Leaf-cutter ants cultivate and feed on the mutualistic fungus, Leucoagaricus gongylophorus, which is threatened by parasitic fungi of the genus Escovopsis. The mechanism of Escovopsis parasitism is poorly understood. Here, we assessed the nature of the antagonism of different Escovopsis species against its host. We also evaluated the potential antagonism of Escovopsioides, a recently described fungal genus from the attine ant environment whose role in the colonies of these insects is unknown. We performed dual-culture assays to assess the interactions between L. gongylophorus and both fungi. We also evaluated the antifungal activity of compounds secreted by the latter on L. gongylophorus growth using crude extracts of Escovopsis spp. and Escovopsioides nivea obtained either in (1) absence or (2) presence of the mutualistic fungus. The physical interaction between these fungi and the mutualistic fungus was examined under scanning electron microscopy (SEM). Escovopsis spp. and E. nivea negatively affected the growth of L. gongylophorus, which was also significantly inhibited by both types of crude extract. These results indicate that Escovopsis spp. and E. nivea produce antifungal metabolites against the mutualistic fungus. SEM showed that Escovopsis spp. and E. nivea maintained physical contact with the mutualistic fungus, though no specialised structures related to mycoparasitism were observed. These results showed that Escovopsis is a destructive mycoparasite that needs physical contact for the death of the mutualistic fungus to occur. Also, our findings suggest that E. nivea is an antagonist of the ant fungal cultivar.

This study assesses the storage temperature effect on the anthocyanins of pasteurized and unpasteurized açaí pulp. The data was obtained using a pasteurized and lyophilized pulp (PLP) to evaluate the temperature effect (0, 25, and 40 °C). Part of non-pasteurized frozen pulp (NPP) was pasteurized (NPP-P) at 90 °C for 30 seconds; both pulps were stored at 40 °C. The anthocyanin content reduction in the drink was evaluated from the half-life time (t1/2), activation energy (Ea), temperature quotient (Q10), and the reaction rate constant (k). The t1/2 of the PLP anthocyanins stored at 40 °C was 1.8 times less than that stored at 25 °C and 15 times less than that stored at 0 °C; therefore, the higher temperatures decreased the stability of anthocyanins. The pasteurization increased the t1/2 by 6.6 times (10.14 hours for NPP and 67.28 hours for NPP-P). The anthocyanin degradation on NPP-P followed a first order kinetic, while NPP followed a second order kinetic; thus it can be said that the pasteurization process can improve the preservation of anthocyanins in the pulp.

Recebido em 3/7/10; aceito em 29/9/10; publicado na web em 8/11/10 COUMARINS AND ALKALOIDS FROM Rauia resinosa (RUTACEAE). The genus Rauia, that is poorly chemically studied, belongs to the Rutaceae family. This family has been known to contain a large variety of secondary metabolites. Our phytochemical investigation of the stem and leaves of Rauia resinosa has led to the identification of the structurally related coumarins: murralongin (1), murrangatin (2), munomicrolin (3), murrangatin diacetate (4), umbelliferone (5), rauianin (6) and one novel coumarin: 3-ethylrauianin (7); the alkaloids: N-methyl-4-methoxy-2-quinolone (8), mirtopsine (9), dictamine (10), g-fagarine (11), skimmianine (12), Z-dimethylrhoifolinate (13), zantodioline (14), zantobungeanine (15), veprissine (16), one novel alkaloid 7-hydroxy-8-methoxy-N-methylflindersine (17) and 8-hydroxy-N-methylflindersine (18) that is described as a natural product for the first time, and a mixture of steroids: as sitosterol and stigmasterol.Keywords: Rauia resinosa; coumarins; alkaloids. INTRODUÇÃOO gênero Rauia, taxonomicamente posicionado na família Rutaceae, subfamília Rutoideae, tribo Galipeae (anteriormente Cusparieae) e sub-tribo Galipeinae (antes Cuspariinae), 1,2 ainda é pouco conhecido com relação ao seu potencial químico. De Rauia resinosa Nees & Mart foi isolada a cumarina conhecida como rauianina. 3A família Rutaceae é constituída de aproximadamente 150 gê-neros e 1600 espécies de árvores e arbustos distribuídas nas regiões tropicais e temperadas do globo terrestre. 4 No Brasil estão citados 33 gêneros e aproximadamente 192 espécies.5 Esta família é conhecida por apresentar uma grande diversidade de metabólitos secundários, destacando-se os alcaloides, especialmente os derivados do ácido antranílico, cumarinas, lignanas, flavonoides, terpenos e limonoides com largo espectro de atividades biológicas. 4,6,7 As cumarinas são substâncias amplamente encontradas em plantas, entretanto, espécies pertencentes às famílias Rutaceae e Umbelliferae representam as fontes mais ricas destes metabólitos, onde ocorrem com grande diversidade estrutural. 8,9 Os alcaloides relatados na ordem Rutales são derivados do áci-do antranílico, triptofano, fenilalanina, histidina, ácido nicotínico, ornitina ou lisina e, em alguns casos, podem ser derivados de dois precursores. 4 Os alcaloides derivados do ácido antranílico têm distribuição restrita fora da família Rutaceae, atuando como marcador quimiotaxonômico desta. 10 PARTE EXPERIMENTAL Procedimentos geraisOs espectros de ressonância magnética nuclear de hidrogênio e carbono-13 (RMN 1 H e 13 C) em uma e duas dimensões foram obtidos nos aparelhos ARX 200 MHz e DRX 400 MHz da Bruker. Os solventes utilizados foram CDCl 3 e CD 3 OD e TMS como padrão interno.As análises cromatográficas em camada fina foram realizadas em cromatoplacas de sílica gel F 254 sobre placa de alumínio Merck, de 0,2 mm de espessura, empregando-se como revelador solução de vanilina/ ácido sulfúrico. As separações cromatográficas em colunas foram rea...