Chemical Composition of Essential Oils and in vitro Antibacterial Activity of Methanolic Extracts of Sonchus arvensis and Eremurus spectabilis Against Four Food-borne Pathogenic Bacteria

In this experimental study, chemical composition of essential oils of aerial parts of Sonchus arvensis and roots of Eremurus spectabilis was determined and antibacterial effects of methanolic extracts of these plants were evaluated on some strains of Gram-positive and Gramnegative bacteria. The hydro-distilled essential oil from aerial parts of S. arvensis was analyzed by gas chromatography and mass spectrometry (GC-MS) technique. The antimicrobial activity of the aerial parts methanolic extracts of S. arvensis and roots of E. spectabilis was screened by disk diffusion and macrodilution method was used for determination of MIC and MBC. The bacterial strains were Bacillus cereus PTCC 1015, Staphylococcus aureus PTCC 1431, Salmonella enterica PTCC 1709 and Escherichia coli PTCC 1399. The serial dilutions of the oil from 3.125 to 400 mg/ml were prepared in 96 wells micro plates using Mueller-Hinton broth for macrodilution. Thirty-five compounds of the hydro-distilled essential oil from aerial parts of S. arvensis were identified, representing 99.82 % of the total oil. N-Octane (29.82%), n-Decane (11.09%) were the main components. The MIC and MBC varied from 12.5 to 100 and 100 to >400 mg/ml for all Gram-positive and Gram-negative bacteria, respectively. The best MIC and MBC observed against S. aureus (12.5 and 100 mg/ml, respectively). Result shows that the methanolic extracts of S. arvensis and E. spectabilis could inhibit the growth of Gram-positiveand Gram-negative bacteria. However, the inhibitory effect of these plants on Gram-positive is more than Gram-negative.

Keywords:

Sonchus arvensis , Eremurus spectabilis , antimicrobial effect , GC-MS