الفهرس 
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Abstract
Crataegus sinaica from South Sinai at Saint Catherine protectorate in Egypt recorded to be used in the Egyptian folklore medicine for treatment of hypertension, arrhythmia, and congestive heart failure. The aim of this research was to synthesize highly stable silver nanoparticles by green synthesis technology using the infusions of Crataegus sinaica leaves and fruits and to study the biological activity of the extracts and the prepared silver nanoparticles. The investigated extracts of Crataegus sinaica fruits and leaves extracts that are used as a reducing and capping agent showed greater capability for synthesizing silver nanoparticles at optimum temperature conditions. The synthesized silver nano particles were confirmed by color changes, spectroscopic analysis, transmission electron microscope and zeta potential analysis. Accordingly, the estimated phenolics, tannins, flavonoids, alkaloids and carbohydrates content in the Crataegus sinaica leaves and fruits extracts greatly confirmed their capability to act as bio-reductants of silver ions to nano silver. The prepared nano silver using Crataegus sinaica leaves and fruits extracts expressed wide spectrum of the activity against most of the tested pathogenic microorganisms that were higher than the extracts themselves. The allelopathic bioassay of the aqueous extracts of fruits and leaves of Crataegus sinaica and silver nano solutions prepared using these extracts illustrated by studying their phytotoxic effects on seed germination and seedling growth of the targeted Echinocholae crusgalli and Oryza sativa grains were evaluated. The aqueous extracts from leaves and fruits of Crataegus sinaica expressed inhibition potential at both lower and higher concentrations on the germination of Echinochola crusgalli seeds while the prepared nano silver solution from both leaves and fruits extracts expressed complete inhibition to germination of Echinochola crusgalli seeds. On the other hand, the germination of Oryza sativa grains was 100% in the control, the seeds treated with nano silver solutions prepared from leaves and fruits extracts and the seeds treated with 10% and 20% of the aqueous extracts of Crataegus sinaica. In conclusion, this approach seems to be one of the best models to be used in the therapeutic management of infectious diseases and controlling of the growth of harmful weeds in some potentially important crops.