949 resultados para Natural Product Synthesis, Imidazole, regioselective


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Brazil has many species of spiders belonging to Araneidae family however, very little is known about the composition, chemical structure and mechanisms of action of the main venom components of these spiders. The main objective of this work was to isolate and to perform the chemical characterization of a novel beta-carboline toxin from the venom of the spider Parawixia bistriata, a typical species of the Brazilian 'cerrado'. The toxin was purified by RP-HPLC and structurally elucidated by using a combination of different spectroscopic techniques (UV, ESI-MS/MS and H-1 NMR), which permitted the assignment of the molecular structure of a novel spider venom toxin, identified as 1-4-guanidinobutoxy-6-hydroxy-1,2,3,4-tetrahydro-beta-carboline, and referred to here as PwTx-II. This compound is toxic to insects (LD50 = 12 +/- 3 eta g/mg honeybee), neurotoxic, convulsive and lethal to rats (LD50 = 9.75 mg/kg of male Wistar rat). (c) 2005 Elsevier Ltd. All rights reserved.

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The effect was investigated of the K+ channel blocker, glibenclamide, on the ability of Crotalus durissus cumanensis venom (CDCM) to promote peripheral antinociception. This was measured by formalin-induced nociception in male Swiss mice. CDCM (200 and 300 mu g/kg) produced an antinociceptive effect during phase 2 in the formalin test. The effect of CDCM (200 mu g/kg) was unaffected by the ATP-sensitive K+ channel blocker glibenclamide (2 mg/kg). These results suggest that CDCM is effective against acute pain. However, the ATP-sensitive K+ channels pathway is not contributable to the antinoeiceptive mechanism of CDCM.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The present study is aimed to diagnose the current public programs focused on herbal medicines in Brazil by means of in loco visits to 10 programs selected by means of questionnaires sent to 124 municipalities that count on herbal medicine services. The main purpose of the implementation of program programs is related to the development of medicinal herbs. 70% of them are intended for the production of herbal medicines and 50% are aimed to ensure the access of the population to medicinal plants and or herbal medicines. The initiative of the implementation of these programs was related to the managers (60%). The difficulties in this implementation were due to the lack of funding (100%) of the programs. In 60% of the programs, the physicians did not adhere to herbal medicine services due to the lack of knowledge of the subject. Training courses were proposed (80%) to increase the adhesion of prescribers to the system. Some municipalities use information obtained from patients to assess the therapeutic efficiency of medicinal plants and herbal medicines. of the programs underway, cultivation of medicinal plants was observed in 90% and 78% of them adopt quality control. In most programs, this control is not performed in accordance with the legal requirements. The programs focused on medicinal plants and herbal medicines implemented in Brazil face sonic chronic problems of infrastructure, management, operational capacity and self-sustainability, which can be directly related to the absence of a national policy on medicinal plants and herbal medicines.

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Allophylus edulis, commonly called 'Chal chal', is a member of the Sapindaceae occurring in the Uruguayan and Brazilian native flora. During the phytochemical analysis of two Chal chal specimens from two welldifferentiated geographical zones (Assis, São Paulo, Brazil, and Santa Lucia, Canelones, Uruguay), considerable amounts of L-quebrachitol were isolated from both samples. The isolation was carried out from the ethanolic twig extracts obtained by maceration of both vegetal samples. White easily distinguishable crystals were mechanically separated, washed, and characterized by 1D and 2D NMR experiments and by MS data. Such techniques confirmed that the crystals isolated from sources collected in both countries resulted in the same compound, L-quebrachitol, a natural product not previously reported for this species and one that has been investigated as a sugar substitute for diabetics. Worthy of note, the content of L-quebrachitol in A. edulis may be the chemical basis to explain its ethnobotanical uses, since infusions of this plant are used to treat diabetes in the practice of local traditional medicine. (c) 2008 Elsevier Ltd. All rights reserved.

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The new isocoumarin, 9,10-dihydroxy-5, 7-dimethoxy-1H-naphtho(2,3c)pyran-1-one, was isolated from the capitula of Paepalanthus bromelioides. The structure was established by means of the spectral data of the natural product and its derivatives. The natural isocoumarin isolated has strong antibiotic activity. © 1990.

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A novel triterpene; viburgenin (1), has been isolated from an extract of the ripe fruit rinds of Rudgea viburnioides, together with the known saponins, arjunglucoside I and trachelosperosides B-1 and E-l, and the triterpenes trachelosperogenin B (2) and arjungenin. Compound 2 was previously obtained as a product from enzymatic hydrolysis, and it is reported for the first time as a natural product. The structure of compound 1 was determined as 2α,3β,19α,23,24-pentahydroxyurs-12-ene by extensive use of 1D and 2D NMR spectroscopic methods. Compound 1 exhibited moderate antifungal activity against Cladosporium cladosporioides.

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This paper describes a new computer approach for chemotaxonomic studies. The methodology employed enables the search for chemical substructures as taxonomic descriptors using all expert system built with plant natural products. The operation of the system was tested with diterpenes as taxonomic markers in Lamiaceae. © 2001 Elsevier Science Ltd.

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The hexane extract of the stems of Raulinoa echinata afforded the sesquiterpenes germacrene D (6), 1β,6α-dihydroxy-4-(15)-eudesmene (4) and oplopanone (5); the triterpenes squalene, isomultiflorenol (7), isobauerenol (8) and friedelin (9); the protolimonoids melianone (2) and melianodiol (3); and the pyranocoumarin 3-(1′-1′-dimethylallyl)-lomatin (1), which has not been reported previously as a natural product; together with β-sitosterol. The hexane extract and some of these compounds were assayed in vitro against trypomastigote forms of Trypanosoma cruzi. Brine shrimp lethality and antimicrobial activities of the crude extract and pure compounds were also evaluated.

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This work reports the separation of phenolic compounds present in the metabolic extract of the lichen Neuropogon aurantiaco-ater (Usniaceae). The crude extract was fractionated by droplet counter-current chromatography using a solvent mixture of high polarity (chloroform:methanol:water at 43:37:20, in ascending mode). The separation resulted in the isolation of usnic and protocetratic acid, which were identified by TLC, HPLC, and NMR tests.

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Propolis is a natural product collected by honey bees containing, among other biochemical constituents, a variety of flavonoids. Propolis is a folk medicinal employed for treating various diseases. It is alleged to exhibit a broad spectrum of bioactivities. The aim of this study was to evaluate the effect of ethanolic extract of propolis (EEP) of species Plebeia droryana and Scaptotrigonea bipunctata through biochemical parameters. Rats were divided into 4 groups: (G1) untreated; (G2) ethanol treated; (G3) treated EEP of Plebeia droryana; (G4) treated of Scaptotrigonea bipunctata. The EEP (100 mg/kg b. w., daily) was administered orally to the animals, for 30 days. Treatment with EEP for two species showed reduction (p<0,05) in serum alanine aminotransferase, aspartato aminotransferase and alkaline phosphatase activity, compared to control ethanol values. The administration of EEP lowered significantly the serum levels of cholesterol (G3= 48,83±5,7 mg/dL; G4=56,91±6,5 mg/dL) and triacylglycerol (G3=45,17±4,16 mg/dL; G4=46,74± 3,90 mg/dL). The serum concentration of albumin (G3=4,16±0,6 g/dL; G4= 3,61±0,36 g/dL) increased (p<0,05) after the administration of EEP, however, it did not affect total protein and glucose concentration. The data suggest that EEP of two species caused alterations of the biochemical parameters.

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Plants are a valuable source of natural products for the maintenance of human health. The purpose of this paper was the study of immunologic activity of yarrow (Achillea millefolium L.), a largely used plant in popular medicine that has many different properties such as: antiinflammatory, astringent, antiseptic and antispasmodic. Macrophages stimulation was evaluated by the determination of H2O2, NO and TNF-α in supernatants of peritoneal macrophages cultures of mice in the presence of the yarrow leaves extract. The thin layer chromatography of extract was also analyzed, showing rutin. All concentrations showed a moderate release of H2O2 and the concentrations of 6, 8 and 10mg/mL had a higher release of NO. The TNF-a was produced in all concentrations, but the best result was obtained at 4mg/mL. Analyzing the results, it is suggested that the yarrow ethanolic extract can modulate the macrophages activation.

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Communiols E-H (1-4), four new polyketide-derived natural products containing furanocyclopentane, furanocyclopentene, cyclopentene, or γ-lactone moieties, have been isolated from two geographically distinct isolates of the coprophilous fungus Podospora communis. The structures of these compounds were determined by analysis of NMR and MS data. © 2005 American Chemical Society and American Society of Pharmacognosy.

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The biotechnology, biochemical characterization, and protective effects of the himematsutake and shiitake mushrooms were studied for the Thematic Project, from 1998 to 2003. A new species, Agaricus Brasiliens is Wasser et al. (= A. blazei Murrill ss. Heinem.), was proposed for the cultivated lineages in Brazil. Interactions among lineages, substrates, casing layers, and fructification inductions (temperature alternations) significantly increased the productivity of A. brasiliensis in Brazil (from 40 g to 200 g of fresh mushroom kg -1 moist compost). However, pests and diseases (mainly Sciaridae flies and false truffle), drastically reduced the productivity of A. brasiliensis (below 50 g kg -1). Biochemically for each mushroom species, the polar extracts, no polars, and medium polarity presented the same organic substances; however, their concentrations differed as a result of the lineages, maturation of the fruit bodies, and cultivation conditions. In this aspect, concentration of linoleic acid in A. brasiliensis (added to animal food) was related directly to the chemical protection against carcinogenic drugs in mice. Aqueous extracts of Lentinus edodes (= Lentinula edodes (Berk.) Pegler) and A. brasiliensis may be preventive chemical protectors against mutagenic and carcinogenic drugs, depending on the lineage and extraction method (tea or juice). However, immunomodulator effects and tumor reduction were only observed with concentrated fractions (hexanic, methanolic, and ATF extracts). Aqueous extracts of A. brasiliensis and L. edodes have antibiotic-like substances and substances able to act as elicitors of resistance responses in some plants (local and systemic) and show a potential to be used in the alternative control of plant pathogens. © 2005 by Begell House, Inc.

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The chemical investigation of the fruits of Cipadessa fruticosa (Meliaceae) afforded the new limonoid cipadesin B and the known swietemahonolide. From the roots of Cedrela fissilis (Meliaceae) were isolated the limonoid 3β-acetoxycarapin, new as natural product, along with the triterpenes oleanolic and oleanonic acid. These compounds and other six mexicanolide limonoids previously isolated from C. fruticosa showed insecticidal activity against the leaf-cutting ants Atta sexdens rubropilosa. ©2005 Sociedade Brasileira de Química.