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Nove limonóides foram isolados de Carapa guianensis e Cedrela fissilis. Entre eles, a 1,2-diidro-3β-hidroxi-7-desacetoxi-7-oxogedunina é uma substância inédita. Além disso, alguns deslocamentos químicos da xilocensina k foram corrigidos e os dados de RMN 1 H da 7-desacetilgedunina são descritos pela primeira vez na literatura. Seis dos limonóides isolados foram submetidos a ensaios com formigas Atta sexdens rubropilosa e apresentaram atividade inseticida moderada. Nine limonoids were isolated from Carapa guianensis and Cedrela fissilis. Among them, 1,2-dihydro-3β-hydroxy-7-deacetoxy-7-oxogedunin is a new compound. Moreover, the assignments of some chemical shifts of xyloccensin k have been corrected and 1 H NMR data of 7-deacetylgedunin have been assigned for the first time. These isolated limonoids were assayed on Atta sexdens rubropilosa workers showing moderate insecticidal activities.

(WHO 1997). Its treatment is still a challenge, since the only drug commercially available (benznidazole) possesses severe side effects and its activity is limited to the acute phase of the disease (De Castro 1993, Fairlamb 1999. Coura and De Castro (2002) mention that an effective chemotherapy is needed for the people who are already infected. The demonstration of parasites in chronic patients reinforces the need of finding more efficient and less toxic drugs.In the context of efforts to improve the therapy of Chagas disease, higher plants are a potential source of new drugs, with high activity and low toxicity (Phillipson & Wright 1991). Sepúlveda-Boza and Cassels (1996) mentioned a broad spectrum of chemical classes of substances showing activity against the parasite. Other promising compounds are the 2-aryl and 2-alkylquinoline alkaloids isolated from the extracts of the stem bark, root bark and leaves of Galipea longiflora (Rutaceae) (Fournet et al. 1994) and lignans from Zanthoxylum naranjillo (Rutaceae) (Bastos et al. 1999). In addition, we have been studying species of the order Rutales (Rutaceae, Meliaceae, Simaroubaceae, Burseraceae, and Cneoraceae) and several active substances have been isolated, mainly trypanocidal compounds (Mafezoli et al. 2000, Tomazela et al. 2000, Vieira et al. 2001.In this paper, we present the results of the trypanocidal activity of some extracts and fractions of Almeidea coerulea, Almeidea rubra, Conchocarpus heterophyllus, and Galipea carinata (from Rutaceae family), as well as Trichilia ramalhoi (from the family Meliaceae). Also, the results of the in vitro trypomastigote bioassay with flavone (1) and 7-methoxyflavone (2), the major compounds of one active fraction, are described. MATERIALS AND METHODSPlant material -All screened plants were collected in Southeastern Brazil, and identified by Dr José R Pirani from the Department of Botany, University of São Paulo, Brazil. The voucher herbarium specimens were deposited at the Herbarium of that Department (Table I).Preparation of crude extracts -Selected parts of the plants (leaves, stems, and/or branches) were dried carefully by forced air at 40°C and reduced to powder, followed by extraction three times with hexane by maceration at room temperature for 72 h. After the evaporation of the solvent under reduced pressure, crude hexane extracts were obtained. This process was repeated with methanol. The hexane and methanol extracts so obtained were assayed against T. cruzi.Fractionation of crude extracts -Methanol extracts of T. ramalhoi were fractionated through liquid-liquid partition with hexane-methanol-water, dichloromethanemethanol-water, ethyl acetate-methanol-water, and butanol-methanol-water. The crude extracts of A. coerulea, A. rubra, C. heterophyllus, G. carinata, and the hexane extract of the leaves of T. ramalhoi were submitted to vacuum liquid chromatography over silica gel using a gradient hexane, dichloromethane, ethyl acetate, and methanol, to yield the corresponding fractions, which were subsequently tested ...