Natural Products Research Institute, College of Pharmacy, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul 151-742, Republic of Korea.
Phytother Res. 2012 Aug;26(8):1249-55. doi: 10.1002/ptr.3683. Epub 2011 Dec 15.
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.
我们报道了一种高效、强大的绿色工艺，可增强益母草提取物的抗菌活性。植物来源，特别是叶子和草药，是生成金和银纳米粒子的宝贵资源。各种多酚类化合物和羟基基团能够进行还原反应，将金属从其相应的盐中生成。我们已经用 70%乙醇和水提取物制备了金和银纳米粒子。没有使用其他有毒化学物质，提取物同时起到了还原和稳定剂的双重作用。为了生成纳米粒子，我们应用了烤箱孵育和高压灭菌两种方法，并对反应条件进行了优化。表面等离子体共振带表明纳米粒子的形成是成功的。高分辨率透射电子显微镜的图像显示，大多数纳米粒子为球形，尺寸在 9.9 到 13.0nm 之间。与单独的水提取物相比，含有银纳米粒子的水提取物对铜绿假单胞菌、大肠杆菌和阴沟肠杆菌的抗菌活性显著增强（约 127 倍）。此外，对革兰氏阴性菌的抗菌活性大于对革兰氏阳性菌的抗菌活性。这里报道的方法有可能成为提高植物提取物抗菌活性的一种新方法。
