Bactericidal activities against pathogenic bacteria by selected constituents of plant extracts in carrot broth

• Published in: Food chemistry Vol. 128; no. 4; pp. 872 - 877
• Main Authors: Vegara, S., Funes, L., Martí, N., Saura, D., Micol, V., Valero, M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15-10-2011; Elsevier
• Subjects: antibacterial properties; bacteria; Biological and medical sciences; carrots; Daucus; Escherichia coli; Food industries; Food microbiology; Foodborne pathogens; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Lippia; Lithospermum erythrorhizon; MIC50; Microplate dilution method; model food systems; Natural antimicrobials; Plant extracts; Rheum; Rheum palmatum; Rosmarinus officinalis; Salvia; Staphylococcus aureus; Thymus mastichina; Thymus vulgaris; Natural antimicrobials; Foodborne pathogens; Microplate dilution method; MIC50; Plant extracts; Carrot; Vegetables; MIC; Extract; Method; Natural; Antimicrobial agent; Bactericidal effect; Dilution; Pathogenic; Bacteria; Microorganism; Constituent
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2011.03.109

► Isolation and identification of plant extract constituents. ► Determination of MIC50 for Escherichia coli and Staphylococcus aureus. ► Bactericidal activities in a model food system, Tyndallised carrot broth (TCB). ► 15mg/L naphthazarin or 47mg/L shikonin caused 6 log reductions in E. coli counts. ► Rhein and carnosic acid displayed moderate bactericidal effects on S. aureus.
HPLC-DAD analysis provided evidence for the certain identification of some constituents of hydroalcoholic extracts from Lithospermum erythrorhizon, Rheum palmatum, Thymus vulgaris, Lippia citriodora, and a mixture of Rosmarinus officinalis, Salvia lavandulifolia and Thymus mastichina. Their inhibitory and bactericidal activities in vitro against Escherichia coli and Staphylococcus aureus were evaluated either in Luria–Bertani (LB) broth or a model food system, Tyndallised carrot broth (TCB). Shikonin exhibited high inhibitory activity against both microorganisms, but to a lesser extent than the basic unit naphthazarin (5,8-dihydroxy-1,4-naphthoquinone). Rhein and carnosic acid showed noticeable inhibitory effects on S. aureus. In inoculated TCB containing 15mg/L naphthazarin or 47mg/L shikonin there was about 6 log reductions in E. coli counts, while 20mg/L naphthazarin, 26.4mg/L rhein, 45mg/L shikonin or 68.7mg/L carnosic acid caused 1.6, 2.4, 3.1 and 3.1 log reductions in S. aureus inocula, respectively. Log reductions obtained for S. aureus in TCB compared unfavourably with those found in LB broth.