Evaluation of Synergistic Antibacterial and Antioxidant Efficacy of Essential Oils of Spices and Herbs in Combination

PLoS One. 2015 Jul 1;10(7):e0131321. doi: 10.1371/journal.pone.0131321. eCollection 2015.

Abstract

The present study was carried out to evaluate the possible synergistic interactions on antibacterial and antioxidant efficacy of essential oils of some selected spices and herbs [bay leaf, black pepper, coriander (seed and leaf), cumin, garlic, ginger, mustard, onion and turmeric] in combination. Antibacterial combination effect was evaluated against six important food-borne bacteria (Bacillus cereus, Listeria monocytogenes, Micrococcus luteus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) using microbroth dilution, checkerboard titration and time-kill methods. Antioxidant combination effect was assessed by DPPH free radical scavenging method. Total phenolic content was measured by Folin-Ciocalteu method. Bioactivity -guided fractionation of active essential oils for isolation of bioactive compounds was done using TLC-bioautography assay and chemical characterization (qualitative and quantitative) of bioactive compounds was performed using DART-MS and HPLC analyses. Cytotoxic potential was evaluated by brine shrimp lethality assay as well as MTT assay using human normal colon cell line. Results showed that among the possible combinations tested only coriander/cumin seed oil combination showed synergistic interactions both in antibacterial (FICI : 0.25-0.50) and antioxidant (CI : 0.79) activities. A high positive correlation between total phenolic content and antibacterial activity against most of the studied bacteria (R2 = 0.688 - 0.917) as well as antioxidant capacity (R2 = 0.828) was also observed. TLC-bioautography-guided screening and subsequent combination studies revealed that two compounds corresponding to Rf values 0.35 from coriander seed oil and 0.53 from cumin seed oil exhibited both synergistic antibacterial and antioxidant activities. The bioactive compound corresponding to Rf 0.35 from coriander seed oil was identified as linalool (68.69%) and the bioactive compound corresponding to Rf 0.53 from cumin seed oil was identified as p-coumaric acid (7.14%) by DART-MS and HPLC analyses. The coriander/cumin seed oil combination did not show any cytotoxic effect both in brine shrimp lethality as well as human normal colon cell line assays. The LC50 in brine shrimp lethality assay was found to be 4945.30 μg/ml and IC50 in human normal colon cell line was > 1000 μg/ml. The results provide evidence that coriander/cumin seed oil combination might indeed be used as a potential source of safe and effective natural antimicrobial and antioxidant agents in pharmaceutical and food industries.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / isolation & purification
  • Anti-Bacterial Agents / pharmacology*
  • Antioxidants / isolation & purification
  • Antioxidants / pharmacology*
  • Artemia / drug effects
  • Artemia / physiology
  • Biphenyl Compounds / antagonists & inhibitors
  • Biphenyl Compounds / chemistry
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Coriandrum / chemistry*
  • Coumaric Acids / isolation & purification
  • Coumaric Acids / pharmacology*
  • Cuminum / chemistry*
  • Drug Synergism
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects
  • Gram-Negative Bacteria / drug effects
  • Gram-Negative Bacteria / growth & development
  • Gram-Positive Bacteria / drug effects
  • Gram-Positive Bacteria / growth & development
  • Humans
  • Microbial Sensitivity Tests
  • Oils, Volatile / isolation & purification
  • Oils, Volatile / pharmacology*
  • Picrates / antagonists & inhibitors
  • Picrates / chemistry
  • Plant Extracts / chemistry
  • Propionates
  • Spices / analysis

Substances

  • Anti-Bacterial Agents
  • Antioxidants
  • Biphenyl Compounds
  • Coumaric Acids
  • Oils, Volatile
  • Picrates
  • Plant Extracts
  • Propionates
  • 1,1-diphenyl-2-picrylhydrazyl
  • trans-3-(4'-hydroxyphenyl)-2-propenoic acid

Grant support

This work was supported by the University Grants Commission, New Delhi, India provided Post Doctoral Fellowship [F.15-1/2012-13/PDFWM-2012-13-GE-WES-18557(SA-II)] to AB.The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.