Avaliação da atividade antiedematogênica, antimicrobiana e mutagênica das sementes de Amburana cearensis (A. C. Smith) (Imburana-de-cheiro) / Assessment of the antiedematogenic, antimicrobial and mutagenic activity of Amburana cearensis seeds (A.C. Smith) (Imburana-de-cheiro)

Foram avaliados os efeitos antiinflamatório, antibacteriano e mutagênico do extrato aquoso das sementes de Amburana cearensis. A atividade antiinflamatória foi avaliada em modelo de edema de pata induzido por carragenina, utilizando o extrato em concentrações de 10 % e 20 % nos grupos experimentais; AAS 10 mg/kg (v.o) no grupo padrão e água destilada no grupo controle. A atividade antimicrobiana foi determinada através do método de diluição em Agar, utilizando concentrações de extrato de 10 %, 7,5 %, 5 %, 2,5 % e 1 % em cepas de Sthaphylococcus aureus ATCC 27853, Escherichia coli ATCC 25922 e Pseudomonas aeruginosas ATCC 25923) e a atividade mutagênica foi determinada pelo teste de Allium cepa, utilizando extrato em concentrações de 0,02 mg/mL, 0,1 mg/mL e 0,5 mg/mL. O extrato aquoso das sementes de Amburana cearensis nas concentrações de 10 % e 20 % apresentou efeito antiedematogênico, estatisticamente significativo a partir de duas horas após administração do flogógeno, e tal efeito persistiu até 24 horas após a indução da resposta inflamatória. Quanto à atividade antibacteriana, o extrato não apresentou ação contra as cepas bacterianas de Sthaphylococcus aureus, Escherichia coli e Pseudomonas aeruginosas nas concentrações testadas. A análise dos resultados do teste de Allium cepa evidenciou ação tóxica (em concentração de 0,5 mg/mL) e mutagênica (micronúcleo 0,1 mg/mL e aberrações cromossômicas 0,1 mg/mL e 0,5 mg/mL) do extrato de Amburana cearensis em células meristemáticas de Allium cepa. Tais resultados sugerem potencial aplicação terapêutica no tratamento da inflamação. Contudo, também demonstram a necessidade de estudar para comprovar a segurança na utilização dessa espécie.

The anti-inflammatory, antibacterial and mutagenic effects of the aqueous extract of Amburana cearensis seeds were evaluated. The anti-inflammatory activity was evaluated by a paw edema model induced by carrageenan, using the extract at 10 % and 20 % concentrations in the experimental groups: AAS 10 mg/kg (orally administrated) in the standard group and distilled water in the control group. The antimicrobial activity was determined by the agar dilution method, using extract concentrations of 10 %, 7.5 %, 5 %, 2.5 % and 1% in strains of Staphylococcus aureus ATCC 27853, Escherichia coli ATCC 25922 and Pseudomonas aeruginosas ATCC 25923), and the mutagenic activity was determined by the Allium cepa test using extract concentrations of 0,02 mg/mL, 0,1 mg/mL and 0,5 mg/mL. The aqueous extract of Amburana cearensis seeds at 10 % and 20 % concentrations had an statistically significant antiedematogenic effect two hours after administering the flogogen, and this effect persisted for up to 24 hours after inducing the inflammatory response. Regarding the antibacterial activity, the extract showed no action against the bacterial strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosas at the concentrations tested. The results of the Allium cepa test showed the toxic (at a concentration of 0,5 mg/mL) and mutagenicity (0.1 mg/mL micronucleus and 0.1 mg/mL and 0.5 mg/mL chromosomal aberrations) actions of the Amburana cearensis extract on meristematic cells of Allium cepa. These results suggest potential therapeutic applications to treat inflammations. However, they also show the need for further studies to demonstrate the safe use of this species.

Ontogenetic modulation of branch size, shape, and biomechanics produces diversity across habitats in the Bursera simaruba clade of tropical trees.

Organismal size and shape inseparably interact with tissue biomechanical properties. It is therefore essential to understand how size, shape, and biomechanics interact in ontogeny to produce morphological diversity. We estimated within species branch length-diameter allometries and reconstructed the rates of ontogenetic change along the stem in mechanical properties across the simaruba clade in the tropical tree genus Bursera, measuring 376 segments from 97 branches in nine species in neotropical dry to rain forest. In general, species with stiffer materials had longer, thinner branches, which became stiffer more quickly in ontogeny than their counterparts with more flexible materials. We found a trend from short stature and flexible tissues to tall statures and stiff tissues across an environmental gradient of increasing water availability, likely reflecting a water storage-mechanical support tradeoff. Ontogenetic variation in size, shape, and mechanics results in diversity of habits, for example, rapid length extension, sluggish diameter expansion, and flexible tissues results in a liana, as in Bursera instabilis. Even species of similar habit exhibited notable changes in tissue mechanical properties with increasing size, illustrating the inseparable relationship between organismal proportions and their tissue mechanics in the ontogeny and evolution of morphological diversity.

Diversification in species complexes: tests of species origin and delimitation in the Bursera simaruba clade of tropical trees (Burseraceae).

Molecular phylogenies are invaluable for testing morphology-based species delimitation in species complexes, as well as for examining hypotheses regarding the origination of species in these groups. Using five nucleotide markers, we reconstructed the phylogeny of the Bursera simaruba species complex of neotropical trees to test the notion that four "satellite" species originated from populations of the most widely distributed member of the genus, B. simaruba, which the satellites strongly resemble. In addition to molecular phylogenetic reconstruction, we tested species delimitation of B. simaruba and the satellites using multivariate analyses of morphological and ecological characters. The analyses evaluated the taxonomic value of these traditional characters and pinpointed those in need of further study, such as the expression of pubescence. Phylogenetic data rejected the origin of three satellite species from their purported ancestor, B. simaruba, and we ascribe their morphological similarity to convergence or parallelism. The fourth satellite species likely represents one end of a spectrum of inflorescence length variation within B. simaruba and is conspecific. Despite its marked morphological variability, we recovered B. simaruba as a single valid species, which implies that it maintains genetic cohesion among distant populations throughout its vast range.

Timing the origin and expansion of the Mexican tropical dry forest.

Macroevolution examines the temporal patterns of biological diversity in deep time. When combined with biogeography, it can provide unique information about the historical changes in the distribution of communities and biomes. Here I document temporal and spatial changes of diversity in the genus Bursera and relate them to the origin and expansion of the tropical dry forests of Mexico. Bursera is very old, highly adapted to warm dry conditions, and a dominant member of the Mexican tropical dry forest. These characteristics make it a useful indicator of the history of this vegetation. I used a time-calibrated phylogeny to estimate Bursera's diversification rate at different times over the last 60 million years. I also reconstructed the geographic center and time of origin of all species and nodes from information on current distributions. Results show that between 30 and 20 million years ago, Bursera began a relatively rapid diversification. This suggests that conditions were favorable for its radiation and thus, very probably for the establishment of the dry forest as well. The oldest lineages diverged mostly in Western Mexico, whereas the more recent lineages diverged in the south-central part of the country. This suggests that the tropical dry forest probably first established in the west and then expanded south and east. The timing of the radiations in these areas corresponds to that suggested for formations of the mountainous systems in Western and Central Mexico, which have been previously recognized as critical for the persistence of the Mexican dry forest.

Evolution of Mexican Bursera (Burseraceae) inferred from ITS, ETS, and 5S nuclear ribosomal DNA sequences.

I reconstructed a phylogeny of 66 species and varieties of Bursera and 9 outgroup species using sequences of the internal transcribed spacer region (ITS), the 5S non-transcribed region (5S-NTS), and the external transcribed region (ETS) of nuclear ribosomal DNA. This study extends a previously proposed parsimony-based phylogenetic study that used the ITS sequences of 57 Bursera species and five outgroups. Parsimony and maximum likelihood methods were used to infer the phylogeny in this new study. Analyses of the combined data sets largely confirmed the phylogenetic relationships proposed by the previous molecular study but generated a considerably more robust topology. The new phylogenies corroborate the monophyly of the genus, and its division into the two monophyletic subgenera or sections, Bursera and Bullockia. The current analyses also identify four main groups of species in section Bursera, and two in section Bullockia, confirming some of the previously proposed groups based on fruit, flower, and leaf morphology. One previously problematic species B. sarcopoda, which has sometimes been placed in Commiphora, is shown to belong in Bursera. Another controversial species, Commiphora leptophloeos, which was thought to belong to Bursera, falls within Commiphora.