Alaíde Braga de Oliveira

PHARMACOLOGICAL EVALUATION OF THE ANTI-INFLAMMATORY ACTIVITY OF A CITRUS BIOFLAVONOID, HESPERIDIN AND THE ISOFLAVONOIDS, DUARTIN AND CLAUSSEQUINONE IN RATS AND MICE

Abstract— Pretreatment of rats with hesperidin (50 and 100 mg kg−1, s.c.) reduced the paw oedema induced by carrageenan by 47 and 63%, respectively, within 5 h. The effect was equivalent to that produced by indomethacin (10 mg kg−1, p.o.), although unrelated to the administered dose, particularly at high doses. At 100 mg kg−1 hesperidin decreased the rat paw oedema induced by dextran by 33%, without influencing the histamine‐induced paw oedema. Hesperidin also inhibited pleurisy induced by carrageenan, reducing the volume of exudate and the number of migrating leucocytes by 48 and 34%, respectively, of control values. Equal doses of duartin and claussequinone were ineffective in all the above tests. Pretreatment of mice with hesperidin (100 mg kg−1, s.c.) reduced acetic acid‐induced abdominal constriction by 50%, but did not affect the tail flick response. Hyperthermia induced by yeast in rats was slightly reduced by hesperidin. No lesions of the gastric mucosae were detected in rats pretreated with hesperidin. The results indicate that hesperidin obtained from citrus cultures may present a potential therapeutical use as a mild antiinflammatory agent, being also useful as a precursor of new flavonoids endowed with such activity.

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).

Plant-Derived Antimalarial Agents: New Leads and Efficient Phytomedicines. Part II. Non-Alkaloidal Natural Products

Malaria is still the most destructive and dangerous parasitic infection in many tropical and subtropical countries. The burden of this disease is getting worse, mainly due to the increasing resistance of Plasmodium falciparum against the widely available antimalarial drugs. There is an urgent need for new, more affordable and accessible antimalarial agents possessing original modes of action. Natural products have played a dominant role in the discovery of leads for the development of drugs to treat human diseases, and this fact anticipates that new antimalarial leads may certainly emerge from tropical plant sources. This present review covers most of the recently-published non-alkaloidal natural compounds from plants with antiplasmodial and antimalarial properties, belonging to the classes of terpenes, limonoids, flavonoids, chromones, xanthones, anthraquinones, miscellaneous and related compounds, besides the majority of papers describing antiplasmodial crude extracts published in the last five years not reviewed before. In addition, some perspectives and remarks on the development of new drugs and phytomedicines for malaria are succinctly discussed.

Trypanocidal activity and redox potential of heterocyclic- and 2-hydroxy-naphthoquinones

Abstract With the aim of understanding the influence of redox potentials on the trypanocidal activity, a series of quinones were tested in vitro with trypomastigotes of Trypanosoma cruzi and their first cathodic potentials (Epcl) measured by cyclic voltammetry. All quinones with Epcl > −0.72V were active, while most of those with Epcl

Occurrence, Biological Activities and Synthesis of Kaurane Diterpenes and their Glycosides

This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed.

Plant-derived antimalarial agents: new leads and efficient phythomedicines. Part I. Alkaloids.

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.

Identification of Some Chemical Components of the Essential Oil from Molasses Grass (Melinis minutiflora Beauv.) and their Activity Against Cattle-Tick (Boophilus microplus)

The essential oil of molasses grass (Melinis minutiflora Beauv.) has shown virtually 100% lethal effect on larvae of the cattle-tick (Boophilus microplus) within 10 min exposure. GC/MS analysis of the essential oil led to the identification of six major components: propionic acid, butyric acid, phenylethyl alcohol, hexanal, 1,8-cineole and 9 -E-eicosene. Two of those components (1,8-cineole and n-hexanal) have also shown individually 100% lethal effect on cattle-tick larvae within 10 min. The presence of 2,6-di-t-butyl-4-methylphenol was assigned to a contaminant from commercially supplied diethyl ether used for the essential oil extraction.

Trypanocidal Sesquiterpenes from Lychnophora Species

The bioguided fractionation of the crude extracts of Lychnophora passerina (Mart. ex DC) Gardn., L. pinaster Mart. and L. trichocarpha Spreng. led to the isolation of four compounds active against the trypomastigote forms of Trypanosoma cruzi: the sesquiterpene lactones goyazensolide (1), eremantholide C (2), and lychnopholide (3) and a new caryophyllene derivative, which was named lychnophoic acid (4).

Azafluorenones and azaanthraquinone from Guatteria dielsiana

Abstract Trunkwood of Guatteria dielsiana afforded eight alkaloids and one triterpene. Three of the alkaloidal constituents are oxoaporphines: liriodenine, O -methylmoschatoline and isomoschatoline; four are 1-azafluorenones: onychine, the only previously known representative of this group, and three novel compounds of this rare type, 6-methoxyonychine, dielsine (1-aza-4-methyl-2-oxo-1,2-dihydrofluorenone) and dielsinol (1-aza-4-hydroxymethyl-2 oxo-1,2-dihydrofluorenone). The last alkaloid is dielsiquinone (1-aza-3-methoxy-4-methyl-2-oxo-1,2-dihydro-9,10-anthracenedione), the second representative of a new class of quinones of which cleistopholine was the only one previously known. The triterpene is polycarpol whose presence is of chemotaxonomic significance since this metabolite seems to be exclusive to the Annonaceae.

Growth inhibitory effect of naphthofuran and naphthofuranquinone derivatives on Trypanosoma cruzi epimastigotes

Abstract Synthetic and natural naphthofuranquinones were tested in vitro against three Trypanosoma cruzi strains with different drug susceptibility to nifurtimox and benznidazole in vivo . Four compounds exhibited high trypanocidal activity. No difference in drug susceptibility was found among the strains, therefore showing no correlation between the in vitro activity of those compounds and the in vivo results with the classic drugs.