Effect of culture media on chemical stability and antibacterial activity of allicin

Abstract

Minimum Inhibitory Concentration (MIC) of allicin were determined for 11 bacterial strains using 6 culture media including Todd Hewitt Broth (THB), Brain Heart Infusion (BHI) Broth, Tryptic Soy Broth (TSB), Mueller Hinton Broth (MHB), Luria Bertani (LB) Broth, and Brucella Broth (BB) at 37°C. The chemical stability of allicin as a function of media was measured by HPLC. The MICs for most individual isolates grown at the same temperature varied with the media used. Higher MICs were obtained in BB, THB, BHI, TSB/MHB and LB with geometric mean values of 272.7, 145.2, 90.5, 77.3/72.6 and 46.7μgml−1 respectively. In media with higher MICs a big percent of allicin disappeared within the first 4h of incubation and apparently allicin had shorter half-life compared to those with lower MIC values. The results showed that temperature directly influences the stability of allicin and shorter half-life was found at 37°C.We conclude that the type of culture media, markedly influences the chemical stability of allicin and accordingly its MIC in a given bacterial species.