Cilantro is a common ingredient in the popular Mexican dish salsa, itself the focus of various studies testing its supposed antibacterial properties, but this latest study is said to be the first to have isolated any of the antibacterial compounds from it.
The compound - dodecenal - was isolated from the fresh leaves of cilantro, one of the main ingredients found in salsa, along with tomatoes, onions and green chillies. The compound also is found in the seeds of cilantro, more commonly known as coriander. Both leaves and seeds contain about the same amount of dodecenal, but the leaves are used more abundantly in salsa.
In laboratory tests, dodecenal was twice as potent as the commonly used medicinal antibiotic gentamicin at killing Salmonella, a frequent and sometimes deadly cause of foodborne illness, the researchers said. It is the only naturally occurring antibacterial that is more effective than gentamicin against Salmonella, they claim.
"We were surprised that dodecenal was such a potent antibiotic," said study leader Isao Kubo, a chemist with the University of California, Berkeley. Most natural antibacterial agents found in food generally have weak activity.
"The study suggests that people should eat more salsa with their food, especially fresh salsa," he added.
In addition to dodecenal, about a dozen other antibiotic compounds were isolated from fresh cilantro which showed some activity against a variety of harmful bacteria, and Kubo suggested that salsa could contains even more antibacterial compounds that have not yet been identified.
The findings could lead to expanded use of dodecenal as a tasteless food additive to prevent foodborne illness, perhaps as a protective coating for meats in processing plants, or even as a general purpose disinfectant to be used in cleaning and hand washing, the researchers said.
But they also sounded a note of caution. "If you were eating a hot dog or hamburger, you would probably have to eat an equivalent weight of cilantro to have an optimal effect against food poisoning," Kubo said, underlining the need to ensure that meat products in particular are properly stored and prepared to ensure total safety.
The researchers said that their lab did not plan to market dodecenal as a bacteria fighter or test it further to see if it works in humans, but they did acknowledge that their findings were likely to prove attractive to the food industry and others wanting to develop better ways to combat foodborne illness.
The study appears in the 26 May issue of the Journal of Agricultural and Food Chemistry, a peer-reviewed publication of the American Chemical Society, the world's largest scientific society.