A traditional Chinese extract from the bark of the magnolia tree could give you fresh breath and kill off the oral microbes that cause halitosis. That's the claim by scientists at gum manufacturer Wm Wrigley Jr. They have found that the extract starts work within 30 minutes to stop bad breath and slow tooth decay.

Gum and mints are common enough products that consumers use to help freshen their breath. It is the activity of various bacteria on food particles in the mouth that produce smelly volatile sulfur compounds, including hydrogen sulfide, methyl mercaptan, and dimethyl sulfide, which are the main compounds responsible for bad breath. But, to kill off the bacteria that can cause bad breath and tooth decay in the first place requires regular brushing, flossing, and an antibacterial mouthwash. Antibacterial mouthwash is inconvenient to carry and use and can also cause staining of the teeth.

Now, Wrigley scientists Minmin Tian, Philip Urnezis, and Michael Greenberg of the Wrigley company labs in Chicago, Illinois, have investigated the microbicidal power of an extract of magnolia bark using saliva samples taken from volunteers following a regular meal. Two compounds, magnolol (5,5'-di-2-propenyl-(1,1'biphenyl)-2,2'-diol) and honokiol (3',5-di-2-propenyl-(1,1'-biphenyl)-2,4'diol) are the active ingredients in the extract, the researchers add.

Flavorless mints containing the extracts killed more than 61 percent of the microbes that cause bad breath within half an hour, the researchers say. Among these microbes are Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mutans. This compared well with the 3.6% kill rate for the same mints without the extract, the researchers say.

The team also found that the same extracts showed strong antibacterial activity against a group of bacteria known to cause dental caries, or cavities, including S. mutans. The researchers suggest that mints or chewing gum containing the extract may provide a "portable oral care supplement to toothpaste for those occasions where brushing is not possible."

J Agric Food Chem, 2007, 55, 9465-9469 http://dx.doi.org/10.1021/jf072122h