Garlic could provide cancer drug

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Last Updated: Wednesday, 31 December, 2003, 00:52 GMT

The chemical which gives garlic its flavour could be used in a "smart bomb" to fight cancer, scientists say.

The finding comes just days after it was revealed the same chemical, allicin, could treat the hospital superbug MRSA.

The cancer treatment harnesses the natural chemical reaction in which allicin is produced.

The journal Molecular Cancer Therapeutics details how the reaction can be triggered at tumour sites.

Allicin is a toxic, but unstable, chemical which breaks down quickly and harmlessly when it is eaten.

It is not present in unbroken cloves of garlic, but is produced as a biochemical reaction between two substances stored apart in tiny, adjoining compartments within each clove - the enzyme, alliinase, and a normally inert chemical called alliin.

If the clove is broken, as it is in cooking, the membranes separating the compartments are broken and allicin is produced.

Chemical reaction

Israeli researchers decided to try to recreate this toxic reaction at the site of a tumour.

To target the treatment, they used an antibody which had been programmed to recognise distinctive receptors on the tumour cells' surface.

The antibody is chemically bound to alliinase and injected into the bloodstream where it seeks out cancer cells.

Alliin is then also injected. When it encounters the alliinase, the resulting reaction turns the alliin molecules into allicin, which penetrates and kills the tumour cells.

Healthy cells nearby are left intact because they have not attracted the antibodies.

The researchers from the Weizmann Institute in Rehovet successfully used the technique to block the growth of stomach tumours in mice.

They say the method could work for most types of cancer, as long as a specific antibody can be designed to recognise receptors unique to the cancer cells.

The technique could prove invaluable for preventing metastasis following surgery.

'Challenge'

Professor David Mirelman, who led the research, said: "Even though doctors cannot detect where metastatic cells have migrated and lodged themselves, the antibody-alliinase-alliin combination should chase them down and destroy them anywhere in the body."

Sara Hiom, a science information manager for Cancer Research UK told BBC News Online: "The medicinal properties of garlic have long been recognised.

"These are encouraging preliminary data. The challenge now will be to develop methods for use against different types of tumour cells and eventually to adapt the technique for use in humans so that the necessary clinical trials can be carried out."

http://news.bbc.co.uk/1/hi/health/3356737.stm

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Weizmann Institute's garlic 'smart bomb' destroys tumor cells in mice

Dec. 31, 2003
By JUDY SIEGEL-ITZKOVICH

A chemical naturally found in garlic has been used by Weizmann Institute researchers to destroy malignant tumors in mice while leaving healthy tissue intact. The key to the scientists' success lies in the development of a two-step system for delivering the cancer-wrecking chemical straight to the tumor cells.

A team of the Rehovot institute's biological chemistry department comprised of Drs. Aharon Rabinkov, Talia Miron and Marina Mironchick, along with Profs. David Mirelman and Meir Wilchek, designed the innovative delivery method that works with the pinpoint accuracy of a smart bomb. Their findings were reported in the December issue of Molecular Cancer Therapeutics.

Allicin is the natural chemical that gives garlic its distinctive aroma and flavor. For many years, scientists studying allicin have known that it is as toxic as it is pungent. It has been shown to kill not only cancer cells but also cells of disease-causing microbes and even healthy human body cells. Fortunately for our body's cells, allicin is highly unstable, and breaks down quickly once ingested. However, the rapid breakdown and undiscriminating toxicity presented twin hurdles to creating an allicin-based therapy.

The method parallels the way allicin is synthesized in nature. Absent from whole, unbroken cloves of garlic, allicin is the product of a biochemical reaction between two substances stored apart in tiny, adjoining compartments within each clove. The two are an enzyme, alliinase, and a normally inert chemical called alliin. When the clove is damaged, whether by soil parasites intending to eat the tender tissues, or by cooks making sauce, the membranes separating compartments are ruptured and rapid allicin production follows. The scientists realized that if doses of allicin could be repeatedly generated in this way at the site of the tumor, the highest concentration of the toxic molecules would be available for killing cancer cells.

To zero in on the targeted tumor, scientists took advantage of the fact that most types of cancer cells exhibit distinctive receptors on their surfaces. An antibody that is "programmed" to recognize the tumor's characteristic receptor is chemically bound to the enzyme, which is called alliinase. Injected into the bloodstream, the antibody seeks out these cells and lodges itself and its passenger enzyme on the tumor cells. The scientists then inject the second component, alliin, at intervals.

When it encounters the alliinase, the resulting reaction turns the normally inert alliin molecules into lethal allicin molecules, which penetrate and kill the tumor cells.

Thanks to the precise delivery system, healthy cells nearby remain intact. Using this method, the team succeeded in blocking the growth of gastric tumors in mice. The tumor-inhibiting effects were seen up to the end of the experimental period, long after the internally produced allicin was gone.

The scientists note that the method could work for most types of cancer, as long as a specific antibody can be customized to recognize receptors unique to the cancer cells.

The technique could prove invaluable for preventing metastasis following surgery, the researchers claim. "Even though doctors cannot detect where metastatic cells have migrated and lodged themselves," says Mirelman, "the antibody-alliinase-alliin combination should chase them down and destroy them anywhere in the body."

http://www.jpost.com/servlet/Satellite?pagename=JPost/JPArticle/ShowFull%26cid=1072844152757