A potential calcium antagonist and its antihypertensive effects

Natural linear coumarin-heterocyclic conjugates: A review of their roles in phytotherapy

Heterocycle conjugates provide a fresh investigative scope to find novel molecules with enhanced phytotherapeutic characteristics. Coumarin-based products are widely used in the synthesis of several compounds with biological and medicinal properties since they are naturally occurring heterocycles with a broad dispersion. The investigation of coumarin-based phytochemicals with annulated heterocyclic rings is a promising approach to discovering novel conjugates with significant phytotherapeutic attributes. Due to the applicable coumarin extraction processes, a range of linear coumarin-heterocyclic conjugates were isolated from different natural resources and exhibited remarkable therapeutic efficacy. This review highlights the phytotherapeutic potential and origins of various natural linear coumarin-heterocyclic conjugates. We searched several databases, including Science Direct, Web of Science, Springer, Google Scholar, and PubMed. After sieving, we ultimately identified and included 118 pertinent studies published between 2000 and the middle of 2023. This will inspire medicinal chemists with extremely insightful ideas for designing and synthesizing therapeutically active lead compounds in the future that are built on the pharmacophores of coumarin-heterocyclic conjugates and have significant therapeutic attributes.

Vasorelaxant and Blood Pressure-Lowering Effects of Cnidium monnieri Fruit Ethanol Extract in Sprague Dawley and Spontaneously Hypertensive Rats

Cnidium monnieri (L.) Cusson, a member of the Apiaceae family, is rich in coumarins, such as imperatorin and osthole. Cnidium monnieri fruit (CM) has a broad range of therapeutic potential that can be used in anti-bacterial, anti-cancer, and sexual dysfunction treatments. However, its efficacy in lowering blood pressure through vasodilation remains unknown. This study aimed to assess the potential therapeutic effect of CM 50% ethanol extract (CME) on hypertension and the mechanism of its vasorelaxant effect. CME (1-30 µg/mL) showed a concentration-dependent vasorelaxation on constricted aortic rings in Sprague Dawley rats induced by phenylephrine via an endothelium-independent mechanism. The vasorelaxant effect of CME was inhibited by blockers of voltage-dependent and Ca2+-activated K+ channels. Additionally, CME inhibited the vascular contraction induced by angiotensin II and CaCl2. The main active compounds of CM, i.e., imperatorin (3-300 µM) and osthole (1-100 µM), showed a concentration-dependent vasorelaxation effect, with half-maximal effective concentration values of 9.14 ± 0.06 and 5.98 ± 0.06 µM, respectively. Orally administered CME significantly reduced the blood pressure of spontaneously hypertensive rats. Our research shows that CME is a promising treatment option for hypertension. However, further studies are required to fully elucidate its therapeutic potential.

Simultaneous separation and determination of six furanocoumarins in Radix Angelicae dahuricae by CZE with dual CDs system

A novel, simple and efficient capillary electrophoresis method was developed to simultaneous determination of six furanocoumarins (psoralen, isopsoralen, imperatorin, isoimperatorin, phellopterin, and cnidilin). The separation buffer consisted of 30 mM boric acid, 12 mM sulfobutylether-β-cyclodextrin and 1.5 mM 2-hydroxypropyl-β-cyclodextrin (pH 7.8); the voltage was 20 kV, the temperature was 25 °C and the detection wavelength was at 246 nm with a diode array detector (DAD). Under the above conditions, the analytes could be separated with high resolution in less than 7 min. This method was used to simultaneously determine the content of psoralen, imperatorin, isoimperatorin and phellopterin in Angelica Dahurica Radix. And good linearities were obtained with correlation coefficients from 0.9992 to 0.9999. The limits of detection (LOD, S/N = 3) and the limits of quantitation (LOQ, S/N = 10) ranged from 0.6 to 3.0 μg/mL and from 2.1 to 9.9 μg/mL, respectively. The recoveries ranged between 98.8% and 101.8%. The results indicated the method can achieve baseline separation and quantitative analysis of furanocoumarins in Chinese herbal medicines and formulations.

Imperatorin alleviates metabolic and vascular alterations in high-fat/high-fructose diet-fed rats by modulating adiponectin receptor 1, eNOS, and p47phox expression

In the present study, the therapeutic effects of imperatorin on metabolic and vascular alterations and possible underlying mechanisms were investigated in high-fat/high-fructose diet (HFFD)-fed rats. Male Sprague-Dawley rats were fed a high-fat diet plus 15% fructose in drinking water for 16 weeks. HFFD-fed rats were treated with imperatorin (15 or 30 mg/kg/day) for the last 4 weeks. In HFFD-fed rats, imperatorin significantly reduced obesity, hypertension, dyslipidemia, and insulin resistance. Imperatorin markedly improved vascular endothelial function and alleviated changes in vascular morphology. Furthermore, imperatorin treatment significantly increased the plasma levels of the nitric oxide metabolite and adiponectin, and upregulated adiponectin receptor 1 and endothelial nitric oxide synthase (eNOS) protein expression in the thoracic aorta. Imperatorin treatment decreased vascular superoxide anion production and downregulated aortic NADPH oxidase subunit p47phox protein expression. These findings indicated that imperatorin alleviates HFFD-induced metabolic and vascular alterations in rats. The possible underlying mechanism may involve the restoration of adiponectin receptor 1 and eNOS expression and suppression of p47phox expression.

Effects of imperatorin on apoptosis and synaptic plasticity in vascular dementia rats

In view of the complicated pathophysiological process of vascular dementia (VD), drugs for the clinical treatment of VD mainly target related risk factors, while drugs with excellent efficacy in cognitive function are still relatively lacking. Imperatorin (IMP), an active constituent extracted from angelica dahuricae and notopterygium Notopterygii, which has anti-inflammatory, vasodilator, anticoagulant, block calcium channel, anticonvulsant, and anti oxygen free radical injury properties. Therefore,the present study examined its effects on VD rats and the underlying molecular mechanisms, in order to provide promising therapeutic methods. VD was established by modified ligation of perpetual two-vessel occlusion (2VO). After 2VO surgery, IMP (2.5, 5, and 10 mg/kg) was administered by intraperitoneal injection for 12 consecutive weeks to evaluate therapeutic effects. Cognitive function was verified by the Morris water maze. The neuronal morphological changes were examined via Hematoxylin-Eosin staining. Real-Time PCR and Western blot were used for detecting pro- and antiapoptotic biomarkers, and the hippocampus synaptic damage was examined by Transmission electron microscope. We revealed that 2VO-induced cognitive impairment, hippocampus CA1 neuron damage, apoptosis and synaptic damage. IMP-treatment significantly improved 2VO-induced cognitive deficits and hippocampus neuron damage. Molecular analysis revealed that IMP inhibited apoptosis through the down regulation of Bax, Caspase-3 and upregulation of Bcl-2. Meanwhile, IMP-treatment markedly improved synaptic ultrastructure morphology, increased the SAZ length, PSD thickness and up-regulated PSD-95 expression. Collectively, our findings demonstrated that IMP was effective in the treatment of 2VO-induced VD via inhibiting apoptosis of hippocampus neurons and reducing the synaptic plasticity destroy.

Gut Metabolism of Furanocoumarins: Proposed Function of Co O-Methyltransferase

Gut metabolism of natural products is of great interest due to the altered biological activity of the metabolites. To study the gut metabolism of the dietary furanocoumarins, the biotransformation of Angelica dahurica was studied with human gut microbiota. The major components of Avenula dahurica, including xanthotoxin (1), bergapten (2), imperatorin (3), isoimperatorin (4), oxypeucedanin (5), and byakangelicol (6), were all metabolized by the human fecal sample, and each furanocoumarin was also biotransformed by Blautia sp. MRG-PMF1 responsible for intestinal O-demethylation. Oxypeucedanin (5) and byakangelicol (6) were converted to oxypeucedanin hydrate (9) and desmethylbyakangelicin (12), respectively. The gut microbial conversion of xanthotoxin (1) and bergapten (2) with the MRG-PMF1 strain resulted in the production of xanthotoxol (7) and bergaptol (8), respectively, due to the methyl aryl ether cleavage by O-methyltransferase. Unexpectedly, the biotransformation of prenylated furanocoumarins, imperatorin (3), and isoimperatorin (4) resulted in the corresponding deprenylated furanocoumarins of xanthotoxol (7) and bergaptol (8), respectively. The cleavage of the prenyl aryl ether group by gut microbiota was unprecedented metabolism. Our data presented the first deprenylation of prenylated natural products, presumably by the anaerobic prenyl aryl ether cleavage reaction catalyzed by Co-corrinoid enzyme.

Imperatorin Relieved Ulcerative Colitis by Regulating the Nrf-2/ARE/HO-1 Pathway in Rats

Ulcerative colitis is a common intestinal inflammatory disease. Imperatorin (IMP) has been reported to alleviate mast cell-mediated allergic responses by suppressing the expression of Nrf-2, ARE, and HO-1. However, whether IMP can relieve ulcerative colitis by regulating Nrf-2/ARE/HO-1 pathway is unclear. Thus, this study aims to investigate the effect of IMP on ulcerative colitis in rats and elucidate the potential mechanism. In our study, rats were treated with 2,4,6-trinitro-benzenesulfonic acid (TNBS) to induce the animal model of ulcerative colitis. Next, these rats were treated with diverse doses of IMP (15 mg/kg, 30 mg/kg, and 60 mg/kg) and sacrificed at different time points (3 days, 7 days, and 14 days). The levels of inflammatory factors (TNF-α and IL-6) in colon tissues were detected with ELISA kits. H&E staining was performed to observe the pathologic changes of the colon tissues. The expression of Nrf-2, ARE, and HO-1 in colon tissues was determined with the immunofluorescence and Western blotting. The results showed that application of IMP alleviated the symptoms of ulcerative colitis and inhibited the secretion of TNF-α and IL-6. Besides, treatment of IMP promoted the expression of Nrf-2, ARE, and HO-1 in the early stage of this disease (the third day), but suppressed the expression of Nrf-2, ARE, and HO-1 in the advanced stage of the ulcerative colitis (the fourteenth day). Collectively, IMP relieved the symptoms of ulcerative colitis by regulating the Nrf-2/ARE/HO-1 pathway, which might provide a new therapeutic drug to support the clinical treatment of ulcerative colitis.

Antiviral activity of furanocoumarins isolated from Angelica dahurica against influenza a viruses H1N1 and H9N2

ETHNOPHARMACOLOGICAL RELEVANCE

Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav. (Umbelliferae family) is an herbaceous, perennial plant native to northern and eastern Asia. The root of A. dahurica has traditionally been used under the name "Bai Zhi" as a medicinal plant for colds, dizziness, ulcers, and rheumatism. Moreover, it is also an important ingredient of various prescriptions, such as Gumiganghwal-Tang, for the common cold and influenza.

AIM OF THE STUDY

Even though various biological activities of the root of A. dahurica have been reported along with its chemical components, the detailed mechanism of how it exerts anti-influenza activity at the compound level has not been studied. Therefore, we investigated the anti-influenza properties of furanocoumarins purified by bioactivity-guided isolation.

MATERIALS AND METHODS

Bioactivity-guided isolation from a 70% EtOH extract of the root of A. dahurica was performed to produce four active furanocoumarins. The inhibition of cytopathic effects (CPEs) was evaluated to ascertain the antiviral activity of these compounds against influenza A (H1N1 and H9N2) viruses. The most potent compound was subjected to detailed mechanistic studies such as the inhibition of viral protein synthesis, CPE inhibition in different phases of the viral replication cycle, neuraminidase (NA) inhibition, antiapoptotic activity using flow cytometry, and immunofluorescence.

RESULTS

The bioactivity-guided isolation produced four active furanocoumarins, isoimperatorin (1), oxypeucedanin (2), oxypeucedanin hydrate (3) and imperatorin (4) from the n-BuOH fraction. Among them, compound 2 (followed by compounds 1, 4 and 3) showed a significant CPE inhibition effect, which was stronger than that of the positive control ribavirin, against both H1N1 and H9N2 with an EC₅₀ (μM) of 5.98 ± 0.71 and 4.52 ± 0.39, respectively. Compound 2 inhibited the synthesis of NA and nucleoprotein (NP) in a dose-dependent manner. In the time course assays, the cytopathic effects of influenza A-infected MDCK cells were reduced by 80-90% when treated with compound 2 for 1 and 2 h after infection and declined drastically 3 h after infection. The level of viral NA and NP production was markedly reduced to less than 20% for both proteins in compound 2 (20 μM)-treated cells compared to untreated cells at 2 h after infection. In the molecular docking analysis, compound 2 showed a stronger binding affinity for the C-terminus of polymerase acidic protein (PAC; -36.28 kcal/mol) than the other two polymerase subunits. Compound 2 also exerted an antiapoptotic effect on virus infected cells and significantly inhibited the mRNA expression of caspase-3 and Bax.

CONCLUSION

Our results suggest that compound 2 might exert anti-influenza A activity via the inhibition of the early phase of the viral replication cycle, not direct neutralization of surface proteins, such as hemagglutinin and NA, and abnormal apoptosis induced by virus infection. Taken together, these findings suggest that furanocoumarins predominant in A. dahurica play a pivotal role in its antiviral activity. These findings can also explain the reasons for the ethnopharmacological uses of this plant as an important ingredient in many antiviral prescriptions in traditional Chinese medicine (TCM).

Imperatorin: A review of its pharmacology, toxicity and pharmacokinetics

As a naturally occurring furanocoumarin, the medicinal value of imperatorin has been studied more and more. We hope to provide useful information for the further development of imperatorin by analyzing the literature of imperatorin in recent years. By collating the literature on the pharmacology of imperatorin, we found that the pharmacological activity of imperatorin is wide and imperatorin can be used for anti-cancer, neuroprotection, anti-inflammatory, anti-hypertension and antibacterial. In addition, we found that some researchers confirmed the toxicity of imperatorin. Pharmacokinetic studies demonstrated that oxidation metabolism is the main metabolic pathways of imperatorin. At present, the shortcomings of research on imperatorin mainly include: most pharmacological studies are concentrated in vitro, lacking enough in vivo experimental data; more and more studies showed that imperatorin has synergistic effect with other drugs in anticancer and other aspects, but lacking the detailed explanation of the mechanism of the synergistic effect; imperatorin has side effect, but it lacks enough experimental conclusions. Based on the above defects, we believe that more in vivo experiments of imperatorin should be carried out in the future; future research need to explore synergistic mechanisms of imperatorin with other drugs, especially in anticancer; the dose affects both the pharmacological activity and the side effect of imperatorin. The relationship between the dose and the two aspects need to be further studied in order to reduce the side effect. In addition, through structural modification of imperatorin, it is possible to improve the treatment effect and reduce side effect.

Phytochemistry, Ethnopharmacology, Pharmacokinetics and Toxicology of Cnidium monnieri (L.) Cusson

Cnidium monnieri (L.) Cusson (CMC) is a traditional Chinese herbal medicine that has been widely grown and used in Asia. It is also known as "She chuang zi" in China (Chinese: ), "Jashoshi" in Japan, "Sasangia" in Korea, and "Xa sang tu" in Vietnam. This study aimed to provide an up-to-date review of its phytochemistry, ethnopharmacology, pharmacokinetics, and toxicology. All available information on CMC was collected from the Encyclopedia of Traditional Chinese Medicines, PubMed, EMBASE, ScienceDirect, Scopus, Web of Science, and China Network Knowledge Infrastructure. The updated chemical structures of the compounds are those ones without chemical ID numbers or references from the previous review. A total of 429 chemical constituents have been elucidated and 56 chemical structures have been firstly identified in CMC with traceable evidence. They can be categorized as coumarins, volatile constituents, liposoluble compounds, chromones, monoterpenoid glucosides, terpenoids, glycosides, glucides, and other compounds. CMC has demonstrated impressive potential for the management of various diseases in extensive preclinical research. Since most of the studies are overly concentrated on osthole, more research is needed to investigate other chemical constituents.

Anti-inflammatory Property of Imperatorin on Alveolar Macrophages and Inflammatory Lung Injury

Imperatorin is one of the furanocoumarin derivatives and exists in many medicinal herbs with anticancer, antiviral, antibacterial, and antihypertensive activities. In this study, we examined the anti-inflammatory effects of imperatorin on inflammation-associated lung diseases. Imperatorin reduced iNOS and COX-2 expression and also IL-6 and TNFα production enhanced by zymosan. Imperatorin also inhibited the signaling pathways of JAK/STAT and NF-κB. Moreover, in vivo study also revealed that zymosan-induced immune cell infiltration, pulmonary fibrosis, and edema were relieved by imperatorin in mice. We found that imperatorin exerts anti-inflammatory effects that are associated with amelioration of lung inflammation, edema, and rapid fibrosis. Studies on alveolar macrophages also reveal that imperatorin reduced the production of pro-inflammatory mediators and cytokines and inhibited pro-inflammatory JAK1/STAT3 and NF-κB signaling pathways. These results indicate that imperatorin may be a potential anti-inflammatory agent for inflammatory-associated lung diseases.

Imperatorin Suppresses Anaphylactic Reaction and IgE-Mediated Allergic Responses by Inhibiting Multiple Steps of FceRI Signaling in Mast Cells: IMP Alleviates Allergic Responses in PCA

This study is to investigate the effects of imperatorin (IMP) on allergic responses mediated by mast cells, both in vitro and in vivo. Passive cutaneous anaphylaxis (PCA) model was established. Histological detection was performed to assess the ear histology. ELISA and Western blot analysis were used to detect the levels of corresponding cytokines and signalling pathway proteins. IMP decreased the leakage of Evans blue and the ear thickness in the PCA models, in a dose-dependent manner, and alleviated the degranulation of mast cells. Moreover, IMP reduced the expression of TNF-α, IL-4, IL-1β, IL-8, and IL-13. Furthermore, IMP inhibited the phosphorylation levels of Syk, Lyn, PLC-γ1, and Gab2, as well as the downstream MAPK, PI3K/AKT, and NF-κB signaling pathways. In addition, IMP inhibited the mast cell-mediated allergic responses through the Nrf2/HO-1 pathway. IMP attenuates the allergic responses through inhibiting the degranulation and decreasing the expression levels of proinflammatory cytokines in the mast cells, involving the PI3K/Akt, MAPK, NF-κB, and Nrf2/HO-1 pathways.

Biomolecular Targets of Oxyprenylated Phenylpropanoids and Polyketides

Oxyprenylated secondary metabolites (e.g. phenylpropanoids and polyketides) represent a rare class of natural compounds. Over the past two decades, this group of phytochemicals has become a topic of intense research activity by several teams worldwide due to their in vitro and in vivo pharmacological activities, and to their great therapeutic and nutraceutical potential for the chemoprevention of acute and chronic diseases affecting humans. Such investigations have provided evidence that oxyprenylated secondary metabolites are able to interact with several biological targets at different levels accounting for their observed anticarcinogenic, anti-inflammatory, neuroprotective, immunomodulatory, antihypertensive, and metabolic effects. The aim of the present contribution is to provide a detailed survey of the so far reported data on the capacities of selected oxyprenylated phenylpropanoids and polyketides to trigger receptors, enzymes, and other types of cellular factors for which they exhibit a high degree of affinity and therefore evoke specific responses. With respect to the rather small amounts of these compounds available from natural sources, their chemical synthesis is also highlighted.

Increased skin permeation efficiency of imperatorin via charged ultradeformable lipid vesicles for transdermal delivery

Aim

The aim of this work was to develop a novel vesicular carrier, ultradeformable liposomes (UDLs), to expand the applications of the Chinese herbal medicine, imperatorin (IMP), and increase its transdermal delivery.

Methods

In this study, we prepared IMP-loaded UDLs using the thin-film hydration method and evaluated their encapsulation efficiency, vesicle deformability, skin permeation, and the amounts accumulated in different depths of the skin in vitro. The influence of different charged surfactants on the properties of the UDLs was also investigated.

Results

The results showed that the UDLs containing cationic surfactants had high entrapment efficiency (60.32%±2.82%), an acceptable particle size (82.4±0.65 nm), high elasticity, and prolonged drug release. The penetration rate of IMP in cationic-UDLs was 3.45-fold greater than that of IMP suspension, which was the highest value among the vesicular carriers. UDLs modified with cationic surfactant also showed higher fluorescence intensity in deeper regions of the epidermis.

Conclusion

The results of our study suggest that cationic surfactant-modified UDLs could increase the transdermal flux, prolong the release of the drug, and serve as an effective dermal delivery system for IMP.

Imperatorin suppresses proliferation and angiogenesis of human colon cancer cell by targeting HIF-1α via the mTOR/p70S6K/4E-BP1 and MAPK pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Angelica dahurica is a commonly used traditional Chinese medicine to treat migraine headache, toothache and cancer. Imperatorin is an active natural furocoumarin component originating from Angelica dahurica and has been shown to exhibit multiple bioeffector functions, including anti-cancer activity. However, the mechanism by which imperatorin inhibits tumor growth is not fully understood.

AIM OF THE STUDY

The aim of this study was to investigate the effectiveness of imperatorin as a treatment of cancer and to identify the underlying mechanisms of its anticancer activity.

MATERIALS AND METHODS

HCT116, HeLa, and Hep3B cells were used in this study. Major assays were promoter-reporter gene assay, MTT, western blot analysis, immunofluorescence assay, reverse transcription-PCR (RT-PCR), flow cytometric analysis, clonogenic assay, EdU labeling and immunofluorescence, xenografted assay, and VEGF ELISA.

RESULTS

We here demonstrated the effect of imperatorin on hypoxia-inducible factor-1 (HIF-1) activation. Imperatorin showed a potent inhibitory activity against HIF-1 activation induced by hypoxia in various human cancer cell lines. This compound markedly decreased the hypoxia-induced accumulation of HIF-1α protein dose-dependently, whereas it did not affect the expressions of HIF-1β and topoisomerase-I (Topo-I). Further analysis revealed that imperatorin inhibited HIF-1α protein synthesis, without affecting the expression level of HIF-1α mRNA or degradation of HIF-1α protein. Moreover, the phosphorylation levels of mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70S6K), eIF4E binding protein-1 (4E-BP1), eukaryotic initiation factor 4E (eIF4E), extracellular signal-regulated kinase-1/2 (ERK1/2), SAPK/JNK and p38 were significantly suppressed by imperatorin. Furthermore, imperatorin prevented hypoxia-induced expression of HIF-1 target genes and flow cytometric analysis indicated that imperatorin induced G1 phase arrest in human colon cancer cell (HCT116). We found that imperatorin administration inhibits tumor growth and blocks tumor angiogenesis in a xenograft tumor model.

CONCLUSIONS

These results show that imperatorin inhibited HIF-1α protein synthesis by downregulating the mTOR/p70S6K/4E-BP1 and MAPK pathways. These conclusions suggest that imperatorin is an effective inhibitor of HIF-1 and provide new perspectives into the mechanism of its anticancer activity.

Four Main Active Ingredients Derived from a Traditional Chinese Medicine Guanxin Shutong Capsule Cause Cardioprotection during Myocardial Ischemia Injury Calcium Overload Suppression

Guanxin Shutong capsule is a traditional Chinese medicine for the treatment of myocardial ischemia (MI). Previous studies have shown that the formula has four main active ingredients (FMAI), protocatechuic acid, cryptotanshinone, borneol, and eugenol. However, the mechanisms of action of these FMAI against MI injury are still not well known. The aim of the present study was to evaluate the protective effects of the FMAI on MI in vitro and in vivo. In vitro, rat neonatal cardiomyocytes were isolated, the cell viability and apoptosis rate were, respectively, measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and fluorescence activating cell sorter, and the intracellular calcium concentration ([Ca²⁺ ]_i ) and CaM and CaMKII δ mRNA as well as protein levels were determined. Meanwhile, their downstream targets of RyR2 and PLB were also measured by western blot. In vivo, a rat model of coronary artery ligation was used to evaluate the cardioprotective effects. Infarct sizes of heart tissues and levels of serum biochemical indicators, including creatine kinase, lactate dehydrogenase, superoxide dismutase, and glutamate oxaloacetic transaminase, were measured. The in vitro results showed that the FMAI inhibited cell apoptosis, reduced [Ca²⁺ ]_i , decreased the expression of CaM and CaMKII δ, and increased the expression of RyR2 and PLB. In vivo, the FMAI diminished infract size, reduced creatine kinase, lactate dehydrogenase, and aspartate aminotransferase levels, and enhanced superoxide dismutase activity. In conclusion, our data suggest that the FMAI suppressed calcium overload and exerted its protective effect via its antioxidant, antiinflammatory, and anti-apoptosis activities. Copyright © 2017 John Wiley & Sons, Ltd.

Current natural products with antihypertensive activity

Natural products have been an important source of new drugs, which also played a dominant role in the discovery and research of new drugs for the treatment of hypertension. This review article reviews the recent progress in the research and development of natural lead compounds with antihypertensive activity, including alkaloids, diterpenes, coumarins, flavonoids, and peptides. We summarized their structures, sources, as well as the antihypertensive mechanisms. These information provides instructive reference for the following structural modifications and optimization.

Preventive effects of imperatorin on perfluorohexanesulfonate-induced neuronal apoptosis via inhibition of intracellular calcium-mediated ERK pathway

Early life neuronal exposure to environmental toxicants has been suggested to be an important etiology of neurodegenerative disease development. Perfluorohexanesulfonate (PFHxS), one of the major perfluoroalkyl compounds, is widely distributed environmental contaminants. We have reported that PFHxS induces neuronal apoptosis via ERK-mediated pathway. Imperatorin is a furanocoumarin found in various edible plants and has a wide range of pharmacological effects including neuroprotection. In this study, the effects of imperatorin on PFHxS-induced neuronal apoptosis and the underlying mechanisms are examined using cerebellar granule cells (CGC). CGC were isolated from seven-day old rats and were grown in culture for seven days. Caspase-3 activity and TUNEL staining were used to determine neuronal apoptosis. PFHxS-induced apoptosis of CGC was significantly reduced by imperatorin and PD98059, an ERK pathway inhibitor. PFHxS induced a persistent increase in intracellular calcium, which was significantly blocked by imperatorin, NMDA receptor antagonist, MK801 and the L-type voltage-dependent calcium channel blockers, diltiazem and nifedipine. The activation of caspase-3 by PFHxS was also inhibited by MK801, diltiazem and nifedipine. PFHxS-increased ERK activation was inhibited by imperatorin, MK801, diltiazem and nifedipine. Taken together, imperatorin protects CGC against PFHxS-induced apoptosis via inhibition of NMDA receptor/intracellular calcium-mediated ERK pathway.

Imperatorin-pharmacological meaning and analytical clues: profound investigation

Imperatorin, a furanocoumarin derivative, has many documented pharmacological properties which make it a candidate for possible drug development. In this review, the activity on the central nervous system, the anticancer and antiviral properties and the influence on the cardiovascular system are described. The aim of this review is also to present an overview of the techniques used for the analysis, isolation, and separation of imperatorin from plant material from the practical perspective.

Cnidium monnieri: A Review of Traditional Uses, Phytochemical and Ethnopharmacological Properties

Cnidium monnieri (L.) Cuss., an annual plant of the Umbelliferae species is one of the most widely used traditional herbal medicines and its fruits have been used to treat a variety of diseases in China, Vietnam, and Japan. The aim of this review is to provide an up-to-date and comprehensive analysis of the botany, traditional uses, phytochemistry, pharmacology, toxicity and contraindication of Cnidium monnieri (L.) Cuss. and to provide future directions of research on this plant. To date, 350 compounds have been isolated and identified from Cnidium monnieri (L.) Cuss., including the main active constituent, coumarins. In vitro and in vivo studies suggest that osthole and other coumarin compounds possess wide range of pharmacological properties for the treatment of female genitals, male impotence, frigidity, skin-related diseases, and exhibit strong antipruritic, anti-allergic, antidermatophytic, antibacterial, antifungal, anti-osteoporotic effects. Although coumarins have been identified as the main active constituents responsible for the observed pharmacological effects, the molecular mechanisms of their actions are still unknown. Therefore, further studies are still required to reveal the structure-activity relationship of these active constituents. In addition, toxicological and clinical studies are also required to provide further data for pharmaceutical use.

Antihypertensive and vascular remodelling effects of the imperatorin derivative OW1 in renovascular hypertension rats

OW1 is a novel imperatorin derivative that exhibits vasodilator activity. In the present study, the antihypertensive effect of and inhibition of vascular remodelling by OW1 were investigated in two-kidney, one-clip (2K1C) renovascular hypertensive rats. Rats were subjected to the 2K1C procedure and treated with OW1 (40 or 80 mg/kg per day) for 8 weeks. Blood pressure was measured in conscious rats. Microalbumin (mALB) and total protein (U-TP) concentrations were determined in the urine, as were plasma concentrations of angiotensin (Ang) II, calcitonin gene-related peptide (CGRP) and angiotensin-converting enzyme 1 (ACE). The unclipped kidney was stained with haematoxylin and eosin and Masson trichrome, whereas aortic sections were stained with Masson trichrome. In addition, OW1-induced vasodilatation was evaluated in vitro in rat mesenteric and renal arteries. Immunohistochemical analysis was used to quantify collagen I and III expression. OW1 relaxed rat mesenteric and renal arterial rings in vitro. Treatment of 2K1C hypertensive rats with OW1 (40 and 80 mg/kg per day) for 8 weeks significantly decreased blood pressure. In addition, OW1 reduced plasma AngII and ACE concentrations and increased plasma CGRP concentrations. At 80 mg/kg per day, OW1 decreased blood urea nitrogen, mALB and U-TP levels. Histological analysis revealed that OW1 reduced renal arteriolar thickness and relieved the structural hypertrophic arteries. Moreover, OW1 had an inhibitory effect on vascular remodelling and renal lesions in hypertensive rats. In conclusion, the results suggest that OW1 could potentially be a novel candidate for hypertension intervention.

Vasodilation and radical-scavenging activity of imperatorin and selected coumarinic and flavonoid compounds from genus Casimiroa

Hypertension is a very widespread condition which is not strictly considered as an illness but if not countered, progressively causes damage to all tissues and loss in their functionality. For this reason the find of new antihypertensive agents is prominent and medicinal plants and their derivatives are valuable for the purpose. The genus Casimiroa (Rutaceae) includes plants from Central America and Mexico; among these, Casimiroa edulis Llave et Lex. and Casimiroa pubescens Ramirez are the most relevant species, even for their medicinal uses. The decoction of leaves and seeds is traditionally taken as a tea mainly to lower blood pressure. The object of this research was the study of vascular activity of coumarinic and flavonoid compounds isolated from seeds of Casimiroa spp. in comparison with Casimiroa edulis and Casimiroa pubescens extracts. The phenolic compounds isolated from Casimiroa were herniarin (Her), imperatorin (Imp), 8-geranyloxypsoralen (GOP) and 5,6,2',3',4'-pentamethoxyflavone (PMF). All these compounds induced vasorelaxation on rat arterial tissues although with different effectiveness. To study the cellular mechanisms of the vasorelaxation exhibited by imperatorin, we used selective inhibitors of different receptors and enzymes, such as atropine, pyrilamine, nifedipine, L-NAME and DETC. In a further step of this research, we evaluated the radical-scavenging activity of Casimiroa extracts and isolated compounds by means of DPPH assay. In general, we observed that the scavenging activities increased in a concentration-dependent manner for all substances. The phenolic compounds highlight a synergism of vasodilation and antioxidant activity which may be very useful in the management of cardiovascular diseases. Among the evaluated compounds, imperatorin shows a significant vasorelaxant activity even higher than acetylcholine and similar to nitrite, and also useful antiradical capabilities. All these properties suggest its possible role against hypertension and vasculopathies, even if in vivo studies are needed to determine the actual applications.

Extracts and Fractions from Edible Roots of Sechium edule (Jacq.) Sw. with Antihypertensive Activity

Sechium edule is traditionally used in Mexico as a therapeutic resource against renal diseases and to control high blood pressure. The purpose of this work is to evaluate the antihypertensive effect of the hydroalcoholic extract obtained from the roots of this plant, including its fractions and subfractions, on different hypertension models induced with angiotensin II (AG II). The hydroalcoholic extract was tested on an in vitro study of isolated aorta rings denuded of endothelial cells, using AG II as the agonist; this assay proved the vasorelaxant effect of this extract. Vagotomized rats were administered different doses of AG II as well as the Hydroalcoholic extract, which reduced blood pressure in 30 mmHg approximately; subsequently this extract was separated into two fractions (acetone and methanol) which were evaluated in the acute hypertension mouse model induced with AG II, where the acetone fraction was identified as the most effective one and was subsequently subfractioned using an open chromatographic column packed with silica gel. The subfractions were also evaluated in the acute hypertension model. Finally, the extract, fraction, and active subfraction were analyzed by MS-PDA-HPLC, identifying cinnamic derivative compounds like cinnamic acid methyl ester.

Effects of imperatorin, the active component from Radix Angelicae (Baizhi), on the blood pressure and oxidative stress in 2K,1C hypertensive rats

The 2-kidney, 1-clip (2K,1C) model of hypertension was used to investigate the potential antihypertensive and antioxidant effect of imperatorin extracted from the root of radix angelicae. After 10 weeks treatment of imperatorin, mean blood pressure (MBP) of 2K,1C hypertensive rats was obtained, and superoxide dismutase (SOD), nitric oxide (NO) and nitric oxide synthase (NOS) were measured. Malondialdehyde (MDA) and glutathione (GSH) levels, catalase (CATA), xanthine oxidase (XOD), angiotensinII (Ang II) and endothelin (ET) levels of kidney were evaluated with commercial kits. Nicotinamide adenine dinucleotidephosphate (NADPH) oxidase subunits of the renal cortial tissues were determined by RT-PCR and Western blot. 8-Iso-prostaglandin F2α (8-iso-PGF2α) of 24h urinary excretion was also measured by ELISA. MBP was significantly reduced by treatment with IMP (6.25, 12.5 and 25 mg/kg/day, i.g.) in 2K,1C hypertensive rats. Meanwhile, we found that renal CATA and XOD activities, GSH levels, plasma NO and NOS contents were significantly increased in IMP-treated groups. Plasma ET, renal Ang II levels, MDA and the 24h urinary excretion of 8-iso-PGF2α in the IMP treated group were lower than control SD group. After that, we found the mRNA expressions and protein levels of NADPH oxidase subunits in the clipped kidney were markedly reduced after IMP treated in 2K,1C hypertensive rats. IMP showed antihypertensive and antioxidant effects in the renal injury of renovascular hypertensive rats, suggesting that IMP could be of therapeutic use in preventing renal injury related hypertension.

Design, synthesis, and vasorelaxation activity of novel imperatorin derivatives

In this study, a series of novel imperatorin derivatives 7a-7e were designed and synthesized. Their vasorelaxation activities were evaluated by the pharmacological experiments in vitro. Most of the tested compounds exhibited better water solubility and vasorelaxation activity in different degrees, especially 7b and 7c with EC50 values of 2.29 and 2.63 μM, respectively on mesenteric artery, 7d and 7e with EC50 values of 1.04 and 2.65 μM, respectively on brain artery. The results indicated that these novel compounds have a potential interest for the development of novel and potent vasorelaxant agents for different kinds of arteries.