Antifungal and antibacterial activities of allicin: A review

Up until the early twentieth century infectious diseases were the most common and serious health problem worldwide, with degenerative disorders only dominating in certain parts of the world, such as Europe, relatively recently. As one of the most important challenges in the treatment of infection, much attention is currently focused on natural products as an alternative strategy against antibiotic resistance, due to their high therapeutic effects and low adverse reactions. Garlic is a well-known spice from the Alliaceae family that is widely used in traditional medicine for its wide variety of therapeutic properties, especially its potent antimicrobial effects. This species contains a unique class of organosulfur compound called allicin. A wide range of evidence has revealed the therapeutic effect of this compound on fungal and bacterial infection. This paper critically reviews the available evidence of the antifungal and antibacterial activities of allicin. Its chemistry, bioavailability and natural sources are also discussed. During the past two decades, much attention has been focused on the antibacterial and antifungal potential of allicin against multi-drug resistant microorganisms. Despite promising in vitro results, the in vivo activity of allicin has not yet been well documented in preclinical and clinical efficacy trials. Due to some adverse effects, further studies are required to confirm the potential therapeutic use of allicin as an antimicrobial agent. Pharmacokinetic studies should be performed in order to improve the bioavailability of allicin by employing different delivery systems.