GREEN SYNTHESIS, CHARACTERIZATION, ANTIMICROBIAL AND CYTOTOXIC EFFECTS OF SILVER NANOPARTICLES USING ORIGANUM HERACLEOTICUM L. LEAF EXTRACT Original Article RAVIKUMAR RAJENDRAN 1 , NITHYA GANESAN 2 , SATHEESH KUMAR BALU 3 , SRINIVASAN ALAGAR 4 , PREMKUMAR THANDAVAMOORTHY 1 , DEVAKI THIRUVENGADAM 1 * 1 Department of Biochemistry, Guindy Campus, University of Madras, Chennai 600025, TN, India, 2 Bharathidasan University, Trichy, TN, India, 3 Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi, TN, India, 4 Received: 28 Jan 2015 Revised and Accepted: 25 Feb 2015 Department of Nanoscience and Technology, Alagappa University, Karaikudi, TN, India Email: devakit@yahoo.co.uk ABSTRACT Objectives: Silver nanoparticles (AgNPs) possess unique features among noble metal nanoparticles due to their wide range of applications in various field including medicine, environmental safety, etc. The present study relies on eco-friendly, cost effective method for the synthesis of AgNPs. Methods: AgNPs were rapidly synthesized from AgNO 3 Results: X-ray diffraction analysis showed that the nanoparticles formed in the present synthesis were crystalline in nature. FT-IR analysis showed the presence of possible biomolecules needed for reducing silver ions. Further, antibacterial activity of synthesized AgNPs showed effective inhibition against pathogenic microbes. In addition, these green synthesized nanoparticles were shown to exhibit potential cytotoxic effect on MCF- 7 cell line in dose dependent manner. using aqueous leaf extract of O. heracleoticum L. as reducing as well as capping agent. Synthesized AgNPs were characterized with the help of FE-SEM, XRD, EDS and UV–vis absorption spectroscopy. FE-SEM showed the spherical nature of nanoparticles with the size ranging from 30-40 nm. In addition, their antibacterial activities against standard bacterial pathogens were evaluated as per the standard disk diffusion method. Further, cytotoxicity potential of AgNPs were also determined using the MTT assay. Conclusion: It has been demonstrated that O. heracleoticum L. plant extract could be used as a proficient green reducing agent for the synthesis of AgNPs. Further, these synthesized AgNPs were shown to exhibit effective antibacterial effect against pathogens and potential cytotoxic effect on MCF-7 cells. Keywords: AgNPs, O. heracleoticum L., Aqueous extract, Pathogenic microbes, Cytotoxicity. INTRODUCTION For the past 40 years, the foundations were set down for nanotechnologies to deliver diagnostic and therapeutic agents in a secure and more systematic manner [1]. Attaining this prescience became more pragmatic in recent years, with increasing numbers of nano based therapeutics and diagnostics being profit-oriented or having reached clinics [2]. Advances in Nanoscience are promptly enabling the evolution of nanoparticles with distinct properties which address the limitations of traditional disease diagnostic and therapeutic agents [3]. In 1959, Richard P. Feynman, Physicist at California Institute of Technology stated that "There is plenty of room at the bottom" starting from atomic level and scaling down to the nanolevel which provides a route to forthcoming technology and advancement. From there, Nanotechnology has now educed into much innovation in all areas of Science including Medicine, new therapeutic, tissue engineering, diagnostic concepts, drug delivery, gene silencing and vehicles for targeted drug delivery system [4, 5]. Nanomedicines were declared to augment adequacy, specificity, durability and therapeutic index of analogous drugs [6, 7]. Nanoparticles have immense application including their use in highly sensitive diagnostic assays, drug and gene delivery, thermal ablation and radiotherapy enhancement, antimicrobial agents, sensors, optical, electronic, and catalytic application [8]. Green synthesis and characterization of nanoparticles have attained a notable segment of Nanotechnology in the past decade, peculiarly for noble metals such as Au, Ag, Pt and Pd. Moreover, the physical or chemical approaches are normally engaged to synthesize metal nanoparticles because of their indelible benefit in assembling well- defined NPs with quite tractable sizes and shapes. These methods involve more expensive and tedious treatments such as laser ablation, hydrothermal synthesis, solvothermal synthesis, pyrolysis and inert gas condensation [9]. In contrast to this, several research groups have brought about success in the synthesis of NPs profit by biological raw materials, an alternative to lethal chemicals and the expensive physical methods. At present, feasible initiatives that use green Chemistry to enhance and/or protect our surroundings are becoming important affair in various fields of research. Natural products exhibit one of the most abiding approaches to this goal. Plants have been confirmed to be one of affluent sources of natural products. Moreover, using this kind of approaches represent a development of nature-friendly and cost-effective approach [10]. Metal nanoparticles have received great attention due to their eccentric and unusual physico-chemical properties. At present, synthesis of nanoparticles is a crucial area of research, probing for a nature-friendly manner for current science. Countless methodologies are emerged to synthesize noble metal nanoparticles of specific shape and size depending upon requirement. Green synthesis of nanoparticles has an emerging acme of junction between Biotechnology and Nanotechnology which has earned notable attention to a growing need to establish environmentally amiable technologies in nanoparticle synthesis [11, 12]. In particular, extracts obtained are more beneficial because using them eliminates the tedious process of maintaining cell cultures and can be suitably restrained for extensive production under non aseptic environments. Amongst various metal nanoparticles, AgNPs are globally recognized owing to its immense range of applications in biosensing, photonics, photocatalysis, pharmaceuticals, micro- electronics, etc [13]. In addition, AgNPs have shown to exhibit antifungal, antiviral, antibacterial, antiplatelet, anti-inflammatory and anticancerous activity [14]. The boundless antimicrobial properties of AgNPs encourage its potential in a large number of environmental and biomedical applications as well as in clothing, cosmetics and different consumer products [15]. Several research papers reported the synthesis of silver nanoparticles using plant International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 7, Issue 4, 2015 Innovare Academic Sciences