Resprouting from roots in four Brazilian tree species

Previous studies pointed out that species richness and high density values within the Leguminosae in Brazilian forest fragments affected by fire could be due, at least partially, to the high incidence of root sprouting in this family. However, there are few Studies of the factors that induce root sprouting in woody plants after disturbance. We investigated the bud formation on root cuttings, and considered a man-made disturbance that isolates the root from the shoot apical dominance of three Leguminosae (Bauhinia forficata Link., Centrolobium tomentosum Guill. ex Benth, and Inga laurina (Sw.) Willd) and one Rutaceae (Esenbeckia febrifuga (St. Hit.) Juss. ex Mart.). All these species resprout frequently after fire. We also attempted to induce bud formation on root systems by removing the main trunk, girdling or sectioning the shallow lateral roots from forest tree species Esenbeckia febrifuga and Hymenaea courbaril L. We identified the origin of shoot primordia and their early development by fixing the samples in Karnovsky solution, dehydrating in ethyl alcohol series and embedding in plastic resin. Serial sections were cut on a rotary microtome and stained with toluidine blue O. Permanent slides were mounted in synthetic resin. We observed different modes of bud origin on root cuttings: close to the vascular cambium (C. tomentosum), from the callus (B. forficata and E febrifuga) and from the phloematic parenchyma proliferation (L laurina). Fragments of B. forficala root bark were also capable of forming reparative buds from healing phellogen formed in callus in the bark's inner side. In the attempt of bud induction on root systems, Hymenaea courbaril did not respond to any of the induction tests, probably because of plant age. However, Esenbeckia febrifuga roots formed suckers when the main trunk was removed or their roots were sectioned and isolated from the original plant. We experimentally demonstrated the ability of four tree species to resprout from roots after disturbance. Our results suggest that the release of apical dominance enables root resprouting in the studied species. Rev. Biol. Trop. 57 (3): 789-800. Epub 2009 September 30.

Antimalarial chemotherapy with natural products and chemically defined molecules

In the present work we have described the in vivo antimalarial actrivity of six different plants. Two of them (Verninia brasiliana and Eupatorium squalidum) were tested in a randomic approach among 273 crude extracts from plants; four (Acanhospermum australe, Esenbeckia febrifuga, Lisianthus specious and Tachia guianensis) were selected after screening 22 crude extracts from different medicinal and some of them showed antimalarial activity in vitro. Some aspects of recent research with natural products aiming to produce drugs are discussed.

Chlorophyll fluorescence of tropical tree species in a semi-deciduous forest gap

The characterization of different ecological groups in a forest formation/succession is unclear. To better define the different successional classes, we have to consider ecophysiological aspects, such as the capacity to use or dissipate the light energy available. The main objective of this work was to assess the chlorophyll fluorescence emission of tropical tree species growing in a gap of a semi-deciduous forest. Three species of different ecological groups were selected: Croton floribundus Spreng. (pioneer, P), Astronium graveolens Jacq. (early secondary, Si), and Esenbeckia febrifuga A. Juss. (late secondary, St). The potential (Fv/Fm) and effective (deltaF/Fm') quantum efficiency of photosystem II, apparent electron transport rate (ETR), non-photochemical (qN) and photochemical (qP) quenching of fluorescence were evaluated, using a modulated fluorometer, between 7:30 and 11:00 h. Values of Fv/Fm remained constant in St, decreasing in P and Si after 9:30 h, indicating the occurrence of photoinhibition. Concerning the measurements taken under light conditions (deltaF/Fm', ETR, qP and qN), P and Si showed better photochemical performance, i.e., values of deltaF/Fm', ETR and qP were higher than St when light intensity was increased. Values of qN indicated that P and Si had an increasing tendency of dissipating the excess of energy absorbed by the leaf, whereas the opposite was found for St. The principal component analysis (PCA), considering all evaluated parameters, showed a clear distinction between St, P and Si, with P and Si being closer. The PCA results suggest that chlorophyll fluorescence may be a potential tool to differentiate tree species from distinct successional groups.

Aurapten, a coumarin with growth inhibition against Leishmania major promastigotes

Several natural compounds have been identified for the treatment of leishmaniasis. Among them are some alkaloids, chalcones, lactones, tetralones, and saponins. The new compound reported here, 7-geranyloxycoumarin, called aurapten, belongs to the chemical class of the coumarins and has a molecular weight of 298.37. The compund was extracted from the Rutaceae species Esenbeckia febrifuga and was purified from a hexane extract starting from 407.7 g of dried leaves and followed by four silica gel chromatographic fractionation steps using different solvents as the mobile phase. The resulting compound (47 mg) of shows significant growth inhibition with an LD50 of 30 µM against the tropical parasite Leishmania major, which causes severe clinical manifestations in humans and is endemic in the tropical and subtropical regions. In the present study, we investigated the atomic structure of aurapten in order to determine the existence of common structural motifs that might be related to other coumarins and potentially to other identified inhibitors of Leishmania growth and viability. This compound has a comparable inhibitory activity of other isolated molecules. The aurapten is a planar molecule constituted of an aromatic system with electron delocalization. A hydrophobic side chain consisting of ten carbon atoms with two double bonds and negative density has been identified and may be relevant for further compound synthesis.

Chlorophyll fluorescence of tropical tree species in a semi-deciduous forest gap

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Composição florística e fitossociológica de três fragmentos de floresta ribeirinha em Ajapi, Rio Claro - SP

A vegetação ribeirinha é conhecida como o conjunto de formações que se encontram associadas aos corpos d’água, ocorrendo ao longo dos cursos d’água e no entorno de nascentes, formando um mosaico vegetacional. É de vital importância na proteção de mananciais, controlando a chegada de nutrientes, sedimentos e a erosão de ribanceiras, atua na estabilidade térmica e abastece o lençol freático a partir da contenção de águas pluviais, além de exercer um papel fundamental como corredores ecológicos de fluxo gênico animal e vegetal. No Brasil, há legislação que protege tais áreas, entretanto, estas vem sofrendo sistemática degradação por desmatamento, despejo de esgotos domésticos e industriais, canalização e desvio de cursos d’água. O estudo presente teve como objetivo caracterizar a florística e a estrutura fitossociológica de três fragmentos do ambiente ribeirinho localizados na Fazenda Água Branca, em Ajapi, Rio Claro - SP. Através de parcelas de 10x10m, foram amostrados todos os indivíduos com PAP ≥ 10cm. Foram estabelecidas 16 parcelas na vegetação ribeirinha com influência fluvial sazonal ao longo do Ribeirão Claro, tratadas no trabalho como floresta ciliar. Foram estabelecidas 14 parcelas distribuídas em dois fragmentos de vegetação ribeirinha com influência fluvial permanente, tratadas ao longo do trabalho como floresta paludosa. Na mata ciliar, foram amostrados 316 indivíduos, pertencentes a 32 famílias, distribuídos em 74 espécies. As espécies mais importantes foram: Syzygium cuminii, Esenbeckia febrifuga e Croton urucurana. As famílias com maior riqueza foram: Myrtaceae, Fabaceae, Euphorbiaceae e Meliaceae. O índice de diversidade (H’) encontrado foi 3,62; valor esperado para Florestas Estacionais Semideciduais. Na mata paludosa, foram amostrados 469 indivíduos, pertencentes a 34 famílias, distribuídos em 60 espécies... (Resumo completo, clicar acesso eletrônico abaixo)

Genetic diversity of Metrodorea nigra (Rutaceae) from a small forest remnant in Brazil assessed with microsatellite markers

Metrodorea nigra (Rutaceae) is an endemic Brazilian tree of great ecological importance, frequently found in the submontane regions of ombrophilous dense and semideciduous forests. This tree is useful for reforesting degraded areas and the wood can be employed in construction. We developed 12 microsatellite markers from a genomic library enriched for GA/CA repeats, for this species. Polymorphisms were assessed in 40 trees of a highly fragmented population found in Cravinhos, State of Sao Paulo, in southeastern Brazil. Among the 12 loci, 8 were polymorphic and only one had fixed alleles in this population. The number of alleles per locus and expected heterozygosity ranged from 2 to 11 and from 0.190 to 0.889, respectively. These results revealed moderate levels of genetic variation in M. nigra population when compared to other tropical species. Additionally, transferability of the 12 primers was tested in seven other Brazilian Rutaceae tree species (endemics: M. stipularis, Galipea jasminiflora, Esenbeckia leiocarpa and non-endemics: E. febrifuga, E. grandiflora, Balfourodendron riedelianum, Zanthoxylum riedelianum). Transferability ranged among species, but at least 8 loci (similar to 67%) amplified in M. stipularis, demonstrating a high potential for transferring microsatellite markers between species of the same genus in the Rutaceae family.

Caracterização farmacognóstica da droga e do extrato fluido de mentrasto: Ageratum conyzoides L.

A especie vegetal Argentum conyzoides L., empregada popularmente como antidiarreica, antiespasmódica, carminativa, febrifuga, antirreumática teve sua propriedade anti inflamatória comprovada cientificamente, foi estudada morfológica e anatomicamente com vistas a sua caracterização farmacognostica . O extrato fluido da referida planta foi analisado por cromatografia em camada delgada, através de diversos sistemas cromatográficas, com vistas a fornecer subsídios ao controle de qualidade deste insumo farmacêutico.