The fruits of Dipteryx lacunifera, known as fava de morcego and garampara, comprise pleasant tasting kernels that contain high amounts of fatty acids (mainly oleic acid) and are commonly consumed by inhabitants of the northeast of Brazil. In the present study, the crude EtOH extract of the fruit kernels was separated into hexane-, Et 2 O-, AcOEt-, and H 2 O-soluble fractions. The Et 2 O fraction was found to exhibit the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity in vitro, and was subjected to further fractionation. Column chromatography over silica gel and Sephadex LH-20, followed by preparative HPLC-C 18 , afforded (À)-eriodictyol (1), (À)-butin (2), luteolin (3), 3',4',7trihydroxyflavone (4), butein (5), and sulfuretin (6). The antiradical activities of compounds 1, 2, 4, and 6, together with the positive controls rutin, butylated hydroxy toluene (BHT), and tert-butylhydroquinone (TBHQ), were evaluated with the DPPH assay and were found to decrease in the order rutin > 4 > 1 > 6 > 2 > TBHQ > BHT.Introduction. -Various classes of metabolites have been isolated from members of the genus Dipteryx (family Leguminosae-Papilionoideae) including coumarins, isoflavones, fatty acids, triterpenoids, and furanocassane diterpenoids [1 -7]. Kernels of the fruits of Dipteryx lacunifera Ducke, a species that is widely distributed in the northeast of Brazil, where it is popularly known as fava de morcego or garampara, are prized for their pleasant flavor, high energy content, and anti-oxidant activities [8] [9]. In previous studies, the fruits of this species have been found to contain sesquiterpenoids [1], furanocassane diterpenoids and fatty acids [1] [9], but no information is available concerning the occurrence of the polar constituents that are associated with its antiradical properties.Free radicals are known to play a key role in biological damage and are implicated in the etiology of several degenerative conditions such as rheumatoid arthritis, coronary arterial disease, diabetes, and cancer. The consumption of various plant products, including vegetables, fruits, and herbal medicines, possessing radical-scavenging activities is apparently associated with low risk for these diseases [10 -13]. In the present study, an activity-guided fractionation of an Et 2 O-soluble fraction obtained from a crude ethanolic extract of fruit kernels of D. lacunifera was conducted, and four 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging flavonoids were isolated and identified. Since the fruits are already accepted for human consumption in Brazil, the