Posted by: Hourglass PJ5 MAR 2014
Garlic has been cultivated for thousands of years, both for culinary purposes and for its medicinal properties.
One of its traditional medical uses lies in the treatment of infection. Although scientific evidence to date has not in my opinion been strong enough to recommend whole garlic for the treatment of infection, during the past three decades researchers have tested garlic compounds in vitro and increasingly found them effective against both bacterial and fungal infections.
Allicin has often been considered to be the most pharmacologically active ingredient in garlic, but it is ajoene, a garlic compound perhaps less well known to the non-specialist, that is most associated in scientific studies with both antibacterial and antifungal activity.
Most recently, ajoene has been identified as having specific activity against antibiotic-resistant bacteria. Given the paucity of new antibiotics appearing on the scene, ajoene could become a useful tool in the management of antibiotic-resistant infections, which are rapidly becoming one of the world’s greatest health problems. This recent work on garlic has been done by Danish PhD student Tim Holm Jacobsen, who has found that ajoene counteracts resistant bacteria by paralysing their communication system.
Pathogenic bacteria such as Pseudomonas aeruginosa have a communication system known as quorum sensing (QS), which is responsible for their pathogenicity. Mr Jacobsen tested garlic and its various compounds to find that ajoene specifically targets one component of the QS system, the toxin rhamnolipid. Rhamnolipid destroys white blood cells and, since white blood cells are indispensable for immune defence and killing bacteria, ajoene could find a use in treating infection.
However, it is only when ajoene is combined with an antibiotic that a significant effect occurs. When bacteria clump together they surround themselves with a tough film of organic materials and become resistant to antibiotics. When antibiotics are added to this biofilm in laboratory studies, nothing happens and when ajoene is added nothing happens. But, according to this new work, ajoene combined with an antibiotic can eradicate more than 90 per cent of the tough biofilm. Ajoene works by blocking the bacterial QS system, which the bacteria use in the development of an infection.
So should we consume more garlic? Well, garlic actually contains so little ajoene that you would need to eat 50 cloves each day to achieve an antibacterial effect.
But it may be that a product could be developed from this natural substance that could be part of the antibacterial armamentarium, together with existing antibiotics, for treating resistant infection.