Inhibitory effects of furoquinoline alkaloids fromMelicope confusa andDictamnus albus against human phosphodiesterase 5 (hPDE5A)in vitro

Mass spectrometry data on specialized metabolome of medicinal plants used in East Asian traditional medicine

Traditional East Asian medicine not only serves as a potential source of drug discovery, but also plays an important role in the healthcare systems of Korea, China, and Japan. Tandem mass spectrometry (MS/MS)-based untargeted metabolomics is a key methodology for high-throughput analysis of the complex chemical compositions of medicinal plants used in traditional East Asian medicine. This Data Descriptor documents the deposition to a public repository of a re-analyzable raw LC-MS/MS dataset of 337 medicinal plants listed in the Korean Pharmacopeia, in addition to a reference spectral library of 223 phytochemicals isolated from medicinal plants. Enhanced by recently developed repository-level data analysis pipelines, this information can serve as a reference dataset for MS/MS-based untargeted metabolomic analysis of plant specialized metabolites.

The complete chloroplast genome of Dictamnus dasycarpus Turcz. (Rutaceae)

Dictamnus dasycarpus Turcz. 1842 is a medicinal plant of China. Its dry root bark is called BAIXIANPI, which is a common traditional Chinese medicine. Here, we report the complete chloroplast genome of D. dasycarpus. The length of the genome, large single-copy (LSC), small single-copy (SSC), inverted repeat (IR), and GC content was 157,056 bp, 84,497 bp, 18,487 bp, 27,036 bp, and 38.5%, respectively. A total of 132 genes were annotated, including 87 protein coding, eight rRNA, and 37 tRNA genes. Interestingly, 15 genes contained single intron while two others contained two introns. The phylogenetic tree showed the two D. dasycarpus (D. albus) clustered in a clade, which was sister to clade formed by the species of Melicope, Tetradium, Phellodendron, and Zanthoxylum.

Medicinal plants as a potential source of Phosphodiesterase-5 inhibitors: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence and distress caused by erectile dysfunction (ED) to both male and female partners are increasing at a steady rate. ED has now become the most treated sexual disorder for men among young and old age groups due to varying physical and psychological factors. The treatment with synthetic Phosphodiesterase-5 (PDE5) inhibitors are cost-effective but due to adverse effects such as priapism, loss of vision, heart attack and syncope, the daily life patterns of these patients are distressed and hence the need for alternative medicaments or sources are of utmost important. Therefore, the exploration of medicinal plants as PDE5 inhibitors will be worthwhile in tackling the problems as many plant extracts and fractions have been long used as aphrodisiacs and sexual stimulants which may be found to be active against PDE5 enzyme.

AIM OF THE STUDY

To provide a review on the different medicinal herbs traditionally used as natural aphrodisiacs, libido or sexual enhancers which are proven for their PDE5 inhibitory effect.

MATERIALS AND METHODS

Ethnobotanical and scientific information was procured, reviewed and compiled from the literature search of electronic databases and search engines.

RESULTS

A total of 97 medicinal plants exhibiting PDE5 inhibitory effect are reviewed in this paper which is supported by preclinical experimental evidence. Among them, 77 plants have been selected according to their traditional and ethnobotanical uses as aphrodisiacs and the rest are screened according to their effectiveness against predisposing factors responsible for ED and sexual dysfunction such as diabetes and hypertension or due to the presence of phytochemicals having structural similarity towards the identified natural PDE5 inhibitors. In addition, sixteen alkaloids, sixty-one phenolics and eight polycyclic aromatic hydrocarbons have been isolated or identified from active extracts or fractions that are exhibiting PDE5 inhibitory activity. Among them, isoflavones and biflavones are the major active constituents responsible for action, where the presence of prenyl group for isoflavones; and the methoxy group at C-5 position of flavones are considered essential for the inhibitory effect. However, the prenylated flavonol glycoside, Icariin and Icariside II isolated from Epimedium brevicornum Maxim (hory goat weed) are the most effective inhibitor, till date from natural sources. Traditional medicines or formulations containing extracts of Ginkgo biloba L., Kaempferia parviflora Wall. ex Baker, Clerodendrum colebrookianum Walp., Eurycoma longifolia Jack and Vitis vinifera L. are also found to be inhibitors of PDE5 enzyme.

CONCLUSION

The review suggests and supports the rational use of traditional medicines that can be further studied for the development of potential PDE5 inhibitors. Many traditional medicines are still used in various regions of Africa, Asia and South America that are poorly characterized and experimented. Despite the availability of a vast majority of traditional formulations as aphrodisiacs or sexual stimulants, there exists a need for systemic evaluation on the efficacy as well as the mechanism of action of the herbal constituents for the identification of novel chemical moieties that can be further developed for maximum efficacy.

Inhibition of UDP-glucuronosyltransferases by different furoquinoline alkaloids

Herbs are often administered in combination with therapeutic drugs, raising the possibility for herb-drug interactions (HDIs). Furoquinoline alkaloids are found in Rutaceae plants, which are structurally similar and have many medicinal properties. This study aims to investigate the inhibition of four furoquinoline alkaloids on the activity of UDP-glucuronosyltransferases (UGTs).The recombinant UGTs-catalyzed glucuronidation metabolism of 4-methylumbelliferone (4-MU) was utilized to investigate the inhibition potential. Inhibition type and parameters were determined, and in silico docking was employed to elucidate the inhibition difference of furoquinoline alkaloids towards UGTs.Dictamine, haplopine, γ-fagarine and skimmianine strongly inhibited UGT1A3, UGT1A7, UGT1A9 and UGT2B4, respectively. Among them, dictamnine inhibited more than 70% of the four UGTs. Inhibition kinetics determination showed that they all exerted competitive inhibition, and the inhibition kinetic constant (K_i) was determined to be 8.3, 7.2, 3.7 and 33.9 μM, respectively. In vitro-in vivo extrapolation (IVIVE) was employed to demonstrate the inhibition possibility for four alkaloids. Skimmianine was proved to be more suitable for clinical application. In silico docking study indicated that the hydrophobic interactions played a key role in the inhibition of furoquinoline alkaloids towards three of the four UGTs. In conclusion, monitoring the interactions between furoquinoline alkaloids and drugs mainly undergoing UGTs-catalyzed metabolism is necessary.

At-line LC-QTOF-MS micro-fractionation of Derris scandens (Roxb.) Benth, coupled to radioassay for the early identification of PDE5A1 inhibitors

INTRODUCTION

Chromatographic techniques coupled with bioassays are popularly used for the detection of bioactive compounds in natural products. In this study phytochemicals responsible for showing Phosphodiesterase type 5 (PDE5) inhibitory activity in Derris scandens were studied using at-line method.

OBJECTIVE

The objective of this study was to develop an at-line liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) micro-fractionation method for rapid separation and identification of PDE5A1 inhibitors in 95% ethanolic extract of D. scandens.

METHODOLOGY

Initially, the correlation between LC-MS and PDE5A1 inhibitory activity was studied using three concentrations of 1:1 mixture of sildenafil and derrisisoflavone A; PDE5A1 inhibitors. The mixture was separated by high-performance liquid chromatography (HPLC) column and the eluent was split into two flows in the ratio of 1:9. The major part was collected in a 96-well plate, in each well consecutively every 30 s. The minor part was fed into an electrospray ionisation (ESI)-QTOF-MS system. After subsequent solvent removal, the collected micro-fractions were subjected to radioassay to determine PDE5A1 inhibition.

RESULTS

The result showed, PDE5A1 inhibitory activities of the micro-fractions were observed in a dose response manner and found to be in agreement with an off-line study. Similarly, 95% ethanolic extract of D. scandens was subjected to the at-line LC-QTOF-MS micro-fractionation developed, resulting in separation and tentative identification of 25 compounds with PDE5A1 inhibitory activity. Most of the compounds contained prenylated isoflavone skeleton. Additionally, the active micro-fractions also showed selectivity on PDE5A1 over PDE6 and PDE1B.

CONCLUSION

Our results demonstrated that the at-line coupled LC-QTOF-MS micro-fractionation with PDE5A1 inhibitory assay is a valuable tool for identifying PDE5A1 inhibitors from complex extracts.

Anti-inflammatory effects of a methanol extract of Dictamnus dasycarpus Turcz. root bark on imiquimod-induced psoriasis

BACKGROUND

The root bark of Dictamnus dasycarpus Turcz. has been successfully used for the treatment of inflammatory skin conditions such as eczema and pruritus. However, the anti-psoriatic effect of this plant has not until now been investigated.

METHODS

The aim of this project was to investigate whether a methanol extract of Dictamnus dasycarpus Turcz. root bark (MEDD) can be used as a therapeutic agent for psoriasis in C57BL/6 mice model of imiquimod (IMQ)-induced psoriasis. IMQ and MEDD was applied to mouse skin continuously for 7 days. The skin phenotype and the levels of inflammatory cytokines, such as interferon (IFN)-γ and interleukin (IL)-17, were analyzed. The immune cell population was determined by flow cytometry, and STAT1 and 3 protein levels were measured.

RESULTS

An alleviation of scaly skin phenotype, immune cell infiltration in the dermis, and epidermal hyperplasia was observed after daily MEDD treatment in the lesion-affected area. It was also found that MEDD reduced IL-17 cytokine levels decreased by 44.37% (p < 0.05), the number of IL-17-producing Th17 cells and γδT cells, and the size of the Th1 population secreting IFN-γ decreased by 45.98, 62.21, and 44.42%, respectively (p < 0.05), compared with the vehicle control group. STAT3 signals, associated with IL-17 are also reduced by MEDD.

CONCLUSIONS

An anti-psoriatic effect of MEDD was observed, as determined by decreased skin inflammation, reduced number of inflammatory cytokines, and a smaller population of inflammatory cells. These results contribute to the validation of the use of MEDD in the treatment of psoriasis.

Interactions of a medicinal climber Tinospora cordifolia with supportive interspecific plants trigger the modulation in its secondary metabolic profiles

Tinospora cordifolia (TC) is scientifically proven immunomodulatory drug being used for centuries. Ancient literature reported that inter-specific interactions change medicinal properties of TC. Thus, the current study is aimed to understand the influence of interspecific biotic interactions on chemo-profiles of TC. To explore it, TC samples collected from six co-occurring plants, i.e. Azarditchita indica, Acacia nilotica, Albezia lebbeck, Ficus benghalensis, Tamarandus indica and Acacia leucophloea were analyzed by HPLC-ESI-QTOF-MS. Mass data were subjected to multivariate analysis. Support vector machines (SVMs) was found to be best classifier (r² < 0.93). Data analysis showed the specific compounds in all TC due to inter-specific interactions. Data were further analyzed with SNK post-hoc test followed by permutative (n = 50) Bonferroni FDR multiple testing correction. The compound without any missing values reduced the number of variables to 133 (p < 0.01). Statistical analysis revealed that TC having interactions with A.lebbeck and A. nilotica formed the most distant groups. However, TC co-occurred with A. indica showed the highest number of up-regulated metabolites, including jatrorrhizine, chrysin, peonidin, 6-methylcoumarin and some terpenoids. Some metabolites, including jatrorrhizine and magnoflorine were quantified to confirm the accuracy of qualitative analysis. Results demonstrated the influence of inter-specific biotic interactions on TC chemo-profiles, hence its medicinal properties.

Biologically active quinoline and quinazoline alkaloids part I

Quinoline and quinazoline alkaloids, two important classes of N-based heterocyclic compounds, have attracted tremendous attention from researchers worldwide since the 19th century. Over the past 200 years, many compounds from these two classes were isolated from natural sources, and most of them and their modified analogs possess significant bioactivities. Quinine and camptothecin are two of the most famous and important quinoline alkaloids, and their discoveries opened new areas in antimalarial and anticancer drug development, respectively. In this review, we survey the literature on bioactive alkaloids from these two classes and highlight research achievements prior to the year 2008 (Part I). Over 200 molecules with a broad range of bioactivities, including antitumor, antimalarial, antibacterial and antifungal, antiparasitic and insecticidal, antiviral, antiplatelet, anti-inflammatory, herbicidal, antioxidant and other activities, were reviewed. This survey should provide new clues or possibilities for the discovery of new and better drugs from the original naturally occurring quinoline and quinazoline alkaloids.

Medicinal uses, phytochemistry and pharmacology of the genus Dictamnus (Rutaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Seven species from the genus Dictamnus are distributed throughout Europe and North Asia and only two species grow in China. One is Dictamnus dasycarpus Turcz., which could be found in many areas of China and has been recorded in Chinese Pharmacopoeia. The other is Dictamnus angustifolius G. Don ex Sweet, which is only present in Xinjiang province and has been used as an alternative for Dictamnus dasycarpus in the local for the treatment of rheumatism, bleeding, itching, jaundice, chronic hepatitis and skin diseases. The present paper reviewed the traditional uses, phytochemistry, pharmacology and toxicology of the genus Dictamnus.

MATERIALS AND METHODS

Information on the Dictamnus species was collected from classic books about Chinese herbal medicine and globally accepted scientific databases including PubMed, Elsevier, ASC, Scopus, Google Scholar, Web of Science, CNKI and others.

RESULTS

About 170 chemical compounds, which include quinoline alkaloids, limonoids, sesquiterpenes, coumarins, flavonoids and steroids, have been isolated from the genus Dictamnus. The characteristic and active constituents of Dictamnus species are considered to be quinoline alkaloids and limonoids, which exhibited a broad spectrum of biological activities such as anti-cancer, anti-inflammation, anti-microbe, anti-platelet-aggregation, vascular-relaxation, anti-insect, anti-HIV, anti-allergy and neuroprotection. Moreover, quinoline alkaloids and limonoids could be used as quality control markers to distinguish different species from the genus Dictamnus. However, there were also some reports on the toxic hepatitis and phototoxic effect of Dictamnus species, and the related research needs to be further studied.

CONCLUSION

In this review, we summarized the chemical constituents, pharmacology, quality control and toxicology of the species from genus Dictamnus. Phytochemical investigations indicated that quinoline alkaloids and limonoids were the major bioactive components with potential cytotoxic, neuroprotective, anti-inflammatory, antimicrobial, anti-platelet-aggregation and vascular relaxing activities. These two kinds of compounds have attracted great interests in the past few years and may have great potential to be new drug lead compounds.

Antiproliferative glabretal-type triterpenoids from the root bark of Dictamnus dasycarpus

Four new glabretal-type triterpenoids, dictabretols A-D (1-4), were isolated by activity-guided fractionation from the root bark of Dictamnus dasycarpus T. (Rutaceae) using an in vitro antiproliferative assay on T cells using splenocytes. The structures of these compounds were determined by spectroscopic methods, including 2D NMR experiments. Compounds were evaluated for their immunosuppressive activity on T cells and demonstrated inhibition of proliferation of activated T cells, up to IC50 of 1.5μM.

Anti-inflammatory activity of the ethanol extract of Dictamnus dasycarpus leaf in lipopolysaccharide-activated macrophages

Background

Dictamnus dasycarpus is widely used as a traditional remedy for the treatment of eczema, rheumatism, and other inflammatory diseases in Asia. The current study investigates the molecular mechanism of anti-inflammatory action of the ethanol extract of Dictamnus dasycarpus leaf (DE) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells.

Methods

Nitric oxide (NO) production was assessed by Griess reaction and the mRNA and protein expressions of pro inflammatory cytokines, transcription factor, and enzymes were determined by real-time RT-PCR and immunoblotting analysis.

Results

DE (0.5 and 1 mg/mL) suppressed the NO production by 10 and 33%, respectively, compared to the untreated group in LPS-stimulated RAW 264.7 cells. DE (0.5 and 1 mg/mL) reduced the mRNA expression of key transcription factor nuclear factor-κB by 7 and 24%, respectively compared to the untreated group in LPS activated macrophage. The pro inflammatory cytokines such as tumor necrosis factor α and interleukin 1β were also decreased by DE treatment. Moreover, the protein expression of pro inflammatory enzymes, inducible nitric oxide synthase and cyclooxygenase 2 were also dramatically attenuated by DE in a dose dependent manner.

Conclusions

These results suggest that Dictamnus dasycarpus leaf has a potent anti-inflammatory activity and can be used for the development of new anti-inflammatory agents.

Quinoline, quinazoline and acridone alkaloids

This review covers the isolation, structure determination, synthesis and biological activity of quinoline, quinazoline and acridone alkaloids from plant, microbial and animal sources: 134 references are cited.

Monoamine oxidase inhibitory coumarins from the aerial parts ofDictamnus albus

The methanol extract from the aerial parts of Dictamnus albus was active in inhibiting monoamine oxidase (MAO) from the mouse brain. Activity-guided fractionation led to the isolation of four known coumarins, 7-(6'R-hydroxy-3', 7'-dimethyl-2'E, 7'-octadienyloxy) coumarin (1), auraptene (2), umbelliferone (3), and xanthotoxin (4), as active compounds along with an inactive alkaloid, skimmianine (5). Compounds 1 and 2 inhibited MAO activity in a concentration-dependent manner with IC50 values of 0.7 and 1.7 microM, respectively. Compounds 1 and 2 showed a slight and potently selective inhibitory effect against MAO-B (IC50 0.5 and 0.6 microM, respectively) compared to MAO-A (IC50 1.3 and 34.6 microM, respectively). According to kinetic analyses derived by Lineweaver-Burk reciprocal plots, compounds 1 and 2 exhibited a competitive inhibition to MAO-B.