Aging in leaves is characterized by a decrease in chlorophyll content and an accompanying loss of protein and ribonucleic acid. It is well known that these symptoms of senescence occur at an accelerated rate in excised mature leaves and in leaf discs floated on water. In recent years it has been established that several chemical substances retard the senescence of leaves. Among the compounds wh...

Antibacterial activity of the aerial extracts from Xanthium brasilicum prepared in methanol, diethyl ether, petroleum benzene and an equal mixture of the three solvents were studied against bacterial laboratory standards and clinical isolates using the disk diffusion method. The best antibacterial results were obtained when methanol or the solvent mixture was used. The crude extract with the hi...