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Resumo -O objetivo deste trabalho foi avaliar a assimilação metabólica de nitrogênio em plântulas de seringueira cultivadas na presença de nitrato ou de amônio, por meio da quantificação da atividade das enzimas redutase do nitrato (RN), glutamina sintetase (GS), glutamato sintase (GOGAT) e glutamato desidrogenase (GDH). Os seguintes tratamentos foram avaliados: fontes de N -controle, sem aplicação de N; amônio a 8 mmol L -1 ; e nitrato a 8 mmol L -1 -e tempos de exposição -0 e 27 dias -, em arranjo fatorial 3x2, no delineamento inteiramente casualizado, com quatro repetições. A forma amoniacal promoveu maior assimilação metabólica de N, o que resultou em maior acúmulo de aminoácidos. A assimilação, tanto da forma nítrica quanto da amoniacal, aconteceu principalmente via GS/GOGAT; parte do N nítrico é assimilado nas raízes, com pequena participação da GDH, e parte é translocada para outros órgãos. O N amoniacal é totalmente assimilado nas raízes, com significativa participação da GDH. Nas folhas, a GS participa tanto da assimilação primária como da reassimilação do amônio fotorrespirado, independentemente da fonte nitrogenada, enquanto a enzima GDH tem papel secundário, independentemente da fonte ou do tempo de exposição. A atividade da RN in vitro é detectada somente em raízes e caules.Termos para indexação: Hevea brasiliensis, amônio, atividade enzimática, fonte de nitrogênio, metabolismo, nitrato. Metabolic assimilation of nitrogen in rubber tree seedlings grown with nitrate or ammoniumAbstract -The objective of this work was to evaluate metabolic assimilation of nitrogen in rubber tree seedlings grown with nitrate or ammonium, by quantifying the activity of the enzymes nitrogen reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH). The following treatments were evaluated: nitrogen sources -control, without N application; 8 mmol L -1 ammonium; and 8 mmol L -1 nitrate -, and exposure times -0 and 27 days -, in a 3x2 factorial arrangement, in a completely randomized block design with four replicates. The ammoniacal form favored higher N metabolic assimilation, which lead to a higher aminoacid accumulation. Both nitrate and ammonium assimilations occurred mainly by GS/GOGAT route; part of the nitric nitrogen is assimilated in the roots, with little GDH participation, and the other part is translocated to other organs. Ammonium nitrogen is totally assimilated in roots, with a significant participation of GDH. In the leaves, GS participates in the primary assimilation, as well as in the photorespiratory ammonium re-assimilation, irrespective of the N source, while GDH has a secondary role, independently of the source or of the exposure time. In vitro RN activity is detected only in the roots and stems.

This study investigated the antioxidant and anti-inflammatory effects from the inner bark of Mimosa tenuiflora. The hydroethanol extract (HEE) and its hexane (HXF), chloroform (CLF), ethyl acetate (EAF) and hydromethanol (HMF) fractions were prepared and submitted to phytochemical screening and antioxidant activity. In vivo anti-inflammatory effect was investigated by using 12-Otetradecanoylphorbol 13-acetate (TPA)-induced edema and myeloperoxidase (MPO) activity in mice ears. Phytochemical prospection of HEE revealed the presence of flavonoids, tannins, xantones, triterpenes, esteroids and phenols. Higher total phenol content was found in EAF and higher percentages of inhibition of 2,2-diphenyl-1-picrylhydrazyl free DPPH radical were found for HEE, EAF or HMF. Lipid peroxidation (LP) induced by 2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH) was greatly inhibited by HEE or EAF, while inhibition of FeSO 4-induced LP was higher for HMF. The coadministration of HEE (1 or 3 mg/ear) decreased edema (p<0.001) and MPO activity (p<0.05). All fractions reduced mice ear edema at the same extent, however, while EAF and HMF reduced MPO activity in mice ear at both 1 and 3 mg/ear (p<0.001 and p<0.05 respectively), CLF only at 3 mg/ear (p<0.05) and HXF did not affect this parameter. Taken together, these results demonstrate that inner bark of M. tenuifolia possesses antioxidant and anti-inflammatory effects.