ANTIBACTERIAL
The first microbiological tests with allicin as a perfectly characterized substance were made by his discoverer Chester Cavallito and coworkers (1). The results showed a broad activity against Gram positive and Gram negative bacteria and fungi. Allicin was an efective inhibitor of the bacteria V cholerae, B typhosus, and B. disenteriae , among others. Its activity was lower than of penicillin,the “star” antibiotic at those years (1944), and this was, perhaps, the reason why the discover of Cavallito did not receive the attention that deserved by the scientific community.
Since the allicin's discovery there have been relatively scarce studies on the mechanism of inhibition of allicin on bacterial growth. The commonly accepted theory is that allicin can react with sulfhydril groups of certain enzimes making them inactive. Recently, R. Feldberg (2)et al have made a study of inhibition of growth of salmonella typhimurium by allicin and they found a growing inhibiton stage with a duration depending on allicin's concentration and cell culture density. After this period, the growth resumed (but did not reach the density levels of the control samples without allicin). A special finding was the inhibition curves were acompanied by a drop in the RNA synthesis to about 1% of the initial synthesis rate. Then the RNA production rose to similar control values

ANTITHROMBOTIC
Allicin inhibits platelet aggregation (3). The mechanism of action has not been fully elucidated, but studies by Mayeux et al. indicates that allicin can produce vasodilatation in a similar fashion that of calcium channel blockers,and a inhibition of calcium uptake into platelets. These authors suggest the use garlic extracts (with allicin) to prevention of hypertension,and stroke.

ALLICIN AND BIOFILM

º Yeast
Studies with fresh garlic extracts (allicin) showed biofilm inhibition in Candida albicans (4).
º Bacteria
Allicin has proven as an effective biofilm inhibitor in the bacteria Staphilococcus epidermidis. (5)



References

1.Small, L.V., Bayley, J.H., and Cavallito,C. 1947 Alkyl thiosulfinates. 1947 J. Am. Chem. Soc,69,1710-1713

2. Feldberg,R.,Chang,S.C.,Kotik,A.N,Nadler,M.,Neuwirth,Z,Sundtrom,D.C, Thompson,N.H. 1988. In vitro mechanism of inhibition of bacterial cell growth by allicin. Antimicrob.Agents.Chemoter. 32,No 12,1763-1767

3.Mayeux,P.R.,Agrawal,K.C.,Tou,J.S.H,King,B.T.,Lippton,H.LHyman,A.L.,Kadowitz,P.J. 1988 The pharmacological effects of allicin,a constituent of garlic oil.Agents and Actions25,183-190

4.Shuford J. A, Steckelberg J. M, Patel.R 2005 Effects of Fresh Garlic Extract on Candida albicans Biofilms Antimicrob.Agents.Chemoter. 49,473

5.Cruz Villalon, G. 2010 Doctoral thesis, University of Extremadura, Spain., "Efecto de la alicina sobre el crecimiento y produccion de biocapas en Staphylococcus epidermidis."

6.*Zhai H, Pan J, Pang E, Bai B 2014 Lavage with allicin in combination with vancomycin inhibits biofilm formation by Staphylococcus epidermidis in a rabbit model of prosthetic joint infection. PLoS One;9(7):e102760

*antibiotic+allicin, good combination!
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