New method softens up germs

Oct. 3, 2001

by Madeline Fisher

Found in everything from toothpastes, soaps and cosmetics, to sponges, cutting boards and baby toys, antibacterial agents are seemingly as ubiquitous these days as the microbes they target. But as the use of antibacterial agents in everyday items has soared, so have fears about the widespread emergence of resistant bacteria.

Now, Eric Johnson and Byron Brehm-Stecher, scientists with the Food Research Institute, have devised a promising way to keep microbes vulnerable to germ-killers, using plant-derived compounds called sesquiterpenoids.

The researchers found that when teamed with small amounts of sesquiterpenoids, several antibiotics and other antibacterial agents became much better at killing bacteria, including some pathogenic strains. Their discovery could pave the way for new antibacterial formulations that would be effective at much lower doses in consumer products.

Sesquiterpenoids could also extend the life of antibiotics and antiseptics that might otherwise be vanquished by resistant microbes - a concern that keeps the pharmaceutical, food and sanitation industries constantly searching for new germ-killing agents.

Sesquiterpenoids naturally contribute to the aromas and flavors of herbs, spices and flowers and are already widely used in perfumes and as flavorants. Reports suggesting that drinkers of green tea have less tooth decay are what led the researchers to begin their studies with nerolidol - a sesquiterpenoid that helps give green tea it's distinctive taste.

The plant compounds likely make bacterial cells more susceptible to antibiotics by incorporating themselves into cell membranes, Brehm-Stecher explains. The presence of the sesquiterpenoids damages the membranes, making them unnaturally porous and allowing antibiotics to flood the cells.

Because their tastes and smells are naturally pleasing to people, the microbe-sensitizing compounds would be especially suited for use with preservative agents in cosmetics or with antibacterials in fruit and vegetable washes, Brehm-Stecher says.

A patent for this technology has been applied for by the Wisconsin Alumni Research Foundation, a non-profit organization that manages the intellectual property of the UW-Madison.