The extract from stem bark of Stryphnodendron obovatum Benth. was chromatographed on a Sephadex ® LH-20 column, and yielded nine compounds: gallic acid (GA), p-hydroxybenzoic acid (PHB), gallocatechin (GC), epigallocatechin (EPG), 4'-O-methylgallocatechin (MGC), epigallocatechin-(4b→8)-epigallocatechin (EPEP), epigallocatechin-(4b→8)-gallocatechin (EPGC), robinetinidol-(4a→8)-gallocatechin (ROGC) and robinetinidol-(4b→8)-epigallocatechin (ROEP). Evaluation of the antioxidant capacity in vitro by the methods of DPPH free radical (IC 50 ; mg/mL) and reduction of the phosphomolybdenum complex (RAC) gave the following results, respectively: crude extract 4.52 and 0.8242; ethyl-acetate fraction 4.04 and 0.9537; aqueous fraction 5.58 and 0.9275. The crude extract and ethyl-acetate fraction were shown to possess an antioxidant capacity comparable to that of vitamin C (4.93 and 1.0). The values obtained by the DPPH free-radical method for the isolated compounds were IC 50 (μM): GA=8.89; PHB=10.12; GC=16.46; EPG=13.20; MGC=21.00; EPEP=6.89; EPGC=4.91; ROGC=7.78 and ROEP=6.20. Vitamin C and trolox showed 30.11 and 30.10, respectively. Dimers showed greater activity in scavenging free radicals, possibly related to the number of hydroxyls. However, compounds without a hydroxyl at position 5 of the A-ring (5-deoxy-proanthocyanidins) did not change the antioxidant activity of the DPPH free radical, as evaluated here for the first time. Among the monomers, there appeared to be a direct relationship in scavenging of free radicals because of the stereochemistry of the compounds. The presence of a methyl radical on the B-ring significantly reduced the scavenging of free radicals of gallocatechin. All compounds showed greater scavenging of radicals than vitamin C and trolox, and these two compounds showed no significant difference from each other.Uniterms: Stryphnodendron obovatum. Antioxidant capacity. Condensed tannins. DPPH free radical. Phosphomolybdenum complex.O extrato das cascas de Stryphnodendron obovatum submetido à cromatografia em coluna, Sephadex ® LH-20, forneceu nove substâncias: ácido gálico (GA), ácido p-hidróxibenzóico (PHB), galocatequina (GC), epigalocatequina (EPG), 4'-O-metilgalocatequina (MGC), epigalocatequina-(4b→8)-epigalocatequina (EPEP), epigalocatequina-(4b→8)-galocatequina (EPGC), robinetinidol-(4a→8)-galocatequina (ROGC) e robinetinidol-(4b→8)-epigalocatequina (ROEP). A capacidade antioxidante in vitro pelos métodos do radical livre DPPH (IC 50 ; mg/mL) e do complexo fosfomolibdênio (CAR) apresentou os seguintes resultados, respectivamente: extrato bruto 4,52 e 0,8242; fração acetato de etila 4,04 e 0,9537 e fração aquosa 5,58 e 0,9275 demonstrando possuírem capacidade antioxidante quando comparados com vitamina C 4,93 e 1,0. Os valores obtidos pelo método do radical livre DPPH com as substâncias isoladas foram: IC 50 (μM): GA=8,89; PHB=10,12; GC=16,46; EPG=13,20; MGC=21,00; EPEP=6,89; EPGC=4,91; ROGC=7,78 e ROEP=6,20 tendo sido avaliadas aqui pela primeira vez. Entre os monômeros, parece haver uma ...

Phyllanthus niruri L. has been used in folk medicine to treat hepatitis, diabetes, urinary tract disorders, and renal calculi. Here, the chemical differences among its organs and the seasonal chemical variability in the aerial parts were evaluated. The chromatographic profile and gallic acid, corilagin, and ellagic acid contents were determined by ultrahigh performance liquid chromatography with photodiode array ultraviolet (UHPLC-PDA/UV) method, which showed adequate resolution and a short analysis time. The contents of gallic acid, corilagin and ellagic acid in the leaf extract were 2.8, 6.7 and 7.9%, respectively, whilst their contents in the stem and root extracts were lower (< 0.2%). Thus, using the whole plant or aerial parts for herbal medicines can produce different biological responses. The chemical profile of the aerial parts showed only quantitative variation over 12 months. The seasonal content of gallic acid showed no correlation with monthly rainfall, but the contents of corilagin and ellagic acid were positively correlated with rainfall.