Antioxidative and anti-bacterial activities of the essential oils from Perilla frutescens var. Japonica against some foodborne pathogenic bacteria

To develop a new effective and safe, natural antibiotics against antibiotic-resistant food-borne pathogenic bacteria, the essential oil was extracted by steam distillation from the leaves of P. frutescence var. japonica. Its composition was analyzed by GC-MS and the activities against antibiotic-susceptible and -resistant strains of some food-born bacteria which could cause severe clinical symptom in human. In addition we have also determined the capacity of this oil to modulate the resistance of Bacillus and Shigella to antibiotics. As the results, the essential oil fraction of P. frutescence var. japonica L. and its main component, perilla ketone showed significant inhibitory activity against most of the tested strains of antibiotic-susceptible and -resistant bacteria resulting MICs ranged from 0.25˜>2.00mg/ml. The Perilla oils combined with norfloxacin or trimethoperim/sulfamethoxazole showed synergistic or additive effects against the tested Bacillus and Shigella species with FICIs ranging from 0.15˜1.00 in checkerboardtiter test.