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.

This is the first report of the antibacterial activity of Columbian plants against NG. The activity of the 2 flavonoids, pinocembrin, and pinocembrin chalcone, toward both susceptible and resistant NG strains makes them promising candidates for further research.

The peptide HE2alpha, which is derived from the male urogenital tract, exhibits antibacterial activity against both gram-positive and gram-negative pathogens in vitro. The peptide is active against both antibiotic-susceptible and -resistant N. gonorrhoeae isolates. Further investigation of the antimicrobial properties of the peptide is warranted.

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