Effects of praeruptorin C and E isolated from 'Qian-Hu' on swine coronary artery and guinea-pig atria

The Vasodilatory Effects of Anti-Inflammatory Herb Medications: A Comparison Study of Four Botanical Extracts

Inflammation plays a pivotal role in the development and progression of cardiovascular diseases, in which, the endothelium dysfunction has been a key element. The current study was designed to explore the vasodilatory effect of anti-inflammatory herbs which have been traditionally used in different clinical applications. The total saponins from Actinidia arguta radix (SAA), total flavonoids from Glycyrrhizae radix et rhizoma (FGR), total coumarins from Peucedani radix (CPR), and total flavonoids from Spatholobi caulis (FSC) were extracted. The isometric measurement of vasoactivity was used to observe the effects of herbal elements on the isolated aortic rings with or without endothelium. To understand endothelium-independent vasodilation, the effects of herb elements on agonists-induced vasocontractility and on the contraction of endothelium-free aortic rings exposed to a Ca²⁺-free medium were examined. Furthermore, the role of nitric oxide signaling in endothelium-dependent vasodilation was also evaluated. In summary, FGR and FSC exhibit potent anti-inflammatory effects compared to CPR and SAA. FGR exerts the strongest vasodilatory effect, while CPR shows the least. The relaxation induced by SAA and FSC required intact endothelia. The mechanism of this vasodilation might involve eNOS. CPR-mediated vasorelaxation appears to involve interference with intracellular calcium homeostasis, blocking Ca²⁺ influx or releasing intracellular Ca²⁺.

Traditional uses, phytochemistry and pharmacological properties of the genus Peucedanum: a review

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Peucedanum (Apiaceae) comprising more than 120 species is widely distributed in Europe, Asia and Africa. The ethnopharmacologial history of this genus indicated that some extracts of aerial and underground parts of several Peucedanum species have been used in folk medicine for treatment of various conditions, such as cough, cramps, pain, rheumatism, asthma and angina. This review focuses on ethnopharmacological uses of Peucedanum species, as well as the phytochemical, pharmacological and toxicological studies on this genus. Through this review, I intend to highlight the known and potential effects of the Peucedanum species or their isolated compounds and show which traditional medicine uses have been supported by pharmacological investigations.

METHODS

Information on the Peucedanum species was collected from scientific journals, books, thesis and reports via a library and electronic search (using Google Scholar, Pubmed, Scopus, Web of Science and ScienceDirect). This review covers the available literature from 1970 to the end of September 2013.

RESULTS

Although, there are about 120 species in this genus, so far many species have received no or little attention and most of pharmacological studies were performed on just about 20 species. Many phytochemical investigations on this genus confirmed that Peucedanum species are rich in essential oils and coumarins. The present review article shows that Peucedanum species have a wide spectrum of pharmacological activities and the most reported activities of Peucedanum plants come back to the presence of coumarins, flavonoids, phenolics and essential oils.

CONCLUSIONS

The present review confirms that some Peucedanum species have emerged as a good source of the traditional medicine for treatment of inflammation, microbial infections, cardiopulmonary diseases and provides new insights for further investigations on isolated compounds, especially on praeruptorins, to find novel therapeutics and aid drug discovery. However, for using Peucedanum species to prevent and treat various diseases, additional pharmacological studies to find the mechanism of action, safety and efficacy of them before starting clinical trials are required.

Biological activities and pharmacokinetics of praeruptorins from Peucedanum species: a systematic review

Praeruptorins belonging to the angular-type pyranocoumarins are bioactive constituents that have been isolated from some Peucedanum species such as P. praeruptorum, which is used in traditional Chinese medicine for treatment of cold, cough, upper respiratory infections, and so forth. Many reports have demonstrated that the beneficial pharmacological effects of P. praeruptorum root on cardiovascular, pulmonary, immune, and nervous system diseases were attributed to the presence of praeruptorins. The aim of this review is to explain the recent efforts of scientists in pharmacological screening of natural and synthetic praeruptorin derivatives, studying the mechanisms of some praeruptorins action, pharmacokinetics, toxicity, and relevant structure-activity relationships. Based on reported data about the pharmacological properties of praeruptorins and semisynthetic derivatives of them, it is hopeful that in the near future more studies focus on the discovery of the new application and therapeutic uses of these bioactive compounds and understanding the specific mechanisms of them. The present discusses the reports on molecular and biological activities of praeruptorins of the genus Peucedanum, from 1976 onwards.

PXR-Mediated Upregulation of CYP3A Expression by Herb Compound Praeruptorin C from Peucedanum praeruptorum Dunn

We recently reported that Praeruptorin C effectively transactivated the mRNA, protein expression, and catalytic activity of CYP3A4 via the CAR-mediated pathway, but whether and how PC could affect the expression and catalytic activity of CYP3A4 via PXR pathway remains unknown. Therefore, in this study, the effect of PC on the CYP3A gene expression was investigated in mice primary hepatocytes after knockdown of PXR by transient transfection of PXR siRNA, and the gene expression, protein expression, and catalytic activity of CYP3A4 in the LS174T cells with PXR overexpression were determined by real-time PCR, western blot analysis, and LC-MS/MS-based CYP3A4 substrate assay, respectively. We found that the level of CYP3a11 gene expression in mouse primary hepatocytes was significantly increased by praeruptorin C, but such an induction was suppressed after knockdown of pregnane X receptor by its siRNA. In PXR-overexpressed LS174T cells, PC significantly enhanced CYP3A4 mRNA, protein expression, and functional activity through PXR-mediated pathway; conversely, no such increase was found in the untransfected cells. These findings suggest that PC can significantly upregulate CYP3A level via the PXR-mediated pathway, and this should be taken into consideration to predict any potential herb-drug interactions between PC, Qianhu, and the other coadministered drugs.

Stereoselective metabolism of (±)-praeruptorin A, a calcium channel blocker from Peucedani Radix, in pooled liver microsomes of rats and humans

(±)-Praeruptorin A (PA) is the major component of Peucedani Radix. The present study investigated stereoselectivity in PA metabolism in liver microsomes of rats (RLMs) and humans (HLMs), for the first time. PA was enantioseparated by semi-preparative chiral HPLC. Metabolic profiles of the dextrorotatory (dPA) and the levorotatory (lPA) forms in HLMs and RLMs were determined using LC-MS/MS. (-)-cis-Khellactone (D1) prepared from basic hydrolysis of dPA, and (3'R, 4'R)-4'-angeloyl-khellactone (L8) and (3'R, 4'R)-3'-angeloyl-khellactone (L9) isolated from a scale-up incubation of lPA with rat plasma were unambiguously identified by LC-MS/MS and NMR analysis. Other metabolites were tentatively identified using LC-MS/MS. In the absence of NADPH-regenerating system, dPA remained intact, however, lPA yielded L8 and L9 via a carboxylesterase(s)-mediated process. In the presence of NADPH-regenerating system, lPA produced 9 (L1-9) metabolites in both species, while dPA generated 12 (D1-12) and 6 (D1-3, 6, 9 and 10) metabolites in RLMs and HLMs, respectively. Hydrolysis, oxidation and acyl migration were demonstrated to be the predominant pathways for both enantiomers. Both enantiomers were eliminated faster in RLMs than in HLMs, while lPA showed greater species difference. PA enantiomers exhibited stereoselective metabolism in RLMs and HLMs, implying chiral discrimination in their actions.

(+/-)-Praeruptorin A enantiomers exert distinct relaxant effects on isolated rat aorta rings dependent on endothelium and nitric oxide synthesis

Praeruptorin A is a coumarin compound naturally occurring in the roots of Peucedanum praeruptorum Dunn., a commonly used traditional Chinese medicine for the treatment of certain respiratory diseases and hypertension. Although previous studies indicated the relaxant effects of (+/-)-praeruptorin A on tracheal and arterial preparations, little is known about the functional characteristics of the enantiomers. In the present study, the two enantiomers were successfully isolated and identified by using a preparative Daicel Chiralpak AD-H column, and their relaxant effects on aorta rings were observed and compared. (+)-Praeruptorin A showed more potent relaxation than (-)-praeruptorin A against KCl- and phenylephrine-induced contraction of rat isolated aortic rings with intact endothelium. Removal of the endothelium remarkably reduced the relaxant effect of (+)-praeruptorin A but not that of (-)-praeruptorin A. Pretreatment of aortic rings with N(omega)-nitro-L-arginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) or methylene blue (MB, a soluble guanylyl cyclase inhibitor) resulted in similar changes of the relaxant effects of the two enantiomers to endothelium removal. Molecular docking studies also demonstrated that (+)-praeruptorin A was in more agreement to nitric oxide synthase pharmacophores than (-)-praeruptorin A. On the other hand, the two enantiomers of praeruptorin A could slightly attenuate the contraction of rat aortic rings induced by internal Ca(2+) release from sarcoplasmic reticulum (SR). These findings indicated that (+)-praeruptorin A and (-)-praeruptorin A exerted distinct relaxant effects on isolated rat aorta rings, which might be mainly attributed to nitric oxide synthesis catalyzed by endothelial nitric oxide synthase.

Isolation of praeruptorins A and B from Peucedanum praeruptorum Dunn. and their general pharmacological evaluation in comparison with extracts of the drug

The root of Peucedanum praeruptorum Dunn. was extracted with solvents at different polarity obtaining three chemical fractions: aqueous (H2O), n-butanol (BuOH) and ethyl acetate (AcOEt). From AcOEt praeruptorins A and B were isolated by column chromatography on silica gel, using toluene/ethyl acetate as eluent, and identified by 1H and 13C NMR analysis. The extracts and the praeruptorins were tested for gross behavioural effects and acute toxicity in mice; the cytotoxicity on Artemia salina Leach and the antimicrobial activity were also evaluated. None of the tested substances evoked behavioural effects or acute toxicity after oral administration in mice; delayed mortality was observed with AcOEt and praeruptorin A only after intraperitoneal administration of high doses (1 g/kg). In Artemia salina test AcOEt, and praeruptorins A and B had LC50 values of 40.2, 121.2 and 34.5 microg/ml, respectively. AcOEt and praeruptorin A showed antimicrobial activity on Streptococcus agalactiae; their MIC values were 250 and 100 microg/ml, respectively.

Effects of Chinese herbal products on mammalian retinal functions

Ocular ischemia and inflammation are two major factors which induce retinal degeneration. Treatment of these diseases has been difficult, though numerous agents have been tried. Natural products could be a good field to venture into because various medicinal plants have been used for centuries to treat circulation stasis, inflammation, visual disturbances, and eyesight failure. Tetramethyl-pyrazine, coumarin, methyl tyramine, rescinnamine, apocynin, and hesperetin are some natural products isolated from Chinese herbs for improving ocular blood flow, particularly in the choroid and retina. For ocular inflammation, at least a dozen natural products are reviewed in this article. Among those, matrine, tetrandrine and osthole draw particular attention, because they are effective mainly as interleukin-1 blockers, but not as arachidonate blockers. As a result, these agents are potent anti-inflammatory agents and are even more potent than the prototype corticosteroid, prednisolone. It is hoped that all aforementioned agents can be used to treat retinopathies resulting from ocular ischemia and/or ocular inflammation. Scoparone, corylifolinin, epigallocatechin-3-0-gallate, esculetin, and lespedezaflavanone A are some natural products which can improve retinal functions measured with electroretinogram's b-wave recovery. Further research should be carried out to relate natural products which can improve ocular blood flow and inflammation to retinal function and vice versa.