Trypanocidal and antimicrobial activities of Moquinia kingii

Activity of Compounds from Temperate Propolis against Trypanosoma brucei and Leishmania mexicana

Ethanolic extracts of samples of temperate zone propolis, four from the UK and one from Poland, were tested against three Trypanosoma brucei strains and displayed EC₅₀ values < 20 µg/mL. The extracts were fractionated, from which 12 compounds and one two-component mixture were isolated, and characterized by NMR and high-resolution mass spectrometry, as 3-acetoxypinobanksin, tectochrysin, kaempferol, pinocembrin, 4′-methoxykaempferol, galangin, chrysin, apigenin, pinostrobin, cinnamic acid, coumaric acid, cinnamyl ester/coumaric acid benzyl ester (mixture), 4′,7-dimethoxykaempferol, and naringenin 4′,7-dimethyl ether. The isolated compounds were tested against drug-sensitive and drug-resistant strains of T. brucei and Leishmania mexicana, with the highest activities ≤ 15 µM. The most active compounds against T. brucei were naringenin 4′,7 dimethyl ether and 4′methoxy kaempferol with activity of 15–20 µM against the three T. brucei strains. The most active compounds against L. mexicana were 4′,7-dimethoxykaempferol and the coumaric acid ester mixture, with EC₅₀ values of 12.9 ± 3.7 µM and 13.1 ± 1.0 µM. No loss of activity was found with the diamidine- and arsenical-resistant or phenanthridine-resistant T. brucei strains, or the miltefosine-resistant L. mexicana strain; no clear structure activity relationship was observed for the isolated compounds. Temperate propolis yields multiple compounds with anti-kinetoplastid activity.

Applications of Sesquiterpene Lactones: A Review of Some Potential Success Cases

Sesquiterpene lactones, a vast range of terpenoids isolated from Asteraceae species, exhibit a broad spectrum of biological effects and several of them are already commercially available, such as artemisinin. Here the most recent and impactful results of in vivo, preclinical and clinical studies involving a selection of ten sesquiterpene lactones (alantolactone, arglabin, costunolide, cynaropicrin, helenalin, inuviscolide, lactucin, parthenolide, thapsigargin and tomentosin) are presented and discussed, along with some of their derivatives. In the authors’ opinion, these compounds have been neglected compared to others, although they could be of great use in developing important new pharmaceutical products. The selected sesquiterpenes show promising anticancer and anti-inflammatory effects, acting on various targets. Moreover, they exhibit antifungal, anxiolytic, analgesic, and antitrypanosomal activities. Several studies discussed here clearly show the potential that some of them have in combination therapy, as sensitizing agents to facilitate and enhance the action of drugs in clinical use. The derivatives show greater pharmacological value since they have better pharmacokinetics, stability, potency, and/or selectivity. All these natural terpenoids and their derivatives exhibit properties that invite further research by the scientific community.

Guaianolides from the Aerial Parts of Centaurea Hololeuca

Seven guaianolides were isolated from the acetone extract of the aerial parts of Centaurea hololeuca Boiss. The antifeedant activity of the natural compounds (1–7) and of four chloro derivatives (8–11), synthesized from repin (1) and janerin (3) were tested against larvae of Spodoptera littoralis. Cebellin J (6) and chlorojanerin (11) showed significant antifeedant activity at 100 ppm, whereas at this concentration cebellin G (4) and 15-deschloro-15-hydroxychlorojanerin (7) stimulated feeding. Cebellin G (4) stimulated larvae of S. littoralis to feed at low concentration, but deterred feeding at high concentrations. The addition of chlorine to repin (1) resulted in an increase in antifeedant activity.

Cynaropicrin: A Comprehensive Research Review and Therapeutic Potential As an Anti-Hepatitis C Virus Agent

The different pharmacologic properties of plants-containing cynaropicrin, especially artichokes, have been known for many centuries. More recently, cynaropicrin exhibited a potential activity against all genotypes of hepatitis C virus (HCV). Cynaropicrin has also shown a wide range of other pharmacologic properties such as anti-hyperlipidemic, anti-trypanosomal, anti-malarial, antifeedant, antispasmodic, anti-photoaging, and anti-tumor action, as well as activation of bitter sensory receptors, and anti-inflammatory properties (e.g., associated with the suppression of the key pro-inflammatory NF-κB pathway). These pharmacological effects are very supportive factors to its outstanding activity against HCV. Structurally, cynaropicrin might be considered as a potential drug candidate, since it has no violations for the rule of five and its water-solubility could allow formulation as therapeutic injections. Moreover, cynaropicrin is a small molecule that can be easily synthesized and as the major constituent of the edible plant artichoke, which has a history of safe dietary use. In summary, cynaropicrin is a promising bioactive natural product that, with minor hit-to-lead optimization, might be developed as a drug for HCV.

The use of herbs against neglected diseases: Evaluation of in vitro leishmanicidal and trypanocidal activity of Stryphnodendron rotundifolium Mart

The evaluation of the leishmanicidal and trypanocidal activity of the hydroalcoholic extract of the bark of Stryphnodendron rotundifolium Mart. (EHCSR) was carried out to find an alternative treatment for parasitic diseases. EHCSR was prepared and used at four different concentrations (1000, 500, 250, 125 μg/mL) in in vitro assays for activity against Leishmania promastigotes using the species Leishmania brasiliensis and Leishmania infantum and for trypanocidal activity using the epimastigotes of Trypanosoma cruzi. We also tested EHCSR for cytotoxicity against adhered cultured Murine J774 fibroblasts. The tests were performed in triplicate, and the percent mortality of parasites, IC₅₀ and percent toxicity were determined. With regard to anti-leishmania activity against L. infantum, there was a mean mortality of 45% at all concentrations, and against L. brasiliensis, a substantial effect was seen at 1000 μg/mL with 56.38% mortality, where the IC₅₀ values were 1338.76 and 987.35 μg/mL, respectively. Trypanocidal activity was notably high at 1000 μg/mL extract with 82.31% mortality of epimastigotes. Cytotoxicity at the highest extract concentrations of 500 and 1000 μg/mL was respectively 75.12% and 94.14%, with IC₅₀ = 190.24 μg/mL. Despite that the extract has anti-parasitic activity, its substantial cytotoxicity against fibroblasts cells makes its systemic use nonviable as a therapeutic alternative.

Cytochrome P450s from Cynara cardunculus L. CYP71AV9 and CYP71BL5, catalyze distinct hydroxylations in the sesquiterpene lactone biosynthetic pathway

Cynara cardunculus (Asteraceae) is a cross pollinated perennial crop which includes the two cultivated taxa globe artichoke and cultivated cardoon. The leaves of these plants contain high concentrations of sesquiterpene lactones (STLs) among which cynaropicrin is the most represented, and has recently attracted attention because of its therapeutic potential as anti-tumor and anti-photoaging agent. Costunolide is considered the common precursor of the STLs and three enzymes are involved in its biosynthetic pathway: i.e. the germacrene A synthase (GAS), the germacrene A oxidase (GAO) and the costunolide synthase (COS). Here we report on the isolation of two P450 genes, (i.e. CYP71AV9 and CYP71BL5), in a set of ∼19,000 C. cardunculus unigenes, and their functional characterization in yeast and in planta. The metabolite analyses revealed that the co-expression of CYP71AV9 together with GAS resulted in the biosynthesis of germacra-1(10),4,11(13)-trien-12-oic acid in yeast. The co-expression of CYP71BL5 and CYP71AV9 with GAS led to biosynthesis of the free costunolide in yeast and costunolide conjugates in Nicotiana benthamiana, demonstrating their involvement in STL biosynthesis as GAO and COS enzymes. The substrate specificity of CYP71AV9 was investigated by testing its ability to convert amorpha-4,11-diene, (+)-germacrene D and cascarilladiene to their oxidized products when co-expressed in yeast with the corresponding terpene synthases.

Sesquiterpenoids in subtribe Centaureinae (Cass.) Dumort (tribe Cardueae, Asteraceae): distribution, (13)C NMR spectral data and biological properties

Asteraceae Bercht. & J. Presl is one of the biggest and most economically important plant families. The taxonomy and phylogeny of Asteraceae is rather complex and according to the latest and most reliable taxonomic classification of Panero & Funk, based on the analysis of nine chloroplast regions, the family is divided into 12 subfamilies and 35 tribes. One of the largest tribes of Asteraceae is Cardueae Cass. with four subtribes (Carlininae, Echinopinae, Carduinae and Centaureinae) and more than 2500 species. Susanna & Garcia-Jacas have organized the genera of Centaureinae (about 800 species) into seven informal groups, which recent molecular studies have confirmed: 1. Basal genera; 2. Volutaria group; 3. Rhaponticum group; 4. Serratula group; 5. Carthamus group; 6. Crocodylium group; 7. Centaurea group. This review summarizes reports on sesquiterpenoids from the Centaureinae subtribe of the Asteraceae family, as well as the (13)C NMR spectral data described in the literature. It further reviews studies concerning the biological activities of these metabolites. For this work, literature data on sesquiterpenes from the Centaureinae subtribe were retrieved with the help of the SciFinder database and other similar data banks. All entries from 1958 until the end of 2011 were considered. This review is addressed to scientists working in the metabolomics field such as chemists, botanists, etc., the spectroscopic data reported make this work a good tool for structural elucidation, the biological section gives useful information to those who wish to study the structure activity relationships.

Genetic mapping and characterization of the globe artichoke (+)-germacrene A synthase gene, encoding the first dedicated enzyme for biosynthesis of the bitter sesquiterpene lactone cynaropicrin

Globe artichoke (Cynara cardunculus var. scolymus L., Asteraceae) is a perennial crop traditionally consumed as a vegetable in the Mediterranean countries and rich in nutraceutically and pharmaceutically active compounds, including phenolic and terpenoid compounds. Its bitter taste is caused by its high content of sesquiterpene lactones (STLs), such as cynaropicrin. The biosynthetic pathway responsible for STL biosynthesis in globe artichoke is unknown, but likely proceeds through germacrene A, as has been shown for other Asteraceae species. Here, we investigated the accumulation of cynaropicrin in different tissues of globe artichoke, and compared it to accumulation of phenolic compounds. Cynaropicrin concentration was highest in old leaves. A putative germacrene A synthase (GAS) gene was identified in a set of ~19,000 globe artichoke unigenes. When heterologously expressed in Escherichia coli, the putative globe artichoke GAS converted farnesyl diphosphate (FPP) into (+)-germacrene A. Among various tissues assayed, the level of globe artichoke GAS expression was highest in mature (six week old) leaves. A sequence polymorphism within a mapping population parent allowed the corresponding GAS gene to be positioned on a genetic map. This study reports the isolation, expression and mapping of a key gene involved in STL biosynthesis in C. cardunculus. This is a good basis for further investigation of this pathway.

Potent inhibitor scaffold against Trypanosoma cruzi trans-sialidase

The protozoan Trypanosoma cruzi, the causative agent of Chagas' disease, can infect the heart, causing cardiac arrest frequently followed by death. To treat this disease, a potential molecular drug target is T. cruzi trans-sialidase (TcTS). However, inhibitors found to date are not strong enough to serve as a lead scaffold; most inhibitors reported thus far are derivatives of the substrate sialic acid or a transition state analogue known as 2,3-dehydro-3-deoxy-N-acetylneuraminic acid (DANA) with an IC(50) value of more than hundreds of micromolar. Since natural products are highly stereodiversified and often provide highly specific biological activity, we screened a natural product library for inhibitors of TcTS and identified promising flavonoid and anthraquinone derivatives. A structure-activity relationship (SAR) analysis of the flavonoids revealed that apigenin had the minimal and sufficient structure for inhibition. Intriguingly, the compound has been reported to possess trypanocidal activity. An SAR analysis of anthraquinones showed that 6-chloro-9,10-dihydro-4,5,7-trihydroxy-9,10-dioxo-2-anthracenecarboxylic acid had the strongest inhibitory activity ever found against TcTS. Moreover, its inhibitory activity appeared to be specific to TcTS. These compounds may serve as potent lead chemotherapeutic scaffolds against Chagas' disease.

Mode of action of natural and synthetic drugs against Trypanosoma cruzi and their interaction with the mammalian host

Current knowledge of the biochemistry of Trypanosoma cruzi has led to the development of new drugs and the understanding of their mode of action. Some trypanocidal drugs such as nifurtimox and benznidazole act through free radical generation during their metabolism. T. cruzi is very susceptible to the cell damage induced by these metabolites because enzymes scavenging free radicals are absent or have very low activities in the parasite. Another potential target is the biosynthetic pathway of glutathione and trypanothione, the low molecular weight thiol found exclusively in trypanosomatids. These thiols scavenge free radicals and participate in the conjugation and detoxication of numerous drugs. Inhibition of this key pathway could render the parasite much more susceptible to the toxic action of drugs such as nifurtimox and benznidazole without affecting the host significantly. Other drugs such as allopurinol and purine analogs inhibit purine transport in T. cruzi, which cannot synthesize purines de novo. Nitroimidazole derivatives such as itraconazole inhibit sterol metabolism. The parasite's respiratory chain is another potential therapeutic target because of its many differences with the host enzyme complexes. The pharmacological modulation of the host's immune response against T. cruzi infection as a possible chemotherapeutic target is discussed. A large set of chemicals of plant origin and a few animal metabolites active against T. cruzi are enumerated and their likely modes of action are briefly discussed.

Antispasmodic activity of fractions and cynaropicrin from Cynara scolymus on guinea-pig ileum

This study describes the antispasmodic activity of some fractions and cynaropicrin, a sesquiterpene lactone from Cynara scolymus, cultivated in Brazil, against guinea-pig ileum contracted by acetylcholine. The dichloromethane fraction showed the most promising biological effects, with an IC(50) of 0.93 (0.49-1.77) mg/ml. Its main active component, the sesquiterpene lactone cynaropicrin, exhibited potent activity, with IC(50) of 0.065 (0.049-0.086) mg/ml, being about 14-fold more active than dichloromethane fraction and having similar potency to that of papaverine, a well-known antispasmodic agent. The results confirm the popular use of artichoke for the treatment of gastrointestinal disturbances, and encourage new studies on this compound, in order to obtain new antispasmodic agents.