Atividade antioxidante e antimicrobiana de extratos de atemoia (Annona cherimola Mill. x A. squamosa L.)

O objetivo deste trabalho foi quantificar os teores de fenóis e flavonoides totais, bem como avaliar as atividades antioxidante e antimicrobiana de extratos obtidos dos talos e folhas de atemoia (A. cherimola Mill. x A. squamosa L.), que pertence à família Annonaceae. A atividade antioxidante foi avaliada pelos métodos de sequestro dos radicais 2,2-difenil-1-picrilhidrazil (DPPH) e 2,2'-azinobis-3-etilbenzotiazolina-6-ácido sulfônico (ABTS), bem como pelo método da cooxidação do β-caroteno/ácido linoleico. A avaliação da atividade antimicrobiana dos extratos foi analisada contra 10 cepas de bactérias. Os resultados da atividade antioxidante dos extratos mostraram que o extrato etanólico dos talos (EEt) foi o antioxidante mais efetivo (IC50 = 10,44 ± 1,25 µg/mL) no método do sequestro do DPPH, bem como no sequestro do radical ABTS (24,81 ± 0,49%). O extrato hexânico das folhas apresentou o melhor percentual de atividade antioxidante no ensaio do β-caroteno/ácido linoleico (41,12 ± 4,35%). Os extratos etanólico dos talos e metanólico das folhas mostraram-se ativos contra cepas de Bacillus cereus, Klebsiella pneumoniae, Staphylococcus aureus resistente à meticilina (MRSA), Staphylococcus aureus e Staphylococcus epidermidis.

QUALIDADE DE AMEIXAS CV. REUBENNEL APÓS TRATAMENTO COM PRODUTOS ALTERNATIVOS,REFRIGERAÇÃO E CLIMATIZAÇÃO

O objetivo deste trabalho foi avaliar a aplicação de produtos alternativos e de refrigeração, com posterior aplicação de etileno, sobre a qualidade de ameixas ‘Reubennel’, a fim de prolongar o período de comercialização. Os produtos aplicados logo após a colheita foram: biomassa cítrica (Ecolife®)- 150 mL (p.c.) 100 L-1 por 30 s; vapor de etanol - 2 mL kg-1 por 2 h (20ºC/80%UR), e cloreto de cálcio (CaCl2) - 1% (p/v) por 10 min. Em seguida, os frutos foram armazenados a 0ºC/95%UR. Após 17 e 33 dias, três caixas de cada tratamento, com 40 frutos cada, foram removidas da câmara de refrigeração, sendo uma das caixas segregada para análises, enquanto as outras duas foram transferidas para 20oC/85%UR por mais 4 dias. Destas caixas, uma de cada tratamento foi submetida à climatização, através da aplicação de etileno (100 uL L-1, 72 h) em minicâmara (200 L). Procedeu-se à avaliação da qualidade dos frutos ao zero; 17; 17+4; 33 e 33+4 dias, através de análises físico-químicas, microbiológicas e sensoriais. Os resultados foram analisados estatisticamente, em delineamento experimental inteiramente casualizado para os produtos alternativos e em fatorial (4x2) para a combinação com a climatização. Concluiu-se que o tratamento pós-colheita das ameixas com vapor de etanol reduz a população microbiana, bem como proporciona incremento dos sólidos solúveis. As ameixas ‘Reubennel’ podem ser armazenadas por até 33 dias sob refrigeração (0ºC/95%UR), seguindo-se a climatização com etileno e,imediatamente, comercializadas.

Contribuições recentes da reação de hidroformilação na síntese de produtos farmacêuticos: parte II

The hydroformylation reaction represents one of the most important C1-chemistry area in the chemical industry. This catalytic process, which has been developed up to now mainly to the production of commodities chemicals, has shown a remarkable potential for the preparation of several categories of specialty chemicals and in particular pharmaceutical compounds. Arylpropanoic acids, various amines containing aryl groups, and intermediates for the preparation of vitamins, carbocyclic and heterocyclic compounds and many other classes of organic molecules endowed with pharmacological activity are currently accessible in good-to-high yields through hydroformylation of selected olefinic substrates. The asymmetric hydroformylation is going to reach the stage of maturity and hence to contribute in solving many troublesome synthetic problems connected with the preparation of pharmacologically active compounds with very high enantiomeric purity. The present survey emphasizes the usefulness of synthesis gas as a starting material in fine chemistry, which is expected to be important for industry.

Determinação da Estereoquímica Relativa de Pimaradienos Através de Produtos de Oxidação

Pimaradienes, including isopimaradienes, with an endocyclic double bond between C-9 and C-11 are uncommon compounds in nature. The diterpenoid pimar-9(11),15-dien-19-oic acid (1) was isolated from Mikania triangularis (Asteraceae) and the correct stereochemistry of 1was established by ¹H and 13C NMR studies of several oxidative products, mainly epoxides, of this compound and its double bond isomers.

Utilização de α,α-Diclorociclobutanonas em Síntese de Produtos Naturais

The preparation and chemical potentiality of a,a-dichlorocyclobutanones as useful intermediates in the total synthesis of natural products are reviewed. Some aspects related to the recent advances reported in the literature about the mechanism of [2+2] cycloaddition reaction between dichloroketene and olefins are also presented.

Safrol e eugenol: estudo da reatividade química e uso em síntese de produtos naturais biologicamente ativos e seus derivados

The chemical reactivity of safrole, eugenol, piperonal, vanillin and derivates toward ozone, aluminium chloride, brominating agents and butyl lithium was investigated. The synthesis of naturally occuring anthraquinones, furonaphthoquinones, naphthoquinones, lignans and pterocarpans from these easily available staring materials is also discussed.

Produtos naturais das esponjas marinhas Aaptos sp., Hymeniacidon aff. heliophila, e do nudibrânquio Doris aff. verrucosa

Herein we describe the isolation of homarine and piridiniumbetaine B from the sponge Aaptos sp. Although homarine has a common occurrence among animals, piridiniumbetaine B was only recently isolated from the marine sponge Agelas dispar. The isolation of piridiniumbetaine B from two taxonomically distant marine sponges corroborate previous assumptions that such betaines should be regarded rather as primary metabolites. We have also isolated (9-[5'-(methylthio)-beta-D-xylofuranosyl]adenine (xylosyl-MTA) from the mantle of a nudibranch identified as Doris aff. verrucosa. The occurrence of xylosyl-MTA in the mantle of this animal strongly suggests that it is the same nudibranch species described for the Mediterranean sea. We have been unable to detect any other compound in the mantle extract of D. aff. verrucosa other than xylosil-MTA and sterols. GC-MS analysis of the sterol fraction from the nudibranch and its prey, the sponge Hymeniacidon aff. heliophila, revealed the occurrence of the ubiquitous sterols, cholesterol, brassicasterol, cholestanol, 24-methylcholesterol and 24-ethylcholesterol, as the only common metabolites, therefore precluding any assumption concerning the sequestration of secondary metabolites by the nudibranch from H. aff. heliophila.

Principais avanços e perspectivas na área de produtos naturais ativos: estudos desenvolvidos no NIQFAR/UNIVALI

This work describes the more promising chemical and pharmacological or biological results obtained with some selected Brazilian medicinal plants, which has been conducted at Núcleo de Investigações Químico-Farmacêuticas (NIQFAR)/UNIVALI in the last five years. It was found that several phytoconstituents exhibit different activities, such as antispasmodic, antiallergic, analgesic, antiinflammatory, antimicrobial and antiviral. Some of them were more potent than some well-known standard drugs used clinically.

Planejamento racional de fármacos baseado em produtos naturais

In the area of drug discovery, natural products represent a myriad of templates for new lead discovery. It is, however, most unlikely that the bioactive principle itself shall become a drug; it is much more likely that a medicinal chemistry project needs to be initiated as soon the potency or selectivity or specificity of the new natural product candidate has been disclosed. Brazil has an enormous biodiversity where just a few has been disclosed. Nevertheless, it urges to initiate a joint collaboration in order to circumvent a major breakdown linking between natural products and medicinal chemistry in this country. This paper is intended to encourage people to follow up one of the most pushing forward enterprise that needs to be settled: the pharmaceutical industry.

Determinação espectrofotométrica de dipirona em produtos farmacêuticos por injeção em fluxo pela geração de íons triiodeto

A flow injection spectrophotometric procedure was developed for the determination of metamizol in pharmaceutical formulations. The system is based on the reaction between metamizol and triiodide generated in the system by mixing iodate and iodide-starch solutions. The absorbance of triiodide-starch complex giving a steady-state baseline value which was monitored at 580 nm. The inverse peaks caused by metamizol samples were measured and there was a direct relationship between absorbance decreasing and metamizol concentration from 1.4 x 10-4 to 7.0 x 10-4 mol L-1. The RSD was 0.45 % for a metamizol solution 4.2 x 10-4 mol L-1 (n = 10) with a detection limit (three-fold blank standard deviation/slope) of 6.0 x 10-5 mol L-1 The feasibility of the system was demonstrated for the determination of metamizol in commercial samples with sixty results obtained per hour. The results obtained for metamizol in pharmaceutical formulations using the proposed flow procedure and those obtained using an iodimetric procedure are in agreement at the 95% confidence level and within an acceptable range of error.

Detecção de adulterações em produtos alimentares contendo leite e/ou proteínas lácteas

A critical review of the most relevant analytical methodologies for quality and authenticity control of dairy products and foods containing milk proteins is presented. Chromatographic, electrophoretic and immunological methods are used for: detection of cow's milk in ewe and goat milks, detection of whey added to milk, detection of caseins and/or whey proteins in non-lactic foods and study compounds resulting from milk proteins degradation. Techniques based on polimerase chain reaction are also suitable for detection of cow's milk on cheeses of ewe and goat milks.

Produtos naturais: atualidade, desafios e perspectivas

This article offers an overview on the historical facts and the recent state of art of Chemistry of Natural Products which, in the course of 25 years of SBQ, have led to the present development of this area in Brazil. In addition, this article deals with the last trends on Natural Products in Brazil and also in developed countries.

Determinação de paracetamol em produtos farmacêuticos usando um biossensor de pasta de carbono modificado com extrato bruto de abobrinha (Cucurbita pepo)

Crude extracts of several vegetables such as peach (Prunus persica), yam (Alocasia macrorhiza), manioc (Manihot utilissima), artichoke (Cynara scolymus L), sweet potato (Ipomoea batatas (L.) Lam.), turnip (Brassica campestre ssp. rapifera), horseradish (Armoracia rusticana) and zucchini (Cucurbita pepo) were investigated as the source of peroxidase (POD: EC 1.11.1.7). Among those, zucchini (Cucurbita pepo) crude extract was found to be the best one. This enzyme in the presence of hydrogen peroxide catalyses the oxidation of paracetamol to N-acetyl-p-benzoquinoneimine which the electrochemical reduction back to paracetamol was obtained at a peak potential of ¾0.10V. A cyclic voltammetric study was performed by scanning the potential from + 0.5 to ¾ 0.5 V. The recovery of paracetamol from two samples ranged from 97.3 to 106% and a rectilinear calibration curve for paracetamol concentration from 1.2x10-4 to 2.5x10-3 mol L-1 (r=0.9965) were obtained. The detection limit was 6.9x10-5 mol L-1 and the relative standard deviation was less than 1.1% for a solution containing 2.5x10-3 mol L-1 paracetamol and 2.0x10-3 mol L-1 hydrogen peroxide (n=12). The results obtained for paracetamol in pharmaceutical products using the proposed biosensor and Pharmacopoeial procedures are in agreement at the 95% confidence level.

Um olhar holístico sobre a química de produtos naturais brasileira

This paper describes a comparative analysis on natural product chemistry between the Brazilian Chemical Society journals and twelve representative international publications in the area. The search using the ISI Web of Knowledge disclosed 41,362 publications in the years 2000-2002 containing at least one researcher from a Brazilian Institution, from which 12% belongs to natural products.

Produtos naturais para o controle da transmissão da dengue: atividade larvicida de Myroxylon balsamum (óleo vermelho) e de terpenóides e fenilpropanóides

The bioassay-guided fractionation of the hexane extract obtained from the medicinal plant Myroxylon balsamum (red oil) was conducted in preparative thin layer chromatography on silica gel. The obtained fractions and some terpenoids and phenylpropanoids were assayed as larvicidal on third instar Aedes aegypti larvae, NPPN colony. The results indicate that the sesquiterpene nerolidol was the active constituent in the extract and that the sesquiterpenes were more active than the monoterpenes and phenylpropanoids utilized in this study. Lipophilicity seems to be an important property for the activity since the compounds with hydroxyl, carbonyl and methoxyl groups were less active. The results confirm also that essential oils can be a good tool for the control of dengue.