Showing papers by "Angelo C. Pinto published in 2010"

Chemical defenses against generalist fish predators and fouling organisms in two invasive ahermatypic corals in the genus Tubastraea

Abstract: The introduction of exotic marine species has caused considerable economic and ecological damage around the world Some of these species possess adaptations such as secondary metabolites which facilitate their successful invasion into new areas In this study we tested two hypotheses: (i) crude extracts produced by two invasive hard corals Tubastraea coccinea and Tubastraea tagusensis, introduced to the southwest Atlantic, inhibit predation by generalist fish; (ii) substances found in the crude extracts of both species reduce or enhance the settlement of other organisms In an in situ palatability bioassay the extract of T tagusensis reduced predation by generalist fish The extracts of both species of coral showed species-specific effects on fouling organisms in in situ gel plate bioassays Control and extract plates had similar total cover, although plates with extracts had significantly fewer Cladophora sp, and Lithophyllum sp was only detected on control gels In contrast, a hydrozoan was only found on plates with extracts and overall community ordination demonstrated clear differences in the fouling communities between treatments These results demonstrate that both coral species have chemical substances which can bring about a negative interaction with potential fish predators and competitors such as algal and invertebrate foulers and the advantage gained could explain their success in invading new regions to the detriment of local fauna and flora

The inhibition of paw oedema formation caused by the oil of Copaifera multijuga Hayne and its fractions

Abstract: Two oils exuded from a Copaifera multijuga Hayne tree (Leguminosae-Caesalpinoideae), collected from the same plant, but in different periods of the year, and the hexanic, dichloromethanic and methanolic fractions of one of these oils were analysed by high-resolution gas chromatography (HRGC) and HRGC coupled with mass spectrometry (HRGC-MS). In addition, the in-vivo preliminary anti-oedematogenic actions of the oil and some fractions of it were assessed against carrageenan- and bradykinin-induced oedema formation in the rat paw. Twenty-seven sesquiterpenes and six diterpenes were identified, beta-caryophyllene, alpha-copaene and copalic acid being the main components. The dichloromethanic and methanolic fractions obtained from C. multijuga oil given by the intraperitoneal route caused a significant inhibition of paw oedema caused by carrageenan with inhibition of 49 +/- 13% and 64 +/- 9 %, respectively. Likewise, dexamethasone (the positive control drug) also greatly inhibited carrageenan-induced paw oedema formation (60 +/- 4% at 2 h). The hexanic fraction also significantly inhibited (50 +/- 6%) the paw oedema formation caused by bradykinin. These results suggest the presence of still non-identified active terpene compounds in the oil of C. multijuga that exhibit anti-oedematogenic properties. Of note, the yield of these compounds and the pharmacological actions of the oil, exhibited great seasonal variations, a relevant aspect that should be carefully observed for the correct medicinal use of this plant by the population.

The lipid-lowering effect of trans-dehydrocrotonin, a clerodane diterpene from Croton cajucara Benth. in mice fed on high-fat diet.

Abstract: The clerodane diterpene trans-dehydrocrotonin extracted and isolated from the stem bark of Croton cajucara Benth. was investigated for its lipid-lowering effect in mice fed on a high-fat diet. Mice fed on a high-fat diet for a two-week period demonstrated significantly increased blood levels of total cholesterol and triglycerides, compared with normal controls. Oral treatment with trans-dehydrocrotonin at a dose of 25 or 50 mg kg 1 daily markedly suppressed the high-fat-diet associated rise in total cholesterol and triglyceride levels. The hypocholesterolaemic effect of trans-dehydrocrotonin was more prominent at the dose of 50 mg kg 1 with significant decreases in high-density lipoprotein, very-low-density lipoprotein and low-density lipoprotein cholesterol levels. The lower atherogenic index of the trans-dehydrocrotonin-treated groups suggests the hypolipidaemic potential of this plant-based drug. These results indicate that orally administered trans-dehydrocrotonin is effective in suppressing high-fat-diet-induced hyperlipidaemia in mice and suggest its likely beneficial use as anti-atherogenic agent.

Chemical composition and release in situ due to injury of the invasive coral tubastraea (Cnidaria, Scleractinia)

Abstract: Defensive chemistry may be used against consumers and competitors by invasive species as a strategy for colonization and perpetuation in a new area. There are relatively few studies of negative chemical interactions between scleratinian corals. This study characterizes the secondary metabolites in the invasive corals Tubastraea tagusensis and T. coccinea and relates these to an in situ experiment using a submersible apparatus with Sep-Paks® cartridges to trap substances released by T. tagusensis directly from the sea-water. Colonies of Tubastraea spp were collected in Ilha Grande Bay, RJ, extracted with methanol (MeOH), and the extracts washed with hexane, dichloromethane (DCM) and methanol, and analyzed by GC/MS. Methyl stearate and methyl palmitate were the major components of the hexane and hexane:MeOH fractions, while cholesterol was the most abundant in the DCM and DCM:MeOH fractions from Tubastraea spp. The organic material retained in Sep-Paks® cartridges was tentatively identified as hydrocarbons. There was a significant difference between treatments and controls for 1-hexadecene, n-hexadecane and n-eicosane contents. The production of defensive substances by the invasive corals may be a threat to the benthic communities of the region, which include endemic species.

Cytotoxicity and antibacterial studies of iridoids and phenolic compounds isolated from the latex of Himatanthus sucuuba

Abstract: The latex of Himatanthus sucuuba (Spruce) Woodson, used popularly in the Amazon for the treatment of tumors, gastritis, inflammations and infections, was evaluated for cytotoxicity and antibacterial activities. The iridoid lactones, plumericin and isoplumericin were isolated from latex by bioassay fractionation and were found to be associated with DNA damage. Gallic acid exhibited the highest antimicrobial activity among the phenolic compounds isolated from the aqueous fraction. The compounds associated to cytotoxicity and antimicrobial activities could be responsible to the effects of this species used in traditional medicine. Key words : Himatanthus sucuuba , iridoids, phenolics, cytotoxicity, antibacterial.

Counter-Current Chromatography Separation of Isatin Derivatives using the Sandmeyer Methodology

Abstract: A rapid and efficient method, using high-speed counter-current chromatography (HSCCC) technique, was developed for the separation of isomeric isatin derivatives, prepared following the Sandmeyer route. The biphasic solvent system composed of hexane:ethyl acetate:ethanol:water 1:0.5:0.5:1 (v/v/v/v) was used for all separations.

Synthesis, electrochemical studies and anticancer activity of ferrocenyl oxindoles

Abstract: A series of (E) and (Z)-ferrocenyl oxindoles were prepared by coupling substituted oxindoles to ferrocenylcarboxyaldehyde in the presence of morpholine as a catalyst. The redox behavior of these isomers was determined by cyclic voltammetry. The effects of the oxindole derivatives on the migration of human breast cancer cells were evaluated using the wound-healing assay and the Boyden chamber cell-migration assay. The most potent Z isomers 11b (IC(50) = 0.89 microM), 12b (IC(50) = 0.49 microM) and 17b (IC(50) = 0.64 microM) could represent attractive new lead compounds for further development for cancer therapy.

Síntese de 5-nitro-isatina e 5-cloro-isatina a partir da isonitrosoacetanilida

Abstract: This article describes the preparation of 5-nitroisatin and of 5-chloroisatin from isonitrosoacetanilide in a single step, using readily available and inexpensive reagents. These reactions require around 90 minutes and may be carried out as an undergraduate experiment, providing an opportunity to discuss the electrophilic aromatic substitution mechanism, as well as spectroscopic techniques for product identification.

O uso de aparelhos de micro-ondas domésticos em aulas experimentais de química orgânica: nitração de salicilaldeído

Abstract: The use of microwave in chemistry has known benefits over conventional heating methods, e.g. reduced reaction times, chemical yield improvement and the possibility if reducing or eliminating the use of organic solvents. We describe herein a procedure for the nitration of salicylaldehyde in water using a domestic microwave oven, which can be used as an experiment in the undergraduate chemistry laboratory. The experiment involves safe and rapid preparation and identification of the position isomers by thin layer chromatography and 1H NMR, or by their melting points.

3 New Norditerpenes With An Isopimarane Skeleton From Vellozia-variabilis

Abstract: Three new γ-lactone norditerpenes with an isopimarane skeleton were isolated from roots, stem and leaf sheaths of Vellozia variabilis. X-ray diffraction analysis established the structure of one of these norditerpenes. The other two were elucidated through spectroscopic data and chemical correlation.

(2E)-N-(3,5-Dibromo-4-methoxy-phen-yl)-2-(hydroxy-imino)acetamide.

Abstract: The title compound, C9H8Br2N2O3, is planar (r.m.s. deviation = 0.030 A) with the exception of the terminal methyl group which lies out of the plane [1.219 (3) A]. The conformation about the C=N double bond [1.268 (3) A] is E. An intra­molecular N—H⋯N hydrogen bond occurs. Linear supra­molecular chains along the b axis mediated by O—H⋯O hydrogen-bonding inter­actions feature in the crystal structure. These chains are also stabilized by weak C—H⋯N contacts.

Two Monoisoprenylated Flavonoids from Vellozia graminifolia.

Abstract: A mixture of two monoisoprenylated flavonols velloquercetin 3′,4′-dimethyl ether and velloquercetin 3,3′,4′-trimethyl ether have been isolated and characterized from the hexane whole plant extract of Vellozia graminifolia . The structures were determined from spectral data, including 2D-NMR experiments.