Zingiber officinale (Ginger) Compounds Have Tetracycline-resistance Modifying Effects Against Clinical Extensively Drug-Resistant Acinetobacter baumannii

Extensively drug-resistant Acinetobacter baumannii (XDRAB) is a growing and serious nosocomial infection worldwide, such that developing new agents against it is critical. The antimicrobial activities of the rhizomes from Zingiber officinale, known as ginger, have not been proven in clinical bacterial isolates with extensive drug-resistance. This study aimed to investigate the effects of four known components of ginger, [6]-dehydro-gingerdione, [10]-gingerol, [6]-shogaol and [6]-gingerol, against clinical XDRAB. All these compounds showed antibacterial effects against XDRAB. Combined with tetracycline, they showed good resistance modifying effects to modulate tetracycline resistance. Using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method, these four ginger compounds demonstrated antioxidant properties, which were inhibited by MnO2, an oxidant without antibacterial effects. After the antioxidant property was blocked, their antimicrobial effects were abolished significantly. These results indicate that ginger compounds have antioxidant effects that partially contribute to their antimicrobial activity and are candidates for use in the treatment of infections with XDRAB. Copyright (C) 2010 John Wiley & Sons, Ltd.