Early results of a collaboration to investigate the impact of compounds from grapes could relate to oral bacteria indicate a role for polyphenols in preventing caries. The first results of a collaboration between researchers from the University of Rochester Medical Center and the New York, which was funded by the USDA, have been published in the Journal of Agriculture and Food Chemistry December 07.
The researchers investigated the make-up of polyphenols from different wine grape varieties, and how these interfere with Streptococcus mutans, (the bacteria that produces substances behind tooth decay), acid, and glucans (the building blocks of plaque).
The team was most interested in examining the impact of grape polyphenols on two capabilities of S. mutans that enable it to thrive in the human mouth. First, it secretes enzymes known as glucosyltransferases (GTFs) that produce sugary, glue-like substances (glucans) that firmly attach bacteria to tooth surfaces and form a tough barrier around bacterial colonies. Such barriers, called the extracellular polysaccharide (EPS) matrix, protect the colony against environmental assaults, and make them, in some cases, hundreds of times more resistant to antibiotics. These bacteria are known as biofilms, whether they occur on teeth or elsewhere in the body. Many Streptococci (strep) and Staphylococci (staph) cause resistant forms of meningitis, pneumonia, staph aureus, as well as infections on heart valves and around stents, by forming biofilms. GTFs are a main virulence factor responsible for S. mutans biofilm formation, but other pathogens use similar mechanisms to produce EPS matrix. The hope is that learning about one will suggest ways to interfere with many.
A second linked set of virulence factors for S. mutans are its abilities to secrete acid, and to survive in that acid. Having evolved to be “acid durable,” S. mutans can survive and out-compete other bacteria in the mouth. Better understanding of these mechanisms could also yield new ways to fight other biofilm related infections.
In the current study, researchers found that all polyphenol extracts inhibited two bacterial GTFs by as much as 85% (P<0.01)), a level of inhibition not previously observed in Koo’s lab. Cabernet Franc extracts were more effective GTF inhibitors, with Pinot noir a close second at concentrations that might be useful therapeutically. Grape polyphenols were also found to cause S. mutans to produce significantly less acid. This may be because they inhibit glycolysis, the process by which the bacteria turns sugar into energy also produces acid, researchers said. None of the extracts from any variety killed the bacteria outright. By targeting the ability of S. mutans to form EPS matrix, for example, therapeutic approaches to reducing the formation of biofilms could be precise and selective. Further chemical analysis will be needed to pinpoint which the most effective polythenol mix.
Hyun Koo, lead researcher stated that the aim is to isolate the key compounds in winemaking waste (such as quercetin and resveratrol) that disarm the bacteria, and to use these in consumer products, such as mouth rinse and the development of drugs to support oral health.
Source: Journal of Agriculture and Food Chemistry 2007 Dec 12;55(25):10200-7. Title: “Chemical characterization of red wine grape (Vitis vinifera and Vitis interspecific hybrids) and pomace phenolic extracts and their biological activity against Streptococcus mutans”.