RESUMO
Ethanolic extracts of 15 selected Egyptian plants belonging to 11 families were assessed in vitro as potential antioxidants using DPPH [1,1-diphenyl-2-picrylhydrazyl] free radical scavenging method. The highest activities were obtained from the extracts of Pelargonium graveolens L., Ceratonia siliqua L., Eucalyptus globulus Labill. and Psidium guajava L. The antioxidant activity of these extracts was evaluated in vivo by measurement of different parameters such as alanine aminotransferase, aspartate aminotransferase, gamma glutamyl transpeptidase, superoxide dismutase, malondialdehyde, reduced glutathione and glutathione peroxidase in serum and I or liver of carbon tetrachloride intoxicated rats. Furthermore, the total polyphenol content of these plants was determined using Folin-Ciocalteau colorimetric method. Bioassay guided fractionation of the active ethanolic extract of Ceratonia siliqua [EC[50] =8.89 [micro]g/ml] proved that the ethyl acetate fraction was the most active. This was further purified via polyamide, cellulose and sephadex LH-20 column chromatography. Antioxidant compounds were isolated and identified using UV, 'H-NMR and MS spectroscopic methods. The compounds were characterized as: acacetin-7-O-[beta]-D-glucopyranoside, quercetin-3-O-beta-D-xylopyranoside and gallic acid