Navegando por Assunto "Alcalóides"

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Acesso aberto (Open Access)
Abordagem fitoquímica, determinação da atividade antiplasmódica in vitro e avaliação preliminar da toxicidade do extrato hidroetanólico das cascas de Aspidosperma excelsum Benth (Apocynaceae)
(Universidade Federal do Pará, 2011) GOMES, Luis Fábio dos Santos; DOLABELA, Maria Fâni; http://lattes.cnpq.br/0458080121943649; VASCONCELOS, Flávio de; http://lattes.cnpq.br/3695753129639448
Malaria is a disease caused by protozoa of the genus Plasmodium. The treatment of malaria is becoming increasingly difficult with the expansion of the cases of parasites resistant to drugs used in therapy. In this context, products isolated from plants have give an important contribution, representing an important source for obtaining new antimalarial drugs. Antiplasmodial activity of alkaloids of plant origin has been widely reported in the literature. Plants of the Apocynaceae family, rich in indole alkaloids have medicinal properties and some large species of the genus Aspidosperma have demonstrated antimalarial potential. Thus, this study aimed to perform a phytochemical approach, evaluate the antiplasmodial activity and toxicity in vitro preliminary of the hydroethanolic extract from the bark of A. excelsum, native of the Amazon region, where it is traditionally used to treat various diseases, including malaria. Antiplasmodial activity in vitro of different concentrations of the extract and alkaloidal and methanolic fractions was evaluated in cultures of P. falciparum W2 by the percentage of inhibition of parasitaemia and the mean inhibitory concentration (IC50) was determined at intervals of 24, 48 and 72 h. The cytotoxicity assay of the extract and alkaloidal fraction was carried out on L929 mouse fibroblasts by MTT method and the testing of acute oral toxicity of the extract was carried out according to the Fixed Dose Procedure adopted by the OECD with small modifications. The phytochemical approach revealed the presence of saponins, reducing sugars, phenols and tannins and alkaloids, and these were confirmed in significant amounts in the alkaloidal fraction with chloroform fraction (C2). Through thin layer chromatography and high performance liquid chromatography of the extract characterized the presence of the indole alkaloid yohimbine. The extract and fractions showed antiplasmodial activity in vitro. The extract showed the best activity in 24 h (IC50 = 5.2 ± 4.1 μg / mL), indicating a good activity schizonticide. Only C2 alkaloidal fraction showed a small but significant cytotoxicity (concentrations higher than 800 μg/mL). The extract not only cytotoxicity but also did not showed any obvious sign of toxicity in acute oral dose of 5000 mg/mL. The results indicate that the extract of Aspidosperma excelsum Benth presents promising potential antimalarial and deserves more detailed studies on antiplasmodial activity, aiming the isolation of active compounds and elucidation of their mechanisms of action.
Acesso aberto (Open Access)
Ação do alcaloide (+)-filantidina sobre o protozoário Leishmania (Leishmania) amazonensis e a célula hospedeira
(Universidade Federal do Pará, 2014-08-14) MORAES, Lienne Silveira de; SILVA, Edilene Oliveira da; http://lattes.cnpq.br/7410116802190343
Leishmaniasis is an antropozoonotic disease caused by parasites of the genus Leishmania. These parasites proliferate primarily within macrophages of mammals and are responsible for promoting a variety of clinical manifestations, such as cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (MCL). The treatment available is chemotherapy, but is limited by toxicity and requires a long term treatment. The study of natural products from plants such as antileishmanial agent currently plays an important role in the search for new drugs for the treatment of leishmaniasis. (+)-phylantidine, is an alkaloid extracted from stem of Margaritaria nobilis of the family Phyllanthaceae. The aim of this study is evaluated the effects of (+)-phylantidine on promastigotes forms of Leishmania (Leishmania) amazonensis and host cell. Antiproliferative activity of promastigotes forms was observed when parasites were treated with 50, 100 e 200 μg/mL of alkaloid for 96 hours, with reduction of 73.75%, 82.50% and 88.75%, respectively when compared with non-treated parasites. In the period of 96 hours it was observed an IC50 of 56.34 μg/mL. Amphotericin B was used as reference drug and reduction of 100% in parasites treated with 0.1 μg/mL was observed after 96 hours. Treatment with the alkaloid promoted important changes in promastigotes that were observed by scanning and transmission electron microscopy. Alterations in cell body, flagellum, kinetoplast, mitochondria, rosette formation, presence of electrodense vesicles suggestive of lipid body and increase in structures like acidocalcisssomes were observed. In the host cell no cytotoxic effect was observed in the macrophages treated with the alkaloid and analysis by scanning electron microscopy showed that the alkaloid promoted an increase in the number of cytoplasmic projections, increased cell volume and spreading. Thus, these results demonstrate that (+)-phylantidine was effective in reducing the growth of the protozoa, without citotoxy effect which may represent a promising natural alternative source for the treatment of leishmaniasis.
Acesso aberto (Open Access)
Alcalóides de Aspidosperma auriculatum Standl
(2003) BARBOSA, Wagner Luiz Ramos; TAVARES, Isabel Cecília de Castro; SOARES, Daniela Cristina
Species from genus Aspidosperma show the presence of indol alkaloids. From Aspidosperma quebracho-blanco Schlecht quebracacidine was obtained1, from A. olivaceum. Schmutz and Hunziker2 isolated olivacine, among others substances. This work reports the determination of the chromatographic profile of alkaloid fractions from Aspidosperma auriculatum, by Thin Layer Chromatography and High Performance Liquid Chromatography. At the Brazilian state Pará this plant species has the vernacular name carapanaúba and is traditionally indicated to heal fever and others affections and also malaria. The plant material - stem bark - was extracted with hydrochloridric acid 5%. Three principal alkaloid fractions were extracted at pH 7, pH 8 and pH 11, which were analysed in suitable systems showing characteristic profiles
Acesso aberto (Open Access)
Alkaloids and volatile constituents from the stem of Fusaea longifolia (Aubl.) Saff. (Annonaceae)
(2005-06) TAVARES, Josean Fechine; BARBOSA FILHO, José Maria; SILVA, Marcelo Sobral da; MAIA, José Guilherme Soares; CUNHA, Emidio Vasconcelos Leitão da
A phytochemical study of the ethanol extract and an extraction of the volatile compounds, performed by means of Clevenger apparatus were carried out with the stem of Fusaea longifolia (Aubl.) Saff. (Annonaceae). The ethanol extract yielded O-methylmoschatoline, isolated for the first time in this species, and stepholidine, reported for the first time in genus Fusaea. The structural identification of the alkaloids was made based on the analysis of their NMR spectra. Through the use of GC and GC-MS, two sesquiterpenoids, a-cadinol (12.5%) and spatulenol (12.0%) were identified as the major constituents of the essential oil.
Acesso aberto (Open Access)
Coumarins and Alkaloids from the Stems of Metrodorea Flavida
(1999) GONÇALVES, Ana Cristina Baetas; ARRUDA, Mara Silvia Pinheiro; MÜLLER, Adolfo Henrique; ARRUDA, Alberto Cardoso
A new coumarin, 5,6-methylenedioxy-7,8-dimethoxycoumarin has been isolated from the stems of Metrodorea flavida, as well as known coumarins and alkaloids. The structures of the new and the known compounds were established by spectral data and by comparison with the literature data.
Acesso aberto (Open Access)
Espectrometria Raman, UV, DOS e Circular Dicroísmo de alcalóides do cigarro
(Universidade Federal do Pará, 2011-02-28) GUEDES, Alberto Monteiro; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
This work is about spectroscopic analysis of some molecular structures present in tobacco (Nicotiana glauca), the base for cigarette, and their interactions with the DNA molecule. According to its importance, among the variety present in the cigarette, the molecules studied were derived from nicotinic acid, nicotinic acid (niacin / vitamin B3), nicotinamide, trigonelline, nicotine, nornicotine and anabasine. The optimizations of these structures were initially obtained in the Hyperchem 7.5 computational software based on the theory of molecular mechanics. Then, they were optimized using the method Density Functional Theory, on the basis B3LYP/ 6-311 + + G (d, p), simulated in software Gaussian 03. Once the optimized structures, we obtained the UV absorption, Raman, Infrared, Circular Dichroism and Density of States spectra using Time-Dependent Density Functional Theory also simulated the in the same software. At the end of this process was also simulated, via molecular mechanics, the interactions of these structures with the DNA molecule in order to verify the potential carcinogenic or not these substances.
Acesso aberto (Open Access)
Estudo fitoquímico e atividade antiplasmódica em Plasmodium falciparum (W2) de Himatanthus articulatus (Vahl) Woodson (Apocynaceae)
(Universidade Federal do Pará, 2014-10-15) VALE, Valdicley Vieira; DOLABELA, Maria Fâni; http://lattes.cnpq.br/0458080121943649; OLIVEIRA, Alaide Braga de; http://lattes.cnpq.br/3719659803766075
The present master thesis describes the phytochemical study and the antiplasmodial activity against Plasmodium falciparum (W2) of Himatanthus articulatus (Vahl) Woodson. The ethanol extract (EEHS) obtained by percolation of the bark powder, gave, after concentration, a precipitate (EEHSP) and a pasty residue that was submitted to lyophilization (EEHS). Fractionation of EEHS was carried out by successively re-extraction with DCM, AcOEt and MeOH under reflux, by acid-base partitioning for separation of alkaloids and by chromatography over silica gel column. Furthermore, the bark powder was extracted with 1 N HCl for the separation of alkaloids. TLC prospection of EEHS and EEHSP was carried out while EEHS, FrDCM EEHS, FrAcOET EEHS, FrMeOH EEHS and FAHS2 DCM were also analyzed by HPLC - DAD. Column chromatography of FrAcOET EEHS afforded a substance (S1). EEHS, the major fraction obtained in its chromatographic column (F71), DCM FAHS2 and S1 were analysed by UPLC-PDA-MS/ESI. Spectroscopic analyses of S1 (IR, UV, MS/ESI, 1H and 13CNMR) allowed its identification as plumieride. Antiplasmodial activity against P. falciparum (W2) was evaluated for EEHS, EEHSP, FrDCM EEHS, FrAcOET EEHS, FrMeOH EEHS, FAHS1 DCM, DCM FAHS2, FAEEHS, FNEEHS, FNHS DCM and S1 by the parasite lactate dehydrogenase (pLDH) method. In the TLC prospection, EEHS and EEHSP showed positive results for polyphenols and tannins, saponins, triterpenes and steroids, alkaloids and flavonoids. EEHS fractions were analyzed by HPLC-DAD showing suggestive peaks of iridoids. Analyses by UPLC-PDA-MS/ESI showed that EEHS contains plumieride as the major substance whose psedomolecular peak was observed at m/z 471 (M + H). S1 was identified as plumeride. Until now it was not reported the presence of alkaloids for the species but spots suggestive of alkaloids were observed on TLC with Dragendorff reagent of FAHS1 DCM, DCM FAHS2, FAEEHS, FNEEHS and FNHS DCM were observed. UV spectra registered online by HPLC-DAD for FAHS2 showed that the major peak is suggestive of a β-carboline alkaloid. UPLC-PDA-MS/ESI analysis of FAHS2 DCM showed an intense peak corresondng to a pseudomolecular ion 329 u that could be possibly attributed to the alkaloid 10-hydroxy-antirine-N-oxide (MM 328 u). The antiplasmodial assays were negative for EEHS, EEHSP, FrDCM EEHS, FrAcOET EEHS, FrMeOH EEHS, S1, FAEEHS, FAHS1 DCM, FNEEHS, FNHS DCM and moderately active (CI50 22,89 μg/mL) for FAHS2 DCM. These results indicate that the antiplasmodial activity might be attributed to the plant alkaloids whose presence in H. articulatus is reported here by the firist time.
Acesso aberto (Open Access)
Plant-derived antimalarial agents: new leads and efficient phythomedicines. Part I. Alkaloids
(2009-12) OLIVEIRA, Alaíde Braga de; DOLABELA, Maria Fâni; BRAGA, Fernão Castro; JÁCOME, Rose Lisieux Ribeiro Paiva; VAROTTI, Fernando de Pilla; PÓVOA, Marinete Marins
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. 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.