Globally, particularly in developing countries because over exploitation of natural resources, many of the medicinal plants are extinct or endangered. Multi uses of medicinal plants and increases in demand are the key factor for their extinction. In order to conserve natural biodiversity, it is essential to maintain and protect the medicinal plants for future use, clonal propagation methods have been used developed for selected medicinal plants such as Vitex negundo, Aloe vera, Careya arborea, Red Banana and Stevi rebaudiana.Established green synthesis methods for synthesis of silver and gold nanoparticles from in vitro clonal propagated plants of Vitex negundo & Red banana, plantlets (cultures) of selected medical plants of Aloe vera & Stevia rebaudiana and suspension cultures of Careya arborea and being used as extracts. Green synthesized SiNPs and GNPs were characterized for determination of their sizes, shapes, zeta potential, surface charge and stability by UV Visible Spectroscopy, FTIR, DLS, AFM and XRD and the effects of SiNPs and GNPs on the microbial species were investigated via formation of Zone of Inhibition, disc and well plate methods.