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Biomedical subjects

A B de Oliveira

Publications and source records attributed to A B de Oliveira.

17 recordsLinked to original sources
PubMed2001

HPLC quantitation of kaurane diterpenes in Xylopia species.

Xylopia frutescens is a tree native to the Brazilian Amazon whose seeds are rich in kaurenoic acid, a diterpene that showed in vitro activity against Trypanosoma cruzi. Aiming to find out alternative sources for kaurenoic acid, the content of some kaurane diterpenes was evaluated in X. aromatica and X. brasiliensis, species occurring in the Cerrado area of Minas Gerais, and also in X. frutescens. A reversed phase HPLC isocratic method was developed and validated to perform the assays. Kaurenoic acid was found to be the most abundant diterpene within the analyzed species, with a 3.16+/-0.97% content in the seeds of X. frutescens, which also presented the highest amount of xylopic acid (1.09+/-0.33%). The highest concentration of 16-alpha-hydroxykauranoic acid (1.96+/-1.58%) was found in the stems of X. aromatica.

Chromatography, High Pressure Liquid↗
PubMed2000

Screening the Brazilian flora for antihypertensive plant species for in vitro angiotensin-I-converting enzyme inhibiting activity.

The evaluation of several antihypertensive activity of Brazilian plant species was performed using in vitro inhibition of the angiotensin I-converting enzyme (ACE). Nineteen species belonging to 13 families were investigated. Plants were selected based on their use as diuretics and on a chemosystematic consideration. Extracts of the following species presented the highest ACE inhibition rate, at concentrations of 0.33 mg/ml: Ouratea semiserrata (Mart. & Nees) Engl. stems (68%), Cuphea cartagenesis (Jacq.) Macbride leaves (50%) and Mansoa hirsuta DC. leaves (54%). Some hypotheses about the nature of the compounds that may be responsible for the activity of these species are discussed in the paper.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Screening Brazilian plant species for in vitro inhibition of 5-lipoxygenase.

Plants from the Brazilian flora were evaluated for the inhibition of 5-lipoxygenase. The species were selected based on their traditional use and on a chemosystematic approach. In total, 19 species belonging to 13 families have been investigated. Hedychium coronarium J. Koenig (Zingiberaceae), Xylopia frutescens Aubl. (Annonaceae) and Hymenaea courbaril L. (Leguminosae) presented a high 5-lipoxygenase inhibitory activity. Some hypothesis about the nature of the active compounds are discussed, based on reports of the chemical constitution of these species or other species from the same botanical family.

Enzyme Inhibitors↗
PubMed1999

Trypanosomicidal kaurane diterpenes from Wedelia paludosa.

The diterpenes ent-kaur-16-en-19-oic acid, ent-kaur-9(11),16(17)-dien-19-oic acid and 3 alpha-angeloiloxy-ent-kaur-16-en-19-oic acid were identified as trypanosomicidal compounds of the ethanolic extract from the aerial parts of Wedelia paludosa D.C. (Asteraceae), showing activity up to the lowest dose of 0.68 mg/mL in the in vitro assay against trypomastigotes of T. cruzi, the causative agent of Chagas' disease (American trypanosomiasis). The other isolates, friedelan-3 beta-ol, ent-kaur-16 alpha-ol-19-oic acid, beta-amyrin acetate and (22-E)-stigmasta-5,22-dien-3 beta-ol, were inactive. This is the first report on the trypanosomicidal activity of ent-kaur-9(11),16(17)-dien-19-oic acid and 3 alpha-angeloiloxy-ent-kaur-16-en-19-oic acids; this effect was already known for ent-kaur-16-en-19-oic acid.

Animals↗
PubMed1991

Quaternary ammonium salt derivatives of allylphenols with peripheral analgesic effect.

Ammonium salt derivatives of natural allylphenols were synthesized with the purpose of obtaining potential peripheral analgesics. These drugs, by virtue of their physicochemical properties, would not be able to cross the blood brain barrier. Their inability to enter into the central nervous system (CNS) should prevent several adverse effects observed with classical opiate analgesics (Ferreira et al., 1984). Eugenol (1) O-methyleugenol (5) and safrole (9) were submitted to nitration, reduction and permethylation, leading to the ammonium salts 4, 8 and 12. Another strategy applied to eugenol (1), consisting in its conversion to a glycidic ether (13), opening the epoxide ring with secondary amines and methylation, led to the ammonium salts 16 and 17. All these ammonium salts showed significant peripheral analgesic action, in modified version of the Randall-Sellito test (Ferreira et al., 1978), at non-lethal doses. The ammonium salt 8 showed an activity comparable to that of methylnalorphinium, the prototype of an ideal peripheral analgesic (Ferreira et al., 1984).

Analgesics↗
PubMed1983

Psychopharmacological effects of the essential oil fraction and of the hydrolate obtained from the seeds of Licaria puchury-major.

An essential oil fraction obtained from powdered seeds of Licaria puchury-major contained 51.3% of safrol, 3.3% of eugenol and 2.9% of methyleugenol, among other substances. Fifty to 800 mg/kg of this fraction reduced motor activity and anesthetized mice; it also protected the animals against transcorneal electroshock. A hydrolate obtained from the powder, contained 0.2 mg of essential oil fraction per ml: 0.1 and 0.2 ml/10 g of this hydrolate reduced motor activity and potentiated barbiturate sleeping time of mice; 2.5-10 ml/kg given to rats produced a drop in body temperature. The hydrolate, however, did not anesthetize and did not protect mice against convulsions induced by electrical shock. These amounts of the hydrolate corresponded to dosing the animals with 2-4 mg/kg of the essential oil (or 1-2 mg/kg of safrol), doses which were inactive per se. This suggested that the pharmacological activity of the hydrolate was not due to its essential oil content. Corroborating this possibility the hydrosoluble portion of the hydrolate mimicked all of its effects: reduced motor activity, potentiated barbiturate sleeping time of mice and decreased body temperature of rats. The hydrosoluble material, as the hydrolate, was also incapable of anesthetizing and protecting mice against electroshock induced convulsions.

Animals↗
PubMedDate not supplied

Screening in vitro of natural products against blood forms of Trypanosoma cruzi.

Transmission of Chagas disease by blood transfusion is a major health problem in Central and South America. The annual incidence of transfusion-transmitted Chagas disease in Brazil is about 20,000 cases. Crystal violet is the only trypanosomicidal agent available at present, but there are some restrictions on its use. In a search for possible new chemoprophylactic agents, several natural products of different structural types were tested in vitro against infective blood trypomastigotes of Trypanosoma cruzi. Four compounds had high activity at a concentration of 5 x 10(-4) M: the diarylpropanoids (3R)-claussequinone, (R)-4-methoxydalbergione and (S)-4,4'-dimethoxy-dalbergione, and 15-deoxygoyazensolide, a sesquiterpenelactone. Haemoculture and serology of mice inoculated with infected blood treated with these active compounds were negative after 3 and 6 months. The benzoquinone moiety seemed to be important for this activity since lapachol and related naphthoquinones are known to be trypanosomicidal. 15-Deoxygoyazensolide has previously been recognized as a schistosomicide.

Animals↗
PubMedDate not supplied

[Molluscacide activity of a mixture of 6-n-alkyl salicylic acids (anacardic acid) and 2 of its complexes with copper (II) and lead (II)].

The molluscicide activity of hexanic extract from Anacardium occidentale L. (cashew) nut shell, of copper (II) complex, of lead (II) complex and anacardic acid has been compared in the laboratory in an attempt to obtain better stability than anacardic acid. This was obtained from the hexanic extract of the cashew nut shell by precipitation with lead (II) hydroxide or cupric sulfate plus sodium hydroxide or (II) cupric hydroxide followed by treatment of lead (II) complex with a diluted solution of sulfuric acid. Ten products of the mixture obtained were tested on adults snails of Biomphalaria glabrata at 1 to 10 ppm. The most active products were copper (II) complex, obtained by cupric sulfate plus sodium hydroxide, and anacardic acid (sodium hydroxide) which presented activity at 4 ppm. The anacardic acid's lead content was above the limits accepted by the United States standards.

Animals↗
PubMedDate not supplied

Screening of Asteraceae (Compositae) plant extracts for larvicidal activity against Aedes fluviatilis (Diptera:Culicidae).

Ethanol extracts of 83 plants species belonging to the Asteraceae (Compositae) family, collected in the State of Minas Gerais, Brazil, were tested for larvicidal activity against the mosquito Aedes fluviatilis--Diptera: Culicidae). The extract from Tagetes minuta was the most active with a LC90 of 1.5 mg/l and LC50 of 1.0 mg/l. This plant has been the object of several studies by other groups and its active components have already been identified as thiophene derivatives, a class of compounds present in many Asteraceae species. The extract of Eclipta paniculata was also significantly active, with a LC90 of 17.2 mg/l and LC50 of 3.3 mg/l and no previous studies on its larvicidal activity or chemical composition could be found in the literature. Extracts of Achryrocline satureoides, Gnaphalium spicatum, Senecio brasiliensis, Trixis vauthieri, Tagetes patula and Vernonia ammophila were less active, killing more than 50% of the larvae only at the higher dose tested (100 mg/l).

Aedes↗