Barakat M ALRashdi¹, Mousa O. Germoush¹, Sayydah Suryya Sani², Iqra Ayub², Waqas Bashir², Bilal Hussain², Mahrukh Mazhar², Shahid Ali², Zartasha Zahid², Sana Ayesha² and Azhar Rafique^2*

Green synthesis of nanoparticles is a latest and foremost technique to replace antibiotics against resistant strains of bacteria in forthcoming era. Nano particles-based nanomedicine is the future of pharmaceutical industries. This study was designed to evaluate the antibacterial activity of green synthesis-based silver nanoparticles against an infection in rats. Salvia hispanica (S. hispanica) plant was used to reduce the silver nitrate (AgNO₃) into silver nanoparticles (AgNPs). Reduction of silver nitrate into silver nanoparticles confirmed through the change of color from light yellow to deep brown of silver nitrate solution with S. hispanica seed extract. Characterization of silver nanoparticles was done through UV-Vis spectrophotometer, Atomic force Microscopy (AFM), Zeta size number, Zeta potential, Transmission Electron Microscopy and Scanning Electron Microscopy. S. hispanica based AgNPs were evaluated through agar well diffusion method, MIC (minimum inhibitory concentration) as well as against experimental infection in rats. UV-Vis spectrophotometer depicted wavelength at 420nm confirmed that particles were synthesized in Nano range. AFM showed spherical and square shapes nanoparticles with 80-120nm average size and 45mV charge. TEM were used to study spherical shape particle size 50-120nm at different resolution (100, 300, 500 nm). Similarly, SEM also depicted average particle size 80-130nm with spherical shape. Silver nanoparticles against enterotoxigenic Escherichia coli (ETEC) and Vibrio cholerae (V. cholerae) through a gar well diffusion method exhibited the greatest antibacterial activity against ETEC as compared to V. cholerae. The MIC against ETEC was 100µg/ml while MIC against V. cholerae was 25µg/ml. Finally, a single dose of AgNPs was administered orally to adult rats colonized with ETEC and V. cholerae, which significantly reduced the rate of colonization by the pathogens 75 or 100 folds, respectively. It was concluded that a S. hispanica based AgNPs have significant antibacterial effect, which may be considered as an effective alternate of antibiotics in future.