ChemInform Abstract: First Enantioselective Total Synthesis of (-)-Tejedine (original) (raw)
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Medicinal Chemistry Research, 2008
A series of carbazole derivatives with promising pharmacological properties has been prepared using either an iron-mediated or a palladium-catalyzed synthetic approach. The carbazole alkaloids carbazoquinocin C, carbazomadurin A and B, epocarbazolin A and B, neocarazostatin B, and carquinostatin A are antioxidants acting as free-radical scavengers. Thus, they represent potential lead compounds for the development of novel drugs against diseases initiated by oxygen-derived free radicals. Initiated by the first naturally occurring carbazole alkaloids with antituberculosis (anti-TB) activity, clausine K and micromeline, a study on the structure–activity relationships for anti-TB-active carbazole derivatives has been carried out. The 6-oxygenated carbazoles glycozoline and glycozolinine show antibiotic activity towards several microorganisms. The 7-oxygenated carbazole siamenol exhibits anti-HIV activity.
Plant-derived antimalarial agents: new leads and efficient phythomedicines. Part I. Alkaloids
Anais da Academia Brasileira de Ciências, 2009
Malaria remains one of the most serious world health problem and the major cause of mortality and morbidity in the endemic regions. Brazil is among the 30 high-burden countries and most of the cases occur in the Legal Amazonian Region. New chemotherapeutical agents are needed for the treatment of malaria. Many plant species are used in traditional medicines of malarious countries and a relatively few number of these have been investigated for evaluation of their antimalarial effect. Still lower is the number of those that have had the active natural compounds isolated and the toxicity determined. This area is, then, of great research interest. A discovery project of antimalarial natural products from plants traditionally used to treat malaria must include in vitro and in vivo assays as well as bioguided isolation of active compounds. The final products would be antimalarial chemical entities, potential new drugs or templates for new drugs development, and/or standardized antimalarial extracts which are required for pre-clinical and clinical studies when the aim is the development of effective and safe phythomedicines. This review discusses these two approaches, presents briefly the screening methodologies for evaluation of antimalarial activity and focuses the activity of alkaloids belonging to different structural classes as well as its importance as new antimalarial drugs or leads and chemical markers for phytomedicines.
The Supercritical Fluid Extraction of Alkaloids from Papaya (Carica papaya L. var. Eksotika) Leaves
Since the isolation procedures are easy, many of the earliest pure compounds isolated with biological activity were alkaloids. The nitrogen molecules in plant cells generally make the compound alkaline which make alkaloids exist in a salt form in plants. Thus, alkaloids are often extracted with water and/or acid solution system and then recovered as crystalline material by treatment using a base. The alkaloid carpaine was extracted from various part of Carica papaya L. var. Eksotika from field grown samples namely leaves, petiole and fruit peel, and from in vitro samples namely leaves, petiole, suspension cells and suspension liquid with only one artifact of impurity detected i.e. dehydrocarpaine II. Supercritical fluid extraction was analysed to obtain pure and high yield of carpaine compound as compared to conventional acid base extraction method. The ratio of ethanol/water/acetic acid used at 94.5:5:0.5 (v/v/v) was confirmed to be a better solvent system for carpaine extraction since only one pseudocarpaine i.e. dehydrocarpaine II was extracted together with carpaine. In this study, the application of single fluid of carbon dioxide in supercritical fluid extraction procedure generated pure and higher yield of carpaine compound. Additional centrifugation step should have contributed to a higher purity of the extracted carpaine.
Antibacterial activity of alkaloids from Sida acuta
African Journal of …, 2006
Sida acuta is a shrub indigenous to pantropical regions. The plant is widely used for its various pharmacological properties. Among compounds of pharmacological interest occurring in the plant, are indoloquinoline alkaloids. The aim of the present study was to investigate the antimicrobial activity of alkaloids of S. acuta from Burkina Faso. The alkaloids had a good antimicrobial activity against the test microorganisms. In the agar-well diffusion assay, highest inhibition zone diameters were recorded with Gram-positive bacteria. The broth microdilution assay gave minimal inhibitory concentration values ranging from 16 to 400 µg/ml and minimal bactericidal concentration values ranging from 80 to up to 400 µg/ml. The gas chromatography-mass spectrometry analysis of the same alkaloids led to the identification of cryptolepine and quindoline as the major components.
UV and EMS induced mutations affecting synthesis of alkaloids and lipase in Penicillium roquefortii
Mutants of a Penicillium roquefortii strain were obtained by ultraviolet irradiation (UV) and ethylmethansulfonate (EMS). Based on alkaloid production, the mutant strains could be divided into four groups: (1) unable to synthesize alkaloids, (2) with a non functional chain of clavin formation, (3) with roquefortine and 3,12-dihydroroquefortine that were not found in the alkaloid fraction and with new compounds, that were not shown in the wild type strain. These data indicate the presence of not less than three different pathways of alkaloids formation in Penicillium roquefortii. On the other hand, all selected mutants produced more lipase than the wild type strain, when using olive oil as a substrate; when cotton seed oil was used many mutant strains produced less lipase activity than the parent strain.
Huperzine A from Huperzia species--an ethnopharmacolgical review
Journal of ethnopharmacology, 2007
Huperzine A (HupA), isolated originally from a traditional Chinese medicine Qiang Ceng Ta, whole plant of Huperzia serrata (Thunb. ex Murray) Trev., a member of the Huperziaceae family, has attracted intense attention since its marked anticholinesterase activity was discovered by Chinese scientists. Several members of the Huperziaceae (Huperzia and Phlegmariurus species) have been used as medicines in China for contusions, strains, swellings, schizophrenia, myasthenia gravis and organophosphate poisoning. HupA has been marketed in China as a new drug for Alzheimer's disease (AD) treatment and its derivative ZT-1 is being developed as anti-AD new drug candidate both in China and in Europe. A review of the chemistry, bioactivities, toxicology, clinical trials and natural resources of HupA source plants is presented.
Antiplasmodial and antimycobacterial cyclopeptide alkaloids from the root of Ziziphus mauritiana
Phytochemistry, 2011
Investigation of the MeOH extract obtained from the root of the Ziziphus mauritiana grown in Thailand resulted in the isolation of two 14-and 13-membered cyclic alkaloids, mauritine L (1) and mauritine M (2), and three known cyclopeptide alkaloids, nummularines H (3), B (4) and hemsine A (5). Their structures were elucidated on the basis of extensive NMR spectroscopic analysis. The first single crystal X-ray diffraction study of the 13-membered ring cyclopeptide, nummularine B methiodide (4 0 ), revealed all S configurations on the amino acid residues. The isolated alkaloids exhibited potent antiplasmodial activity against the parasite Plasmodium falciparum with the inhibitory concentration (IC 50 ) ranging from 3.7 to 10.3 lM. Compounds 2 and 3 also demonstrated antimycobacterial activity against Mycobacterium tuberculosis with the MIC of 72.8 and 4.5 lM, respectively.
NaturallyoccurringplantisoquinolineN-oxidealkaloids:TheirpharmacologicalandSARactivities
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