Compound in cilantro may fight bacteria.

Researchers have identified a compound in cilantro, a key component of salsa and a variety of other dishes, that kills harmful Salmonella. It shows promise as a safe, natural additive that could help prevent foodborne illness.

Although previous studies by scientists showed that salsa has antibacterial activity, this is the first time that the researchers isolated any of the antibacterial compounds from it. The compound--dodecenal--was isolated from the fresh leaves of cilantro, or coriander, one of the main ingredients found in salsa. The compound also is found in the seeds of cilantro. Both the leaves and seeds contain about the same amount of dodecenal.

In laboratory tests, dodecenal was twice as potent as the commonly used medicinal antibiotic gentamicin at killing Salmonella. It is the only naturally occurring antibacterial that is more effective than gentamicin against Salmonella, the scientists claim. The investigators did not expect to find that dodecenal was such a potent antibiotic. Most natural antibacterial agents found in food generally have weak activity. The findings could lead to expanded use of dodecenal as an additive to prevent foodborne illness, perhaps as a protective coating on meats, or even as a general-purpose disinfectant to be used in cleaning and hand-washing.

In addition to dodecenal, about a dozen other antibiotic compounds were isolated from fresh cilantro that show some activity against a variety of harmful bacteria. Salsa likely contains even more antibacterial compounds that have not yet been identified, according to the scientists.

Dodecenal also shows promise in side-stepping the growing problem of antibiotic resistance. The researchers believe the compound works by destroying the cell membrane of bacteria, similar to the way soap kills bacteria. As the compound does not appear to interfere with any of the protein-manufacturing machinery of the cell, as occurs with many commercial antibiotics, bacteria are less likely to develop resistance to it.

The researchers do not plan to market dodecenal as a bacteria fighter or to test it further to see if it works in humans. But they acknowledge that their findings are attractive for companies that want to develop better ways to combat foodborne illness.

Further information. Isao Kubo, Department of Environmental Science, Policy and Management, University of California, Berkeley, 232A Hilgard Hall, Berkeley, CA 94720; phone: 510-643-6303; fax: 510-642-4034; email: ikubo@uclink.berkeley.edu.