Bacterial infection causes diseases in humans. Disease-causing bacteria upon invading the body, if left untreated, will weaken the body and may be life threatening. Antibiotic drugs such as Penicillin have been commonly used to treat bacterial infection. However, due to the development of antibiotic resistant bacteria, the trend is now focusing on using natural compounds with antibacterial property to treat bacterial infection.
In 1996, a group of researchers in Japan conducted a study on a wider range of antifungal and antibacterial activity of ajoene. The preparation and isolation of ajoene was carried out according to the method described by Block et al.
It was found that ajoene is an effective antibacterial agent and is potent against a broad range of harmful bacteria such as Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Mycobacterium smegmatis, Mycobacterium phlei, Streptococcus sp., Streptomyces griseus, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Xanthomonas maltophilia.
Thus, it was suggested that ajoene, which also contains a sulfinyl group, is thought to possess an antimicrobial effect similar to allicin due to the presence of both the disulfide bond and sulfinyl group.
It was not until recently that ajoene was shown to work as a quorum sensing (QS)-inhibitor by preventing bacteria biofilm growth. In 2005, Bjarnsholt et al demonstrated the garlic extract property which is similar to the QS-inhibitor in promoting rapid clearing of Pseudomonas aeruginosa infection in mice. Several years later, a team led by Jakobsen (2012) identified ajoene as the major active component in garlic extract to attenuate the virulence of P. aeruginosa.