title: Garlic natural health products exhibit variable constituent levels and antimicrobial activity against Neisseria gonorrhoeae, Staphylococcus aureus and Enterococcus faecalis.
abstract: The composition of 19 garlic natural health products (NHPs) and fresh garlic extracts were determined, as was their antibacterial activity. The 19 NHPs and 5 fresh garlic extract standards were analysed for their principal active constituents. They were also extracted for 5, 10 or 15 min in water to fresh garlic equivalents of 200 mg/mL. The extract's minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against three indicator microorganisms (Neisseria gonorrhoeae, Staphylococcus aureus and Enterococcus faecalis) were determined by the broth microdilution method. While 47% of the aqueous garlic NHP extracts exhibited activity against N. gonorrhoeae, only 16% of the aqueous extracts inhibited S. aureus or E. faecalis at all three timepoints. Generally, products with high antimicrobial activity contained higher levels of garlic constituents with comparable activity to fresh garlic extracts, while products with marginal antibacterial activity often contained lower concentrations of constituents than their product labels indicated. Different extraction times affected antibacterial activity only against N. gonorrhoeae and tended to be correlated with levels of allicin. Thus, many extracts showed discrepancies in both composition, allicin:alliin ratio and antimicrobial activity, raising concerns as to standards of preparation and quality control for these products.
authors.affiliation: Department of Biology, University of Ottawa, P.O. Box 450, Stn A, Ottawa, ON, K1N 6N5, Canada.
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Ruddock
authors.forename: Mingmin
authors.initials: M
authors.lastname: Liao
authors.forename: Brian C
authors.initials: BC
authors.lastname: Foster
authors.forename: Larry
authors.initials: L
authors.lastname: Lawson
authors.forename: John T
authors.initials: JT
authors.lastname: Arnason
authors.forename: Jo-Anne R
authors.initials: JA
authors.lastname: Dillon
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D013293:Enterococcus faecalis / Q000187:drug effects; D005737:Garlic; D006801:Humans; D008826:Microbial Sensitivity Tests; D009344:Neisseria gonorrhoeae / Q000187:drug effects; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts