Recebido em 14/4/08; aceito em 13/11/08; publicado na web em 25/3/09 CHEMICAL AND BIOLOGICAL STUDIES OF Microgramma vacciniifolia (LANGSD. & FISCH.) COpEL (pOLypODIACEAE). Chemical studies with aerial parts of Microgramma vacciniifolia (Langsd. & Fisch.) Copel. afforded β-sitosterol, hopan-22-ol, 6-metoxiapinenin-7-O-β-D-allopyranoside and a mixture containing ethyl esters of carboxilic acids. The structures of the coumpounds were elucidated by spectroscopy and GC-MS analysis. The total phenolics contents of the crude extract and fractions were determined by Folin-Ciocalteau method. The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DppH). The AcOEt fraction showed better activity in DppH assay (9.9 ± 0.03 µg/mL), and presented also higher contents of the total phenolic (93.60 ± 1.11 µg/mg). Antimicrobial and allelopathic effects of the crude etanolic extract and fractions also were evaluated. In addition, the combination of biological activities was discussed.

The essential oils from the stem barks and leaves of Croton urucurana Baillon (Euphorbiaceae) were analyzed by GC-FID and GC-MS. 100 compounds were identified and borneol (14.7 %), bornyl acetate (5.2 %), cadina-4,10(14)-dien-1α-ol (14.7 %), sesquicineole (10.5 %) and γ-gurjunene epoxide (5.4 %) were the main components in essential oil from the steam barks. The oil from leaves was rich in sesquiterpenoids, mainly germacrene-D (15.2 %) and bicyclogermacrene (36.4 %). The in vitro cytotoxicity of the oils was evaluated against nine cancer cell lines and herbicidal effects against two seeds. The antimicrobial and antioxidant activities of the oils also were evaluated. The essential oil of stem bark was found to be more active than oil from leaves.

We investigated antioxidant capacity, phenolic content and phytotoxic effects in seven species of fruit native to Brazil: Acrocomia aculeata, Hymenaea stigonocarpa, Tamarindus indica, Byrsonima intermedia, Psidium firmum, Myrciaria cauliflora and Ficus obtusifolia. Phytotoxic effects were assessed from crude ethanol extracts and semipurified fractions. In four of the seven fruits, total phenolic content, as determined by Folin-Ciocalteu assay, was higher in the peel than in the pulp. We found that total phenolic content correlated significantly with antioxidant capacity. High-performance liquid chromatography with diode array detection revealed the presence of the flavonoids quercetin and rutin in some fruits. We also evaluated the allelopathic effects of the crude ethanol extract and semipurified fractions. In most of the essays, the ethyl acetate fractions showed the highest level of activity.

-Tree establishment in pasture areas can be inhibited, at least in part, by exotic grasses allelopathy and this can represent an important limitation by changing the patterns of both germination and seedling growth of tree species. This study aims to evaluate the allelopathic potential of Urochloa brizantha and U. decumbens on germination, growth and metabolism of Guazuma ulmifolia seedlings. We performed bioassays evaluating the effect of the crude ethanol extract and semipurified fractions (hexane fraction, ethyl acetate fraction and ethanol-water fraction) of U. brizantha and U. decumbens using completely randomized design, with four concentrations (0, 250, 500, 1,000 mg L -1) and four replications. The variables analyzed were germination percentage, mean germination time, shoot and root growth, catalase and peroxidase activity, chlorophyll content and root respiration. The results showed that both grasses have an inhibitory effect on G. ulmifolia metabolism, affecting both germination and seedlings growth and inducting metabolic defense. Thus, these results show that the grass species evaluated have the potential to restrict the re-introduction of G. ulmifolia in pasture areas due to interference competition.Keywords: Guazuma ulmifolia, interference competition, exotic grasses, direct sowing, restoration, Urochloa. RESUMO -O estabelecimento

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Essential oils from the stems and leaves of Croton doctoris were analyzed by gas chromatography and mass spectrometry, resulting in 22 identified compounds. The effects of these essential oils on the germination, root and shoot growth, total chlorophyll content, potential root respiration, peroxidase activity, catalase, superoxide dismutase, and mitotic index in lettuce and onion were determined. Antioxidant, antimicrobial, and cytotoxic activity were also investigated. The results revealed that the stem oil consisted of 15 compounds, of which caryophyllene oxide (24.5%) and E-caryophyllene (13.3%) were the major constituents. The leaf oil contained E-caryophyllene (39.6%) and α-humulene (13.2%) as major compounds. The oils inhibited the germination and growth of lettuce and onion seedlings and reduced chlorophyll content, root respiration, and cell division. They also caused oxidative stress, indicated by the increased activity of the evaluated antioxidant enzymes. These abnormal physiological processes contributed to the inhibition of plant growth. The most pronounced phytotoxic effects were observed in the stem oil. The cytotoxicity tests indicated that leaf oil was more active than stem oil, resulting from the presence of biologically active sesquiterpenes that inhibit the growth of cancer cells.

RESUMO:O objetivo desse trabalho foi avaliar a atividade alelopática dos lixiviados das raízes e folhas secas de Asemeia extraaxillaris sobre o crescimento de corda de viola Ipomoea cordifolia em casa de vegetação, para avaliação dos efeitos sobre o estresse oxidativo. Nos bioensaios foram utilizadas três concentrações (0,25 -5,00 e 10,00 g) e um controle, com quatro repetições de 10 plantas, cultivadas em solo durante 30 dias. Os lixiviados possuem ação alelopática e o maior efeito foi verificado para o pó das raizes. O efeito inibitório foi dose-dependente e o aumento do estresse oxidativo foi observado pelos níveis da catalase, peroxidase, superóxido dismutase, glutationa redutase, peroxidação lipídica e síntese de formazan. Concluiu-se que A. extraaxillaris possui substâncias capazes de afetar a emergência, o crescimento e o estresse oxidativo de I. cordifolia.Palavras chave: estresse oxidativo, lixiviação, fitoherbicida, mentol-do-campo, corda-de-viola.ABSTRACT: Allelopathic activity of leachates from Asemeia extraaxillaris (Polygalaceae) on the growth of Ipomoea cordifolia. The purpose of this article is to assess the allelopathic activity of leachates from the roots and dried leaves of Asemeia extraaxillaris on the germination and growth of corda de viola (Ipomoea cordifolia) in a greenhouse, and evaluate its effect on oxidative stress. For the bioassays, three concentrations (0.25, 5.00, and 10.00 g) and one control were used, with four replications of 10 plants, cultivated in soil for 30 days. The leachates exhibited allelopathic action, and the greatest effect was found in the root powder. The inhibitory effect was dose-dependent and the increase in oxidative stress was observed by the levels of catalase, peroxidase, superoxide dismutase, glutathione reductase, lipid peroxidation, and formazan synthesis. It was affirmed that A. extraaxillaris contains substances capable of affecting seedling emergence, growth, and oxidative stress in I. cordifolia.