Maria Inês Salgueiro Lima

Atividade alelopática de extratos aquosos de Aristolochia esperanzae O. Kuntze na germinação e no crescimento de Lactuca sativa L. e Raphanus sativus L.

This work analyzed the effects of aqueous extractsof Aristolochia esperanzae organs in the germination and initial growth of lettuce and radish. All the extracts were prepared using 100g of plant fresh material + 300mL of distilled water to produce the extract 100% concentrated. This extract was diluted with distilled water to produce a final concentrations of 75, 50 and 25%. The germination was evaluated by tests using the extracts of leaf, stem, root, fruit and flower, with concentration of 100, 75, 50, and 25%. In the seedlings growth, the extracts of leaf, stem, and root were used in the concentration of 100 and 50%. In the germination tests, four replicates of 30 seeds were distributed in Petri dishes with two filter paper moistened with 5mL of the extracts, dried during 12 hours and moistened again with 4,5mL of distilled water. In the first test, the rate and germination percentage were evaluated. In the growth test, the seeds were previously germinated (2-4mm radicle length) and transferred for plastic boxes containing the filter paper or coconut fiber, moistened with the extracts. The shoot height, radicle length, dry mass and the presence of abnormalities in the seedlings were evaluated. Both tests were maintained at constant temperature (27oC). The results showed that the leaf extracts affected strongly the germination percentage and all the extract, in different concentrations, delayed the germination of lettuce and radish seeds. In the growth tests could be verified that the stem and root extracts caused abnormality in the seedlings. The seedlings grown in filter paper presented bigger growth inhibition in relation to seedlings from coconut fiber. The extract concentration was the main responsible for the promotion or inhibition caused on lettuce and radish seedlings growth.

Efeito alelopático de Andira humilis Mart. ex Benth na germinação e no crescimento de Lactuca sativa L. e Raphanus sativus L.

Neste trabalho, objetivou-se avaliar o efeito alelopatico de caules e folhas de Andira humilis na germinacao de sementes e no crescimento de plântulas de rabanete e alface. Para os experimentos de germinacao foram preparados extratos aquosos de caules e folhas de A. humilis nas concentracoes de 0, 4, 8, 12 e 16% (p/v). Foram realizadas quatro replicas de trinta sementes de alface ou de rabanete, distribuidas em placas de Petri forradas com papel-filtro umedecido com 5mL dos extratos, mantidas a 27 oC e na ausencia de luz. As contagens das sementes germinadas foram realizadas a cada 12h, calculando-se a percentagem e a velocidade de germinacao. Extratos de caules e folhas reduziram significativamente a velocidade e a percentagem de germinacao, em relacao ao grupo controle. Os experimentos de crescimento foram realizados com quatro replicas de oito sementes germinadas de alface ou de rabanete, a 27 oC, na ausencia de luz e em papel-filtro como substrato, sendo avaliadas as concentracoes 0, 4 e 12% (p/v). Plântulas de alface e rabanete sofreram inibicao significativa em seus comprimentos, pelos extratos de folhas. Extratos de caules a 4 e 12% (p/v) nao causaram inibicao do crescimento em rabanete. A interferencia dos extratos na germinacao e no crescimento em alface e rabanete foi desassociada de qualquer efeito do potencial osmotico e do pH, indicando, portanto, atividade alelopatica.

Orchidaceae na região central de São Paulo, Brasil

Abstract This study reports the floristic survey of Orchidaceae occurring in 125 forest fragments distributed among 23counties of the central region of Sao Paulo state, Brazil. In this region, the family is characterized by 219species distributed in 96 genera. Individuals collected in the vegetative state were maintained in a greenhouseuntil flowering. The majority of species (64%) are epiphytes, while 35% are terrestrial, 14.6% are rupicolous,two (0.9%) are hemi-epiphytes and one is mycoheterotrophic (0.4%). Acianthera (13 spp.), Habenaria andGomesa (12 spp.), and Epidendrum (11 spp.) are the most representative genera. Of the unidentified species,four are possibly new to science: Anathallis sp., Baskervilla sp., Pelexia sp., Triphora sp. Furthermore, a newcombination for the genus Gomesa R.Br. is presented. The central portion of Sao Paulo state is an ecotonebetween Brazilian Savanna and Atlantic Forest with a high number of species from both formations. Manyspecies (44.7%) are rare in the study area and are threatened due to anthropogenic disturbance and indiscriminatecollecting of orchids.Key words: Savanna, ecotone, Atlantic Forest, floristic survey.

Networks of epiphytic orchids and host trees in Brazilian gallery forests

Species interactions have been recently depicted as networks, in which each species is connected to one or more other species in binary interaction matrices. Forty networks of epiphytic orchid and host tree species were assessed in Brazilian gallery forests. The nestedness of the networks was estimated with the NODF index and the significance was tested with null models. The phylogenetic structure of the network was also assessed, by searching for phylogenetic signals in the number of interactions and in the similarity of interacting species. In total, 105 orchid speciesand132hosttreespeciesweresampled.Anestedpatterninallorchid-hosttreenetworkswasfound.However, phylogenetic signals were not observed. The results support that the host specificity of orchids is small and most of the interactionsoccuramonggeneralistorchidsandgeneralisthosttrees.Whiletheconceptofspecies-specificitycanthus be rejected, the extreme alternative - that interacting orchids and host trees are not a random subset of the regional species pool - can be dismissed as well. However, factors other than phylogenetic history may structure interaction networks of epiphytic orchids and host trees.

Potencial alelopático do extrato foliar de Annona glabra L. (Annonaceae)

A. glabra is a wetland species, occurring in dense populations. This behavior may indicate strong competition with other species or the existence of an allelopathic process involved in this distribution. In this study, we aim to: a) evaluate the allelopathic potential of extracts produced by A. glabra leaves on germination and seedling growth of other species and on wheat coleoptile growth and b) verify the presence of substance groups on the extracts and fractions studied. The qualitative test detected triterpenes, tannins and flavonoids. A Liquid:liquid partition chromatography of aqueous extract was done, using hexane and ethyl acetate. The activities of the fractions obtained were tested on germination and initial growth of Lactuca sativa, Echinochloa crus-galli, Euphorbia heterophylla and Ipomoea grandifolia. The ethyl acetate fraction reduced L. sativa germination percentage and E. crus-galli mean germination time and affected the initial growth of all species. This fraction was purified by chromatographic column which resulted in five fractions (A, B, C, D and E). Four concentrations (1000; 158; 79; 39.5 ppm) were prepared for each one. Effects caused by fractions were evaluated by wheat coleoptile tests. Fraction A stimulated elongation at all concentrations except 1000 ppm. Fraction B was inhibitory at all concentrations except for the smaller one. C was inhibitory only at the higher concentration and E did not cause a significant effect.

Isolation of Arginase Inhibitors from the Bioactivity-Guided Fractionation of Byrsonima coccolobifolia Leaves and Stems

Byrsonima coccolobifolia leaf and stem extracts were studied in the search for possible leishmanicidal compounds using arginase (ARG) from Leishmania amazonensis as a molecular target. Flavonoids 1b, 1e-1g, 2a, 2b, and 2d-2f showed significant inhibitory activity, with IC50 values ranging from 0.9 to 4.8 μM. The kinetics of the most active compounds were determined. Flavonoids 1e, 1f, 2a, 2b, and 2e were characterized as noncompetitive inhibitors of ARG with dissociation constants (Ki) ranging from 0.24 to 3.8 μM, demonstrating strong affinity. Structure-activity relationship studies revealed some similarities in the structural features of flavonoids related to ARG activity.

Allelopathic effects of Ipomoea cairica (L.) Sweet on crop weeds

Identification of species with allelopathic potential has been a target of researches aiming to use them to control crop weeds. Ipomoea cairica is considered a weed with allelopathic potential, which has already been reported. The goal of this study was to evaluate the allelopathic properties of leaf extracts from Ipomoea cairica on the germination and early development of four of the worst crop weeds in Brazil: Bidens pilosa L., Echinochloa crus-galli (L.) Beauv., Euphorbia heterophylla L. and Ipomoea grandifolia (Dammer) O´Donel. We tested the effects of leaf extracts, in four concentrations, on the germination and early development of these species. The extracts negatively affected the germination, early development and the morphology of all target species, and the phytotoxic effect was higher as the concentration of the extracts increased. The influence of the I. cairica extracts on germination, in addition to their effects on seedling development, made them more effective.

Leishmanicidal galloylquinic acids are noncompetitive inhibitors of arginase

Leishmanicidal galloylquinic acids were isolated from the ethyl acetate extract of Byrsonima coccolobifolia. These phenols and gallic acid showed to be a new class of potent noncompetitive inhibitors of arginase ARG (Ki ranging from 0.10 to 0.68 µmol L -1 ) from Leishmania amazonensis. Quinic acid did not exhibit significant inhibition of ARG, indicating that galloyl moiety has important features that allows the enzyme-inhibitor interactions. The significant inhibitory activity of gallic acid on ARG can be a clue to understand the immune response previously observed on L. donovani, since ARG activity is associated with the decrease of the levels of NO in Leishmania infection.

Plantae, aquatic, amphibian and marginal species, Massaguaçu River estuary, Caraguatatuba, São Paulo, Brazil

Estuaries are the buffer zones between river and ocean. Because they are under strong tidal influence, their flora must be able to cope with salinity and flooding stress. In the present study we combined results from two surveys we performed in the Massaguacu River Estuary (23°37’20” S, 54°21’25” W), with the objective of providing a full inventory of its aquatic, amphibian, and marginal flora. We reported 102 species among 77 genera and 47 families, including six Pteridophyta species.

Evaluation of flavonols and derivatives as human cathepsin B inhibitor

Cathepsin B (catB) is a cysteine protease involved in tumour progression and represents a potential therapeutic target in cancer. Among the 15 evaluated extracts from cerrado biome, Myrcia lingua Berg. (Myrtaceae) extract demonstrated to be a source of compounds with potential to inhibit catB. Using bioactivity-guided fractionation, we have found flavonols as inhibitors and also some other derivatives were obtained. From the evaluated compounds, myricetin (5) and quercetin (6) showed the most promising results with IC50 of 4.9 and 8.2 μM, respectively, and mode of inhibition as uncompetitive on catB. The results demonstrated polyhydroxylated flavonols as promising inhibitors of catB.