title: Enhanced antibacterial activities of leonuri herba extracts containing silver nanoparticles.
abstract: We report an efficient and powerful green process to enhance the antibacterial activities of the Leonuri herba extract. Plant sources, especially leaves and herbs, are precious for the generation of gold and silver nanoparticles. Various kinds of polyphenols and hydroxyl groups are capable of processing a reduction reaction to generate metals from its corresponding salts. We have prepared gold and silver nanoparticles with 70% ethanol and water extracts. No other toxic chemicals were utilized and the extracts played dual roles as reducing and stabilizing agents. For the generation of nanoparticles, both oven incubation and autoclaving methods were applied and the reaction conditions were optimized. Surface plasmon resonance band indicated that the formation of nanoparticles was successful. Images of high-resolution transmission electron microscopy revealed mostly spherical nanoparticles ranging from 9.9 to 13.0 nm in size. A water extract containing silver nanoparticles exhibited remarkable (approximately 127-fold) enhancement in antibacterial activities against Pseudomonas aeruginosa, Escherichia coli and Enterobacter cloacae when compared with the water extract alone. In addition, antibacterial activity towards Gram-negative bacteria was greater than that against Gram-positive bacteria. The process reported here has the potential to be a new approach to improve the antibacterial activities of plant extracts.
authors.affiliation: Natural Products Research Institute, College of Pharmacy, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: A-Rang
authors.initials: AR
authors.lastname: Im
authors.forename: Lina
authors.initials: L
authors.lastname: Han
authors.forename: E Ray
authors.initials: ER
authors.lastname: Kim
authors.forename: Jinwoong
authors.initials: J
authors.lastname: Kim
authors.forename: Yeong Shik
authors.initials: YS
authors.lastname: Kim
authors.forename: Youmie
authors.initials: Y
authors.lastname: Park
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D016972:Enterobacter cloacae / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D000431:Ethanol / Q000737:chemistry; D006046:Gold / Q000737:chemistry / Q000494:pharmacology; D031332:Leonurus / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D059808:Polyphenols / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology; D013010:Sonication; D020349:Surface Plasmon Resonance; D014867:Water / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D059808:Polyphenols; D014867:Water; D000431:Ethanol; D012834:Silver; D006046:Gold