Antibacterial potential of garlic-derived allicin and its cancellation by sulfhydryl compounds

Biosci Biotechnol Biochem. 2009 Sep;73(9):1948-55. doi: 10.1271/bbb.90096. Epub 2009 Sep 7.


Allicin (allyl 2-propenethiosulfinate), an antibacterial principle of garlic, has drawn much attention, since it has potent antimicrobial activity against a range of microorganisms, including methicillin-resistant Staphylococcus aureus. There have been many reports on the antibacterial properties of allicin, but no quantitative comparison of antibacterial activities between freshly prepared garlic extract and clinically useful antibiotics has been performed. To verify the substantial antibacterial effect of aqueous garlic extract, we compared it with those of allicin and several clinically useful antibiotics using two representative bacteria commonly found in the human environment, Gram-positive S. aureus and Gram-negative Escherichia coli. The garlic extract had more potent anti-staphylococcal activity than an equal amount of allicin. In terms of antibiotic potency against Gram-positive and Gram-negative bacteria, authentic allicin had roughly 1-2% of the potency of streptomycin (vs. S. aureus), 8% of that of vancomycin (vs. S. aureus), and only 0.2% of that of colistin (vs. E. coli). The antibacterial activity of allicin was completely abolished by cysteine, glutathione and coenzyme A, but not by non-SH-compounds. The oxygen in the structure (-S(=O)-S-) of allicin therefore functions to liberate the S-allyl moiety, which might be an offensive tool against bacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / antagonists & inhibitors
  • Anti-Bacterial Agents / pharmacology*
  • Chromatography, High Pressure Liquid
  • Garlic / chemistry*
  • Gram-Negative Bacteria / drug effects
  • Gram-Positive Bacteria / drug effects
  • Mass Spectrometry
  • Microbial Sensitivity Tests
  • Plant Extracts / pharmacology*
  • Sulfhydryl Compounds / pharmacology*
  • Sulfinic Acids / antagonists & inhibitors
  • Sulfinic Acids / pharmacology*


  • Anti-Bacterial Agents
  • Plant Extracts
  • Sulfhydryl Compounds
  • Sulfinic Acids
  • allicin