NEW YORK (Reuters)—Scientists in Israel may have uncovered
one of the molecular secrets behind the infection-fighting ability of
crushed garlic.
Their study of garlic's active ingredient allicin—the
compound also responsible for garlic's characteristic smell -- shows it
prevents dysentery-causing amebas from doing their dirty work in hamster
kidney cells by blocking two groups of enzymes crucial to the parasite's
functioning.
The enzymes include cysteine proteinases, which provide
infectious organisms with the means to damage and invade tissues. The
others, alcohol dehydrogenase enzymes, are important to the organism's
digestion, thus to its metabolism and survival.
In a report in the journal Antimicrobial Agents and Chemotherapy,
researchers led by Dr. Serge Ankri of the Weizmann Institute of Science,
Department of Membrane Research and Biophysics, point out that the
enzymes are common to a wide variety of bacteria, fungi, and viruses,
and that crushed garlic has been used for fighting infection through the
ages.
"Our present findings shed more light on the remarkable mode of
action of allicin on Entamoeba histolytica (an amebic parasite) and lend
further support to the reasons for the widespread use of allicin and
fresh garlic extracts since ancient times as broad-spectrum, natural
antimicrobial agents," they state.
Ankri and his colleagues note that E. histolytica causes more
than 50 million cases of intestinal dysentery each year. They note that
allicin works against the parasite mainly by blocking cysteine
proteinase activity. They say the blocking of the other enzymes probably
contributes to the "overall lethal effect of allicin" against the
organism.
In another study slated to appear in the journal Biochimica
Biophysica Acta, the Weizmann researchers found that allicin blocks the
enzymes by reacting with one of their important
components—sulfhydryl (SH) groups, or thiols.
Because these thiols participate in the body's synthesis of
cholesterol, allicin may also be useful in preventing
atherosclerosis—the disease process where fatty plaques narrow
arteries.
"It has been suggested that garlic lowers the level of harmful
cholesterol, and our study provides a possible explanation for how this
may occur," says co-author Dr. Meir Wilchek, dean of the institute's
biochemistry faculty. "However, more research is necessary to establish
what role allicin might play in preventing the clogging up of arteries."
SOURCE: Antimicrobial Agents and Chemotherapy
(1997;41(10):2286-2288)