الفهرس 
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Abstract
The biologically active compoundsisolated from plants are known to be efficient as antibacterial. The total phenol, flavonoid, antioxidants andantibacterial activities of the petroleum ether ethyl acetate and ethanol extracts of Opuntia ficus-indicaseeds and peels were tested. Antibacterial effects of crude extracts were performed using modified Kirby-Bauer disc diffusion technique to determine the zone of inhibition. The extracts were tested for the antibacterial activities against Gram-positive bacteria (B. Subtilis) and Gram-negative bacteria (Serratia marcescens).This plant could be developed into affordable and safe standardized herbal products and may serve as a source of new molecules for broad-spectrum antimicrobial agents. Polysaccharide Opuntia ficus peel (POFP) reaching a maximum of 13 g/L was isolated from Opuntia ficus by ethanol precipitation. The crude (POFP) was purified by chromatography on DEAE-cellulose and sephadex G-200, affording a polysaccharide active fraction (POFP) with a molecular weight of 137 kDa. (POFP)was investigated by a combination of chemical and chromatographic methods including FTIR, HPLC, periodate oxidation and methylation. Data obtained indicated that (POFP)was composed of mannose, arabinose, glucose and glucuronic acid in a molar ratio of 3.6:2.7:2.1:1.0, respectively. The main backbone consists of mannose units linked with (16)-glycosidic bonds and arabinose units linked with (15)-glycosidic bonds. There is a side chain consisting of mannose units linked with (16)-glycosidic bonds at C3, when all glucose and most of glucuronic acid are found in the side chain. The in vitro antioxidant assay showed that (POFP)possesses DPPH radical-scavenging activity, with an EC50 value of 180 lg/mL. Silver nanoparticles were synthesized using a green chemistry method. Stable silver nanoparticles in a colloidal aqueous solution were prepared successfully by the chemical reaction of silver nitrate (AgNO3) and Opuntia ficus indicaaqueous extract, used as both, reducing and stabilizing agent. Nanoparticle size, morphology and optical properties were analyzed by using transmission electron microscopy (TEM) and UV-Vis spectroscopy, respectively. TEM images revealed a nanoparticle average size of 23 nm. An absorption band centered around 398 nm was observed, this absorption corresponds to the surface plasmon resonance (SPR) of the silver nanoparticles.