Francisco A. Marques

Chemical composition and antimicrobial activity of the essential oils of the Amazon Guatteriopsis species

The essential oils of Guatteriopsis blepharophylla, Guatteriopsis friesiana and Guatteriopsis hispida were obtained by hydrodistillation and analysed by GC and GC/MS. The main compound found in the leaf oil of G. blepharophylla was caryophyllene oxide (1) (69.25%). The leaf oil of G. friesiana contained predominantly beta-eudesmol (2) (51.60%), gamma-eudesmol (3) (23.70%), and alpha-eudesmol (4) (14.56%). The major constituents identified in the leaf of G. hispida were beta-pinene (38.18%), alpha-pinene (30.77%) and (E)-caryophyllene (20.59%). The antimicrobial activity of the essential oils was evaluated against 11 species of microorganisms. The oil of G. friesiana exhibited significant antimicrobial activity for all microorganisms tested, whereas that of G. hispida and G. blepharophyla had potent activity against Rhodococcus equi with MIC of 50 microg mL(-1). The major constituents of each oil were also tested separately, and showed lower activity compared to the oils. Moreover, mixtures of the main constituents, in the same proportions found in G. friesiana and G. hispida oils, did not show the same activity as the original oils.

Alarm pheromone system of stink bug Piezodorus guildinii (Heteroptera: Pentatomidae)

Os compostos utilizados pelo percevejo da soja Piezodorus guildinii como feromonio de alarme foram caracterizados atraves da analise da composicao quimica das secrecoes da glândula metatoracica dos insetos adultos. Alem dos hidrocarbonetos caracteristicos, (E)-2-hexenal e (E)-4-oxo-2-hexenal foram detectados como constituintes majoritarios. Tais compostos ja foram previamente descritos como feromonio de alarme em outras especies de pentatomideos.

Chemical constituents isolated from the bark of Guatteria blepharophylla (Annonaceae) and their antiproliferative and antimicrobial activities

Phytochemical study of the bark of Guatteria blepharophylla (Mart.) Mart. afforded twelve compounds, namely two sesquiterpenes, caryophyllene oxide (1) and spathulenol (3), one xanthone, lichexanthone (2), a mixture of steroids, β-sitosterol (4), and stigmasterol (5), and seven isoquinoline alkaloids, O-methylmoschatoline (6), lysicamine (7), nornuciferine (8), liriodenine (9), isocoreximine (10), subsessiline (11), and isomoschatoline (12). Their structures were established on the basis of spectroscopic methods. Compounds 1-6, 11 and 12 were reported for the first time in this species. The 13C NMR (nuclear magnetic resonance) data for the compounds 11 and 12 are described for the first time in the literature. The antiproliferative activity against human tumour cell lines and antimicrobial activities were investigated for the major compounds. Compound 9 showed significant activity against cell lines of breast (MCF-7, Michigan Cancer Foundation-7), superior to the positive control doxorubicin. Compound 12 presented antifungal activity similar to the positive control nystatin against Candida albicans.

Oxidative coupling of 4-substituted 2-methoxy phenols using methyltributylammonium permanganate in dichloromethane

Abstract Dimers of 4-substituted 2-methoxy phenols were prepared using methyltributylammonium permanganate (MTBAP) in dichloromethane. This methodology allows the selective coupling of such compounds preserving other moieties easily oxidized by permanganate anion in aqueous solution.

7,7-Dimethylaporphine alkaloids from the stem of Guatteriopsis friesiana.

Phytochemical investigation of a methanolic extract of the stem of Guatteriopsis friesiana afforded two new 7,7-dimethylaporphine alkaloids, 6,6a-dihydrodemethoxyguadiscine (1) and guatteriopsiscine (3), together with demethoxyguadiscine (2), liriodenine (4), corypalmine (5), and coreximine (6). Their structures were elucidated on the basis of spectroscopic methods (UV, IR, EIMS, HRESIMS, 1D/2D NMR). The absolute configurations of 1 and 3 were determined from the circular dichroism curves. The presence of 7,7-dimethylaporphine alkaloids in this species is important for the chemotaxonomy of Guatteriopsis. Antimicrobial activity of compounds 1-5 was investigated, and 4 showed activity against Rhodococcus equi, with a MIC value of 10 microg x mL(-1).

Essential Oils from Different Plant Parts of Eucalyptus cinerea F. Muell. ex Benth. (Myrtaceae) as a Source of 1,8-Cineole and Their Bioactivities

Eucalyptus cinerea, known as silver dollar tree, has few descriptions in traditional medicine. Chemical composition and antimicrobial properties of the essential oils of leaves, flowers and fruits, collected seasonally, were determined by GC/MS and disk diffusion/MIC, respectively. 1,8-Cineole was the main compound, particularly in fresh leaves—Spring (74.98%), dried leaves—Spring (85.32%), flowers—Winter (78.76%) and fruits—Winter (80.97%). Other compounds were found in the aerial parts in all seasons: α-pinene (2.41% to 10.13%), limonene (1.46% to 4.43%), α-terpineol (1.73% to 11.72%), and α-terpinyl acetate (3.04% to 20.44%). The essential oils showed antimicrobial activities against bacteria and yeasts, with the best results being found for the dried autumn and winter leaves oils (MIC < 0.39 mg/mL) against Streptococcus pyogenes. For the other tested microorganisms the following MIC results were found: Staphylococcus aureus— Dried leaves oil from summer (0.78 mg/mL), Pseudomonas aeruginosa—Flowers oil from autumn and fruits oil from winter (1.56 mg/mL) and Candida albicans—Flowers oil from autumn and fruits oils from winter and spring (0.78 mg/mL).

Selectivity on the reaction of vinylic tellurides with butyllithium in the presence of carbonyl compounds

Abstract The treatment of isomeric vinylic tellurides 5–7 with butyllithium in THF at −78 °C in the presence of a carbonyl compound such as benzaldehyde or cyclohexanone was studied. High selectivity of the attack at the tellurium atom was observed. In most cases, the corresponding allylic alcohol was obtained as the only (or major) product instead of the alcohols derived by the 1,2 addition of BuLi at the carbonyl compound. Similar results were obtained using the ketenetelluroacetal 14 instead of the vinylic monotellurides.

Production and characterization of alginate-starch-chitosan microparticles containing stigmasterol through the external ionic gelation technique

O estigmasterol, um fitoesterol com diversas atividades farmacologicas, e suscetivel a oxidacao quando exposto ao ar, calor e umidade. Neste contexto, a microencapsulacao e uma forma de protecao contra oxidacao, permitindo a incorporacao do estigmasterol em diversas formas farmaceuticas e aumentar sua absorcao. As microparticulas foram obtidas por gelificacao ionica externa, em uma etapa, utilizando como revestimento polimeros naturais de alginato de sodio, amido de milho e quitosana. As microparticulas apresentaram formato esferico com tamanho aproximado de 1,4 mm. O rendimento foi de 94,87% e a eficiencia media de encapsulacao de 90,42%. A quantidade de estigmasterol no oleo recuperado das microparticulas foi de 9,97 mg/g. O metodo mostrou-se viavel para a microencapsulacao do estigmasterol.

Composition of leaf and rhizome essential oils of Hedychium coronarium Koen. from Brazil.

Abstract Hydrodistillation of fresh leaves and rhizomes of Hedychium coronarium collected in the Atlantic rain forest of southeastern Brazil afforded essential oils in 0.68% and 0.20% yields, respectively. Analysis of the oils by GC and GC/MS revealed as predominant constituents in the leaf oil β-caryophyllene (43.0%), caryophyllene oxide (12.1%) and β-pinene (11.6%,), whereas 1,8-cineole (34.8%), β-pinene (16.7%) and α-terpineol (13.1%) were the major components identified in the rhizome oil.

Synthesis of (±)-africanol

Two diastereomers of africanol, compounds 1a and 1b, were obtained exclusively through a methodology which employed, as the key step, the nBuLi mediated intramolecular cyclization of the vinyl iodide 5. A similar cyclization of 19 provided exclusively the tertiary allylic alcohol 20. Africanol could be prepared, along with its diastereomers 1a and 1b, when ketone 21 was submitted to the cyclization reaction promoted by samarium iodide.