The Gold nanoparticles have been synthesized using the leaf aqueous extract of Antigonon leptopus Hook. & Arn. and the phytocomponents were identified from methanolic leaf extracts. Characterization and evaluation of their biological properties have been carried out. The Gold nanoparticles and methanolic leaf extract of the Mexican creeper, Antigonon leptopus were treated on fish pathogens, clinical pathogens and breast cancer cells (MCF-7) in which it resulted significant effects.