In the literature there are a considerable number of chemical and biochemical tests for evaluation of in vitro antioxidant activities of pure compounds or fractions and organic extracts. These tests are important tools for screening of synthetic and natural bioactive compound as well as they can be employed in food chemistry. This work is a critical review of the main methods employed for in vitro antioxidant determination.

The chloroform partition of methanol extract of leaves of Caesalpinia pyramidalis was submitted to different chromatographic procedures which afforded besides agathisflavone and taxifolin, the minor biflavones loniflavone, amentoflavone, 5'- hydroxyamentoflavone and podocarpusflavone A. The structures of the compounds were established on the basis of NMR and MS data analysis. Besides, the content of biflavones of different specimens of C. pyramidalis, which are collected in different habitats of the Brazilian semi-arid region, was determinated by LC-APCI-MS analysis. These analysis demonstrated that only the specimens harvested in Bahia state showed collectively the presence of agathisflavone, amentoflavone, sequoiaflavone and podocarpusflavone A.

O reestudo do extrato clorofórmico das folhas de Caesalpinia pyramidalis (Caesalpinioidea, Fabaceae) forneceu, além do novo biflavonóide denominado caesalflavona, podocarpusflavona A, agathisflavona, apigenina, kaempferol, sitosterol e lupeol. Por outro lado, a partir do extrato clorofórmico do caule foram obtidos 4, 4'-diidroxi-2'-metoxi-chalcona, (-)-siringaresinol e galato de metila. Não foram encontrados biflavonóides nesta parte da planta. Até o presente, C. pyramidalis é a primeira espécie do gênero que contém biflavonóides. As estruturas das substâncias foram estabelecidas através da análise dos seus dados espectrométricos utilizando-se técnicas de EM, IV, UV, RMN 1D e 2D.

The chloroform extract of the leaves of Caesalpinia pyramidalis (Caesalpinioidea, Fabaceae) yielded the new biflavonoid named caesalflavone, as well as podocarpusflavone A, agathisflavone, apigenin and kaempferol. The chloroform extract of the trunk wood gave 4,4'-dihydroxy-2'-methoxychalcone, (-)-syringaresinol, and methyl gallate. Biflavonoids were not found in trunk wood. Until now, C. pyramidalis is the first species in the genus to present biflavonoids. The structural elucidation of the isolated compounds and their derivatives were based on MS, IR, UV, 1D and 2D NMR spectral analyses.