ABSTRACT
Syzygium jambos (L.) Alston, Myrtaceae, é empregado na medicina popular como digestivo e antiinflamatório. A triagem fitoquímica da droga pulverizada (folhas) indicou a presença de flavonóides, taninos e óleo volátil. O extrato hidroetanólico a 70 por cento das folhas de S. jambos foi preparado por percolação e liofilizado. O conteúdo de taninos das folhas e do extrato foi calculado, respectivamente, em 21,9 por cento e 43,3 por cento. O teor de flavonóides foi de 0,6 por cento (folhas) e 1,2 por cento (extrato). A administração oral prévia do extrato (400 mg/kg) a ratos Wistar reduziu significativamente as lesões gástricas induzidas por etanol acidificado. No modelo de úlcera subcrônica, com indução de lesão gástrica utilizando ácido acético a 30 por cento, o tratamento com o extrato (400 mg/kg) não apresentou resultado significativo. A atividade antioxidante do extrato foi avaliada através dos modelos de lipoperoxidação e de medida de capacidade seqüestrante de radicais DPPH. Os valores obtidos de Q1/2 (MDA) e CE50 (DPPH) foram, respectivamente, 0,17 μg/mL e 5,68 μg/mL.
Syzygium jambos (L.) Alston, Myrtaceae, is commonly employed in folk medicine as digestive and anti-inflammatory. Phytochemical screening of the powdered dried leaves indicates the presence of flavonoids, tannins and essential oil. Hydroethanol extracts (70 percent) were prepared by percolation and freeze-drying. The tannin content of dried leaves and extract was, respectively, 21.9 percent and 43.3 percent. The flavonoid content was 0.6 percent (dried leaves) and 1.2 percent (extract). Previous oral administration of S. jambos leaves extract (400 mg/kg) to rats reduced significantly gastric injury induced by HCl/ethanol. At the subcronic ulcer model by induction with 30 percent acetic acid the results were not significant. In vitro antioxidant activity of S. jambos extract was evaluated by malondialdehyde (MDA) and DPPH free radical method. The Q1/2 for MDA assay was 0.17 μg/mL and the EC50 for DPPH assay was 5.68 μg/mL.
ABSTRACT
Oxidative stress has been implicated in many pathological conditions such as cancer, aging inflammation and cell death. The Brazilian flora is particularly rich in medicinal plants employed for many purposes. Among them the Piperaceae family and specially the "pariparobas" are widely used in the treatment of liver diseases. In vitro antioxidant activity of Pothomorphe umbellata L. Miq. was evaluated and compared with that of Piper regnellii, another plant from the Piperaceae family commonly used as it were P. umbellata. A purified fraction of the ethanolic extract of P. umbellata, containing 4-nerolidylcatechol was also assayed for antioxidant activity and compared with that of alpha-tocopherol. Rat brain homogenates were incubated with increasing aliquots of crude extracts of different parts of the plants or 4-nerolidylcatechol/alpha-tocopherol for 1 h at 37 degrees Celsius. Both malondialdehyde (MDA) and chemiluminescence (CL) were assayed to evaluate brain tissue autoxidation. The Q1/2 for MDA assay for root, stem and leaves were 4.4, 19.3 and 38.5 mug/mL for P. umbellata and 26.0,64.4 and 13.3 mug/mL for P regnellii, respectively. Calculated MDA and CL Q1/2 values for 4-nerolidylcatechol and alpha-tocopherol were O.75 and O.68 muM for 4-nerolidylcatechol and 14.4 and 1O.9 muM for alpha-tocopherol, respectively. These results indicate high antioxidant activity of P. umbellata root extract as compared to that of vitamin E, which was attributed to the presence of 4-nerolidylcatecho1.