Influence of five Chinese herbs on bacterial growth, quorum sensing and biofilm formation

Abstract

Nosocomial pathogens such as Pseudomonas aeruginosa form biofilms to thrive under stress conditions. Biofilm is a community of microorganisms where cells live close to each other and are encased in a protective layer of extracellular polymeric substances against host defenses and antibiotics. Living in the ‘post-antibiotic era’, many pathologists face issues with drug resistance. Herbal phytochemicals have been shown to exhibit anti-bacteria properties towards pathogenic bacteria. Hence, granule and raw herb form of several herb species (Coptis chinensis, Cortex phellodendri, Scutellaria baicalensis, Salvia miltiorrhiza and Rhizoma zingiberis) were extracted by different solvents and screened for the capacities to reduce growth, quorum sensing (QS) and biofilm formation. Raw Rhizoma zingiberis, Salvia miltiorrhiza, Scutellaria baicalensis, Coptis chinensis and Cortex phellodendri demonstrated capacities in reducing growth and QS at various concentrations: such as 33.3, 50, 100, 100, 50μg/ml. Granule Rhizoma zingiberis, Scutellaria baicalensis and Cortex phellodendri demonstrated capacities in reducing growth at various concentrations: such as 66.7, 100, 66.7μg/ml. Granule Rhizoma zingiberis, Scutellaria baicalensis and Cortex phellodendri demonstrated capacities in reducing QS at various concentrations: such as 16.7, 100, 66.7μg/ml. Raw Rhizoma zingiberis, Salvia miltiorrhiza and granule forms of Rhizoma zingiberis, Salvia miltiorrhiza and Cortex phellodendri demonstrated capacities in reducing biofilm formation at various concentrations: such as 2.1, 50, 4.2, 6.25, 66.7μg/ml. These phenotypic traits of each herb from this study provide guidance towards future studies.