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The alkaloid tazopsine

International audience; The chemical investigation of the flowers and twigs of Calliandra calothyrsus (Fabaceae) led to the isolation of three new oleanane-type triterpenoid saponins, named calothyrsusosides AC (13). Their structures were established by direct interpretation of their spectral data, mainly HRESIMS, 1D NMR and 2D NMR (1H, 1H NMR DOSY, 13C NMR, COSY, HSQC, HMBC, HSQC-TOCSY and NOESY) and by comparison with literature data. Compounds 1 and 2 were tested for their antiproliferative activity against two digestive carcinoma human cell lines: Hep3B (hepatocellular carcinoma) and Caco-2 (epithelial colorectal adenocarcinoma). Both compounds exhibited an antiproliferative activity against the Hep3B cell line, with IC50 values of 6.0 and 6.5 μM, respectively, while no effect was detected against the epithelial colorectal adenocarcinoma Caco-2 (CC50 > 25 μM).

Decoction of Strychnopsis thouarsii is used in the Malagasy traditional medicine to combat malaria. We have shown that this traditional remedy prevents malaria infection by targeting Plasmodium at its early liver stage. Bioassay-guided fractionation of S. thouarsii stem barks extracts, using a rodent Plasmodium yoelii liver stage parasites inhibition assay, led to isolate the new morphinan alkaloid tazopsine (1) together with sinococuline (2) and two other new related morphinan analogs, 10-epi-tazopsine (3) and 10-epi-tazoside (4). Structures were characterized by 2D NMR, MS, and CD spectral analysis. Compounds 1-3 were found to fully inhibit the rodent P. yoelii liver stage parasites in vitro.

International audience; Three heterobimetallic gold(I)-ruthenium(II) complexes containing heteroditopic bipyridine-N-heterocyclic carbene (NHC) ligands were synthesized and fully characterized by spectroscopic methods and in one case by single-crystal X-ray diffraction. In addition, the in vitro cytotoxic, antileishmanial, and antimalarial activities of these new heterobimetallic complexes were assessed. Moreover, the photophysical properties of two compounds have been used to localize them in tumor cells by confocal microscopy.

The Estrogen Receptors ERα and ERβ bind cofactor proteins via short LXXLL motifs. The exact regulation and selectivity of these interactions remains an open question and the role of post-translational modifications (PTMs) is virtually unexplored. Here, we designed an X(7)-LXXLL-X(7) T7 phage display library and screened this against four ER protein constructs: the 'naked' ERα and ERβ Ligand Binding Domains (LBDs) and the tyrosine phosphorylated ERα (pY537) and ERβ (pY488) LBDs. The site-selective tyrosine phosphorylated protein constructs were obtained via a protein semi-synthesis approach. Phage display screening yielded preferential sets of peptides. LXXLL peptides with a low pI/acidic C-terminus prefer binding to the naked ERβ over the phosphorylated ERβ analogue and ERα constructs. Peptides with a high pI/basic C-terminus show the opposite behaviour. These findings not only show regulation of the ERβ-cofactor interaction via tyrosine phosphorylation, but also suggest that ERβ and its tyrosine 488 phosphorylation play crucial roles in modulating interactions of coactivators to ERα since the natural Steroid Receptor Coactivators (SRCs) feature LXXLL motifs with acidic C-termini, while the repressor protein RIP140 features LXXLL motifs with basic C-termini. This insight provides explanation for ER transcriptional activity and can lead to more focussed targeting of the ER-coactivator interaction.

Chemical protein synthesis allows the generation of milligram quantities of correctly folded and previously inaccessible tyrosine-phosphorylated estrogen receptor a (ERa) and ß (ERß) ligand binding domains. By using this synthetic strategy, the crystal structure of a post-translationally modified nuclear receptor (pY488 ERß) could be obtained for the first time

Background The global spread of multidrug–resistant malaria parasites has led to an urgent need for new chemotherapeutic agents. Drug discovery is primarily directed to the asexual blood stages, and few drugs that are effective against the obligatory liver stages, from which the pathogenic blood infection is initiated, have become available since primaquine was deployed in the 1950s. Methods and Findings Using bioassay-guided fractionation based on the parasite's hepatic stage, we have isolated a novel morphinan alkaloid, tazopsine, from a plant traditionally used against malaria in Madagascar. This compound and readily obtained semisynthetic derivatives were tested for inhibitory activity against liver stage development in vitro (P. falciparum and P. yoelii) and in vivo (P. yoelii). Tazopsine fully inhibited the development of P. yoelii (50% inhibitory concentration [IC50] 3.1 μM, therapeutic index [TI] 14) and P. falciparum (IC50 4.2 μM, TI 7) hepatic parasites in cultured primary hepatocytes, with inhibition being most pronounced during the early developmental stages. One derivative, N-cyclopentyl-tazopsine (NCP-tazopsine), with similar inhibitory activity was selected for its lower toxicity (IC50 3.3 μM, TI 46, and IC50 42.4 μM, TI 60, on P. yoelii and P. falciparum hepatic stages in vitro, respectively). Oral administration of NCP-tazopsine completely protected mice from a sporozoite challenge. Unlike the parent molecule, the derivative was uniquely active against Plasmodium hepatic stages. Conclusions A readily obtained semisynthetic derivative of a plant-derived compound, tazopsine, has been shown to be specifically active against the liver stage, but inactive against the blood forms of the malaria parasite. This unique specificity in an antimalarial drug severely restricts the pressure for the selection of drug resistance to a parasite stage limited both in numbers and duration, thus allowing researchers to envisage the incorporation of a true causal prophylactic in malaria control programs., A derivative of a morphinan alkaloid, tazopsine, from a plant used against malaria in Madagascar, is active against the hepatic stages ofPlasmodium species., Editors' Summary Background. The parasite that causes malaria has quickly developed resistance to many of the drugs that are commonly used to treat this disease. As a result, new drugs and drug combinations are needed. In some parts of the world where antimalarial drugs are failing due to resistance, or are not available to everyone, people often turn to traditional herbal remedies instead. These traditional plant remedies can be a useful starting point for development of new drugs, but the process of developing effective new drugs from plant remedies is long and complicated. An important initial step is to isolate and identify the active compounds from plants and then see how well these compounds perform against malaria parasites in laboratory tests. If the tests are successful, such compounds could then progress to experiments in animals and possibly eventually human trials. One plant used widely in Madagascar for treatment of malaria is Strychnopsis thouarsii; the traditional remedy consists of the plant stem bark boiled in water. Why Was This Study Done? The group of researchers doing this study wanted to discover candidates for new malaria drugs. They therefore wanted to find out which molecular compounds in the stem bark of S. thouarsii contained antimalarial activity, and what particular stage of the malaria parasite's life cycle these compounds had an effect on. The researchers suspected that the agents in this plant bark had some activity against the “liver stage” of malaria infection in humans. This is the first stage of infection, after a person has been bitten by a malaria-infected mosquito, and before blood cells are invaded by malaria parasites (which then causes the disease symptoms). Very few drugs currently in existence have an effect on the “liver stage” of infection, but activity at this stage would be tremendously useful because it could mean a drug is better for prevention of malaria than others in existence. What Did the Researchers Do and Find? First, the researchers wanted to take the traditional herbal remedy—of S. thouarsii bark boiled in water—and find out precisely which molecule in that remedy was responsible for the antimalarial activity. They therefore used a method called chromatography to progressively separate the herbal extract into its distinct components. At each stage of separation, the extract was checked for activity against malaria using a laboratory test. Inactive extracts were disregarded, and the active component then taken on to a further separation round. After many rounds of separation and testing, the researchers got down to a single, apparently new, molecule that was active against malaria in the laboratory test, and this molecule was named tazopsine (in the Malagasy language the word Tazo refers to malaria). In order to find out how effective the molecule was at killing malaria parasites, the researchers took human or mouse liver cells cultured in the laboratory, infected them with malaria parasites (either the malaria parasite that normally infects humans, or a related species that infects mice), and then added tazopsine at different concentrations. The compound completely killed the malaria parasites even at very low concentrations, and had activity against malaria infecting either liver cells or red blood cells. Tazopsine was then given to mice injected with a species of the malaria parasite. The compound protected most mice against malaria infection when it was used at a dosage level lower than the toxic dose. The researchers then tried making a series of different variants of tazopsine in the hope that some variants would be less toxic, but equally active as, the original compound. They found one variant, named NCP-tazopsine, that was much less toxic but just as active as tazopsine, but only against the malaria infecting liver cells. What Do These Findings Mean? In these experiments a new molecule, tazopsine, was discovered from a Malagasy plant, and it was found to be active against liver-stage malaria parasites, in laboratory experiments and in mice. This molecule or variants of it could in future become candidate antimalarial drugs in humans. However, much work would need to be done before testing could get to that stage. Different variants of molecules related to tazopsine would need to be tested to find one that has low toxicity, and these variants would need to be fully evaluated in animals to see how they are handled in the body before any trials could begin in humans. Additional Information. Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030513 The World Health Organization publishes a minisite containing links to information about all aspects of malaria worldwide, including treatment, prevention, and current programmes for malaria control Medicines for Malaria Venture is a collaboration between public and private organizations (including the pharmaceutical industry) that aims to fund and manage the development of new drugs for treatment and prevention of malaria Wikipedia entries for drug discovery and drug development (note: Wikipedia is an internet encyclopedia that anyone can edit)

New imidazo[1,2-a]quinoxaline derivatives have been synthesised by condensation of an appropriate alpha-aminoalcohol with a quinoxaline followed by intramolecular cyclisation and nucleophilic substitutions. Their phosphodiesterase inhibitory activities have been assessed on a preparation of the PDE4 isoform purified from a human alveolar epithelial cell line (A549). These studies showed potent inhibitory properties that emphasize the importance of a methyl amino group at position 4 and a weakly hindered group at position 1.

Liver cancer, for which hepatocellular carcinoma (HCC) represents the most frequent primitive form, is ranked sixth and third in terms of incidence and death respectively in the world. Its survival rate at 5 years is low (less than 10 %). There is no effective treatment to date, surgical approaches excepted or sorafenib with a gain in survival of 3 months. In view of this limitation of therapeutic alternatives, the search and identification of new molecules of natural origin remain an important issue. In this study, the pharmacological properties of 63 extracts, prepared from Peruvian plants selected upon ethnopharmacological investigations conducted in Peru, were analyzed. The extracts were tested in an in vitro phenotypic screening approach on the human hepatocellular carcinoma cell line, Hep3B, following a 3-step cell analysis: 1- the first step consisted in the determination of a screening score which was defined according to 3 criteria : APE, MIT and OMM. APE refers to the Anti-Proliferative Effect of the extract, MIT to the ability of the extract to modify the MITotic events (by increasing or decreasing the number of cells in mitosis), and OMM refers to the ability of an extract to induce Original Morphological Modifications to the treated cells. The score values ranged from 1 to 27 and a score value of 12 was defined as the threshold. Twenty five extracts exhibited a score value > 12 and were selected for further analysis. 2- the second step consisted in the determination of the cytotoxic effect of the 25 extracts selected from step 1, measured after a 48 hrs incubation time. Of these extracts, 11 showed IC50 values > 50 µg/ml, 10 with IC50 between 15 and 50 µg/ml and 4 with IC50 < 15 µg/ml The 14 extracts which exhibited IC50 values lower than 50 µg/ml were selected for the final step. 3- the third step consisted in studying the extracts inducing original phenotypic changes. This led to the selection of 4 extracts : 2 extracts of different families (Iridaceae and Asteraceae) induced blocking Hep3B cells in prometaphase while 2 other extracts, from the same genus (Asteraceae) induced cytoskeletal reorganization. This latter effect was original since it occurred on cells in interphase and not on mitosis as it can be seen with the classical tubulin inhibitors such as colchicine, vinblastine or paclitaxel. Interestingly, the plants from which come the 4 extracts inducing original phenotypes have been little studied so far either chemically or pharmacologically, suggesting that they may be a source of new molecules of therapeutic interest and/or with original structures. Citation Format: Jean Edouard Gairin, Cedric Lavergne, Maelle Carraz, Valérie Jullian, Geneviève Bourdy, Michel Wright. Screening of extracts from ethnopharmacologically selected peruvian plants in human hepatocarcinoma cell line Hep3B. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3204. doi:10.1158/1538-7445.AM2014-3204