radicals) in the presence of free iron ions. These coumarins also inhibit the proinflammatory 5-lipoxygenase enzyme at micromolar concentrations. Another related coumarin, 5,7-dihydroxy-4-methylcoumarin, is of special interest as it inhibits lipid peroxidation, and scavenges alkylperoxyl and superoxide radicals. Unlike most other simple coumarins studied, 5,7-dihydroxy-4-methylcoumarin also scavenges hypochlorous acid, and is a potent inhibitor of cyclo-oxygenase, but is not pro-oxidant. 7. 5,7- and 6,7-dihydroxy-4-methylcoumarin both reduced the duration of ventricular fibrillation in postischaemic reperfused isolated perfused rat hearts (in which oxygen-derived free radicals are implicated), showing that these antioxidant coumarins possess beneficial properties in this pathophysiological model. 8. In view of the established low toxicity, relative cheapness, presence in the diet and occurrence in various herbal remedies of coumarins, it appears prudent to evaluate their properties and applications further.