Mara S.P. Arruda

Potencial alelopático de Myrcia guianensis

The use of fire and mowing as weed methods have proved inefficient. Although more efficient, synthetic chemical herbicides are usually related to environmental problems. Thus, the search for natural herbicides has become a priority matter. Based on these facts, research was conducted on Myrcia guianensis (pedra-ume-caa) including the isolation and identification of chemical substances with allelophatic activity. The allelophatic effects of extracts, fractions, essential oils, and isolated chemical substances (gallic acid and protocatechuic acid) on germination and radicle and hypocotyl growth of weed species Mimosa pudica (malicia) and Senna obtusifolia (mata-pasto) were analyzed. Extracts and fractions were analyzed at a concentration of 1%, essential oils at 15, 30, 45, 60 ppm and the isolated chemical substances at 15, 30, 45, 60 ppm. Malicia showed more sensitivity to the allelophatic effects of extracts and fractions. The essential oil inhibited the germination of M. pudica but stimulated that of S. obtusifolia. The allelophatic effects of the chemical substances were concentration dependent and the strongest activity was observed at 60 ppm.

A dimeric ArC2 compound from Peperomia pellucida.

Pellucidin A, a novel dimeric ArC2 compound, together with dill-apiol have been isolated from the aerial parts of Peperomia pellucida. The structure of pellucidin A was established by 1D and 2D NMR spectroscopy (1H-1H COSY; 1H-13C COSY; DEPT; NOESY and double irradiation) and other spectroscopic techniques. The biogenesis of pellucidin A is also briefly discussed.

Avaliação do efeito antifúngico do óleo resina e do óleo essencial de copaíba (Copaifera multijuga Hayne)

Copaifera multijuga Hayne oil in natura and its fractions were evaluated as to their fungitoxic activities against five filamentous fungus species belonging to the genus Aspergillus and three yeast species of the genus Candida. Oleoresin and essential oil concentrations ranging from 0.08 mg mL-1 to 1.6 mg mL-1 were used for qualitative and quantitative analyses. The samples were placed onto 5mm-diameter paper discs distributed on Sabourauds medium in Petri dishes inoculated with spores of the microorganisms and incubated at 28oC for 10 days. A solution containing 1.6 mg mL-1 miconazole nitrate was used as positive control. Qualitative results showed that the oleoresin presented good activity, while a fraction of the essential oil was highly effective against Candida parapsilosis IOC-2882, Aspergillus flavus IOC-3874 and A tamarii IOC-187 with 16.0±1.4 mm, 19.5±2.1 mm and 12.5±3.5 mm inhibition halos, respectively. The quantitative evaluation showed that 0.3 mg mL-1 oleoresin inhibited the growth of Aspergillus flavus and Candida parapsilosis, while 0.08 mg mL-1 of the essential oil fraction reached this same activity.

Chemical constituents and allelopathic and antioxidant activities of Alchorneopsis floribunda Müll. Arg. (Euphorbiaceae)

Chemical investigation of extracts from the stems and leaves of Alchorneopsis floribunda Müll. Arg., collected in the Amazon region, was performed. The main isolated compounds were triterpenes (α-amyrin, β-amyrin, lupeol, betulin, betulinic acid, uvaol, erythrodiol and oleanolic acid) and phenolic acid derivatives from 4-hydroxybenzoic acid (gallic and protocatechuic acids and isocorilagin). In the germination assays, high inhibitory allelopathic effects of the extracts and isocorilagin were observed and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of isocorilagin was higher than those of the standards used (Trolox and butylated hydroxyanisole). This is the first chemical study of the genus Alchorneopsis (Euphorbiaceae).

Identification and antioxidant activity of several flavonoids of Inga edulis leaves

Um extrato metanol-agua das folhas de Inga edulis foi fracionado para identificar os compostos polifenolicos. Os compostos identificados foram o acido galico, a catequina, a epicatequina, a miricetina-3-ramnopiranosideo, a quercetina-3-glucopiranosideo e a quercetina-3-ramnopiranosideo. A capacidade antioxidante do extrato e dos polifenois puros foi medida pelo teste ORAC e comparada com o teor em fenolicos totais (TP). O extrato bruto seco apresentou valores de ORAC (11.16 mmol TE per g) e TP (496.5 mg GAE per g) muito altos. Os compostos identificados foram responsaveis, respectivamente, por 9.53 % e 12.10 % dos valores ORAC e de TP do extrato de folhas de Inga edulis.

Limonoids of the phragmalin type from Swietenia macrophylla and their chemotaxonomic significance.

Species of Swietenia elaborate limonoid chemistry along only one route, which leads to the mexicanolide type in most species and the phragmalin type in S. mahogani. A hexane extract from leaves of S. macrophylla afforded six new phragmalins with a 8,9,30-ortho-ester unit, namely, 6-O-acetylswietephragmin E (1), 3beta-O-destigloyl-3beta-O-benzoyl-6-O-acetylswietephragmin E (2), 12alpha-acetoxyswietephragmin C (3), 3beta-O-destigloyl-3beta-O-benzoyl-12alpha-acetoxyswietephragmin C (4), 12alpha-acetoxyswietephragmin D (5), and 3beta-O-destigloyl-3beta-O-benzoyl-12alpha-acetoxyswietephragmin D (6). This appears to be the first record of phragamalins from S. macrophylla, and this study shows the potential of tricyclic [3.3.1(2,10).1(1,4)]-decane limonoids as taxonomically useful chemical markers in the Meliaceae.

Chemistry of Zanthoxylum rhoifolium: A new secofuroquinoline alkaloid

Abstract Six coumarins, four furoquinoline alkaloids, one glycosylflavonoid, two triterpenes, and one steroid have been characterized from stems, leaves and fruit of Zanthoxylum rhoifolium Lam. var. petiolulatum Engler ( Fagara rhoifolium ), of which one furoquinoline alkaloid is a new compound. The composition is very different from other reported studies of Z. rhoifolium . The structures of the compounds isolated were determined by spectroscopic methods.

Substâncias químicas com atividades alelopáticas presentes nas folhas de Parkia pendula (Leguminosae)

Os objetivos deste trabalho foram isolar, identificar e caracterizar a atividade alelopatica de substâncias quimicas produzidas por Parkia pendula. Os efeitos alelopaticos foram avaliados sobre a germinacao de sementes e o desenvolvimento da radicula das plantas daninhas malicia (Mimosa pudica) e mata-pasto (Senna obtusifolia). O processo de isolamento das substâncias envolveu a extracao com solvente em ordem crescente de polaridade, e a elucidacao estrutural foi realizada via Ressonância Magnetica Nuclear, espectro de COSY e de HETCOR. Os bioensaios foram desenvolvidos em condicoes controladas de 25 oC de temperatura e fotoperiodo de 12 (germinacao) e 24 horas (desenvolvimento da radicula). Foram isolados e identificados nas folhas da P. pendula os seguintes aleloquimicos: acido 3,4,5-trimetoxibenzoico (S1), acido 3,4-dimetoxibenzoico (S2) e o Blumenol A (S3). Comparativamente, S1 e S2 apresentaram maior atividade alelopatica. Os efeitos promovidos sobre o desenvolvimento da radicula foram de maior magnitude do que aqueles verificados sobre a germinacao das sementes. As substâncias isoladas mostraram baixo potencial inibitorio da germinacao das sementes, especialmente as sementes de mata-pasto. Os efeitos alelopaticos inibitorios estiveram positivamente associados a concentracao das substâncias, embora em alguns casos esses efeitos nao tenham correspondido as diferencas estatisticas.

Dihydroflavonols from the leaves of Derris urucu (Leguminosae): structural elucidation and DPPH radical-scavenging activity

Derris urucu e uma planta da Amazonia com propriedades inseticida e ictiotoxica. Estudos com esta especie reportam a presenca de flavonoides, principalmente rotenoides, bem como de estilbenos. A partir do extrato etanolico das folhas de Derris urucu (Leguminosae), tres novos diidroflavonoides, denominados urucuol A (1), B (2) e C (3) e o diidroflavonol isotirumalina (4), foram isolados e identificados. As estruturas destes compostos foram elucidadas por uma extensiva analise espectroscopica de RMN uni e bidimensional, UV, IV e dados de EM, alem de comparacao com dados da literatura. Os compostos isolados (1-4) foram avaliados quanto ao seu potencial sequestrador do radical DPPH• e apresentaram baixo poder antioxidante quando comparados ao antioxidante comercial trans-resveratrol.

Two flavans from Brosimum acutifolium

Abstract Two new flavans were isolated from a dichloromethane extract of the bark of Brosimum acutifolium and identified as 4′-hydroxy-7,8-(2″,2″-dimethylpyran)flavan and 4′-hydroxy-7,8-(3″-hydroxy-2″,2″-dimethylpyran)flavan. Structures were elucidated by spectral data.