Parveen Sulthana et al. 1 © 400 Terminalia chebula Retz. gallic acid – biased silver nanoparticles and their antiphytopathogenic activity A. Parveen Sulthana 1 , J. Martin Rathi 2* and K. Sahayaraj 3 ABSTRACT Owing to the unique properties, nanomaterials play a major role in many areas of science and technology. In this paper the antiphytopathogenic activity of gallic acid reduced Terminalia chebula Retz. silver nanoparticles (Ag NPs) was studied. AgNO 3 (10 -3 M) stock solution was prepared by dissolving 17mg of silver nitrate in 100ml of double distilled water. 10ml of gallic acid solution isolated from Terminalia chebula Retz. (Combretaceae) was added to 90ml of 10 -3 M AgNO 3 solution for reduction of Ag + ions. The reduction of pure Ag + ions was monitored by measuring in the UV-Vis Spectroscopy at 426nm. Determination of the shape and structure of silver nanoparticle was characterized by Transmission Electron Microscopic (TEM) and X-ray Diffraction studies (XRD). The plasma resonance of the gallic acid reduced silver particle is brownish yellow. In the light of these studies, the shape of the silver nanoparticle (spherical) and face centered cubic (FCC) structure were explained. The antibiotic experiment conducted in the present study revealed the antiphytopathogenic activity of gallic acid reduced Terminalia chebula Retz. silver nanoparticles against the phytopathogen Xanthomonos axonopodis pv. malvacearum and also confirmed the antiphytopathogenic activity studies based on “Broth microdilution method” against Xanthomonos axonopodis pv. malvacearum. MS History: 05.11.2013 (Received)-05.03.2014 (Revised)-17.03.2014 (Accepted) Key words: Terminalia chebula, gallic acid, silver nanoparticles, TEM, XRD, antiphytopathogenic activity. INTRODUCTION Silver has been in use since time immemorial in the form of metallic silver, silver nitrate, silver sulfadiazine for the treatment of burns, wounds and several bacterial infections (Mahendra Rai et al., 2009). But due to the emergence of several antibiotics, the use of these silver compounds has declined remarkably. However silver nanoparticles could be used as a potential alternative therapy to reduce severity of disease due to Pseudomonas aeruginosa infections (Navindra Kumari Palanisamy et al., 2014). Nanotechnology is gaining tremendous impetus in the present century due to its capability to modulate metals into their nanosize, which drastically changes their chemical, physical and optical properties. Hence metallic silver in the form of silver nanoparticles has made a remarkable comeback as a potential antimicrobial agent. The use of silver nanoparticles is also important, as several pathogenic bacteria have developed resistance against various antibiotics. It has diverse medical applications ranging from silver based dressings, silver coated medicinal devices, such as nanogels (Mahendra Rai et al., 2009), nanolotions (Mahendra Rai et al., 2009) etc. The nanocrystalline silver dressings, creams and gel effectively reduce bacterial infections in chronic wounds (Richard et al., 2002; Leaper, 2006; Ip et al., 2006). Silver impregnated medical devices like surgical masks and implantable devices show significant antimicrobial efficacy (Furno et al., 2004). There are numerous works related to green synthesis of metallic nanoparticles using higher plants. Gardea- Toroesday et al., (2003) first reported the formation of silver nanoparticles by living plants. Shankar et al. (2004) reported pure metallic silver nanoparticles synthesis by the reduction of Ag + and Au + ions using neem (Azadirachta indica Juss.) leaf broth. For instance, some of the renowed reports on phytosynthesis of silver nanoparticles by employing lemon grass extract ( Shankar et al., 2004, 2005), green tea, Camellia sinensis (L.) Kuntze (Vilchis- Nestor et al.,2008), Aloe vera (L.) Burm. Plant extract (Chandran et al., 2006), sundried Nanoparticles antiphytopathogenic activity JBiopest 7(Supp.): 1-6 (2014)