Garlic natural health products exhibit variable constituent levels and antimicrobial activity againstNeisseria gonorrhoeae, Staphylococcus aureus andEnterococcus 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.

Antibacterial Activity of Allicin Alone and in Combination with β-Lactams against Staphylococcus spp. and Pseudomonas aeruginosa

“…The efficacy of many antibiotics for treatment of severe infections has become quite limited due to the development of resistance. Allicin, one of the main effective antibacterial ingredients isolated from garlic, has also shown little adverse reaction, no antigenicity, and some immuno-modulation activity [19,20]. Many published data indicate that allicin has certain in vitro antibacterial activity but the MICs are often relatively high, limiting its clinical utility [21ϳ23].…”

Antimicrobial Resistance in Neisseria gonorrhoeae in the 21st Century: Past, Evolution, and Future

“…For example, the activities of many of these have not been examined against XDR or MDR gonococcal isolates, particularly those with ESC resistance or high-level azithromycin resistance. Furthermore, despite the fact that a breakthrough is lacking, as part of "thinking outside the box," it can be important to continuously evaluate appropriate plant extracts for in vitro activity against gonococci and, subsequently, for treatment of gonorrhea (136,(333)(334)(335)(336)(337)(338)(339)(340)(341)(342)(343)(344)(345). All novel potential treatment regimens for gonorrhea require up-to-date and comprehensive in vitro and, subsequently, in vivo evaluations, including appropriately designed, randomized, and controlled clinical trials to evaluate parameters such as efficacy, safety, toxicity, cost, optimal dose, and pharmacokinetic/pharmacodynamic data for genital and extragenital (especially pharyngeal) gonorrhea.…”

Evaluation of the Antimicrobial Activity of Tribulus terrestris, Allium sativum, Salvia officinalis, and Allium hirtifolium Boiss Against Enterococcus faecalis

“…This finding was in accordance with the studies by Ruddock et al and Ruiz et al who worked on the effect of A. sativum extract on E. coli, S. typhimurium, Neisseria gonorrhoeae, S. aureus, and E. faecalis. 46,47 Our study revealed that the autoclave temperature eliminated the antibacterial effect of A. sativum extract. However, this effect was not considered in the studies by Ruddock et al and Ruiz et al This can be related to the heat-induced destruction of allicin, the thermolabile antibacterial compound in garlic.…”