International Journal of Plant Science and Ecology Vol. 1, No. 5, 2015, pp. 225-230 http://www.aiscience.org/journal/ijpse * Corresponding author E-mail address: deepakganjawala73@yahoo.com (D. Ganjewala), dganjewala@amity.edu (D. Ganjewala) Synthesis of Silver Nanoparticles from Cymbopogon flexuosus Leaves Extract and Their Antibacterial Properties Ashish Kumar Gupta, Deepak Ganjewala * Amity Institute of Biotechnology, Amity University Uttar Pradesh (AUUP), Noida, India Abstract Here we report synthesis of silver nanoparticles using leaf extracts of four varieties of lemongrass (Cymbopogon flexuosus) namely krishna, neema, pragati and suvarna and their antibacterial activities against drug resistant bacteria Staphylococcus aureus, Pseudomonas aeruginosa and Acinatobacter bamunnii. Silver nanoparticles were synthesized by the bio-reduction of silver nitrate solution (1 mM) using water extracts of lemongrass leaves. Synthesis of silver nanoparticles was confirmed by the presence of an absorbance peak at 430-450 nm in UV-visible spectrum. Thus synthesized silver nanoparticles were analyzed by Dynamic Light Scattering (DLS) technique which revealed their z-average (nm) size 40-100 nm. The silver nanoparticles were tested for their antibacterial potential against drug resistant bacteria by agar well diffusion method. The results revealed that all the silver nanoparticles (4 mg/ml) tested exhibited strong antibacterial activities against S. aureus and P. aeruginosa with zone of inhibition ranged from 24-27 and 17-23 mm, respectively while less effective against A. bamunnii with zone of inhibition ranged 13-14 mm. In conclusion, lemongrass leaf extract can be used to synthesize silver nanoparticles of potential antibacterial activities against drug resistant bacteria. Keywords Antibacterial, Lemongrass, Silver Nanoparticles, Bio-Reduction, Drug Resistant Bacteria, Zone of Inhibition Received: June 28, 2015 / Accepted: July 18, 2015 / Published online: August 13, 2015 @ 2015 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY-NC license. http://creativecommons.org/licenses/by-nc/4.0/ 1. Introduction Cymbopogon flexuosus (Steud.) is popularly known as lemongrass and locally as Cochin or Malabar grass is a tufted perennial grass (Weiss, 1997). It is grown in Kerala, Assam, Maharashtra and Uttar Pradesh. Apart from India, it is also cultivated in large scale in Brazil, Mexico, Dominica, Haiti, Madagascar, Indonesia and China (Ganjewala et al., 2008). Some elite cultivars of lemongrass are krishna, cauveri, pragati, chirharit, neema and suvarna which produce essential oil of wide applications in flavors, pharmaceutical and food industries. Lemongrass essential oil is mainly consisted of a monoterpene aldehyde citral (racemic mixture of two isomers called geranial and neral) which accounts for 75-85% of total monoterpene (Ganjewala and Gupta, 2013). Citral imparts characteristic lemon like aroma to the essential oil and is one of the most important constituent in flavors, fragrance and perfumery, for the synthesis of vitamin A and β-ionones (Dawson, 1994; Ganjewala et al., 2008; Ganjewala et al., 2012). Lemongrass leaf extract, essential oil and its constituents namely citral, geraniol, and geranyl acetate have been reported to possessed a number of bioactivities viz., antimicrobial, anti-inflammatory, anticancer, antioxidant, allelopathic, anthelmintic, and insect and mosquito repellent (Ganjewala et al., 2012; Ganjewala and Gupta, 2013). Lemongrass leaf extract can also be used for the synthesis