ScienceDaily (Aug. 30, 2001) — Dentists from the University of Rochester Medical Center and food scientists at State University of Campinas in Brazil have discovered that a substance that Brazilian honeybees make to protect their hives might prove to be a potent anti-cavity agent.
The substance is propolis, a sticky material like glue that bees make to hold their hives together. Bees create the brew by collecting secretions from trees and other plants, carrying them back to the hive, chewing up the materials, then spitting the concoction out and mixing it with beeswax. In a hive, the substance is used to seal holes, keep the hive clean, and even to embalm dead insects.
In laboratory tests, the most potent version of the substance, from southern Brazil, cut the cavity rate in rats by about 60 percent, and nearly stopped the activity of a key enzyme that forms dental plaque. Dentists say that since rats get cavities the same way as humans do, and the same substances that prevent cavities in the animals also prevent cavities in humans, they’re enthusiastic about the potential of the substance to prevent cavities in people. Dentists hope to test the substance on human volunteers.
The link between hive and health was first noted by Michel Hyun Koo, D.D.S., Ph.D., who earned his dental degree in Brazil and then decided to study food biochemistry. Thanks in part to active honeybee research across campus at State University of Campinas, Koo began studying propolis and soon was traveling around Brazil collecting the material from hives, using a device like a putty knife to scrape the dark yellow or brown, caulk-like substance from hives. His first experience left him barely able to walk, as he received about two dozen stings around his ankles from angry bees because his black socks triggered the bees’ defensive behavior.
Brushing the pain aside, Koo persisted, focusing on the cavity-fighting potential of propolis as he earned his master’s degree in food science and his doctorate in oral biology in Brazil. Then he came to the Center for Oral Biology at the University of Rochester to try to pinpoint the most effective cavity-fighting substances in propolis. Koo was recognized this summer by the International Association for Dental Research, which awarded him its Research in Prevention Award for research in North America at its annual meeting; he received the same award, for research in South America, in 1998 for his earlier work.
“The potential with these natural products is enormous. The bees are doing a great work for human health, by facilitating the identification of compounds with applicability to dental science,” says Koo.
The team isn’t the first to note the health effects of propolis. Human use of propolis dates back to at least 300 B.C., and today there are creams, lotions, and even chewing gum that contain propolis and tout its anti-bacterial, anti-inflammatory, and anti-oxidant properties. In recent times people have claimed that the substance is useful in wound healing, tissue regeneration, and for treating burns, psoriasis, and herpes. Propolis is used as a food additive in Japan, and demand is strong in Europe too; in the United States, Koo says, there has been little demand, though lately he has seen propolis popping up on store shelves, as anti-oxidant capsules or as a solution to treat cuts.
But not all propolis is created equal; the quality and make-up of propolis varies dramatically, depending largely on the plants and trees of the region where honeybees do their work. Koo analyzed more than 2,500 propolis samples from Brazil alone and found 12 different chemical compositions.
“There is a huge variability in terms of chemical composition, depending on the plant ecology of the specific regions where bees collect this material. Just because there’s propolis in toothpaste doesn’t mean it’s useful,” says Koo, noting that there are a few mouth washes and toothpastes that contain propolis. “There’s a huge variety of propolis out there, and much of it is useless against cavities.” That’s why Koo’s colleagues in Brazil are working with beekeepers there to create international standards for propolis.
During the past two years Koo has spent thousands of hours in his Rochester laboratory, working with dental research William Bowen, D.D.S., Ph.D., to figure out exactly which of the more than 100 compounds in propolis are responsible for its cavity-preventing properties. They have found two substances, both present in the potent propolis made by bees in southern Brazil, that seem especially protective. The University of Rochester and State University of Campinas have filed for patents on the compounds, which target both the bacteria that form cavities as well as the specific enzymes that take part in the process.
Dentists are most excited by the action of one of the substances against glucosyltransferase (GTF) enzymes, which play an important role in the buildup of plaque on teeth. The enzymes create molecules called glucans to construct a biofilm, and, like masons at a construction site, they use the glucans like bricks to form a formidable structure that serves as a sort of safe harbor for bacteria to collect, latch onto teeth, and secrete acid that eats away at our enamel. This whole assembly, a biofilm not much different than the slime on a boat hull, is what we call plaque, says Bowen.
“Once this mesh of sugars and bacteria forms, it becomes easier for other bacteria to stick to it. More bacteria join in, and the plaque becomes one big acid factory. It’s like an acid sponge sticking to your tooth’s surface,” Bowen says.
Knocking out the enzymes that build plaque is a key to oral health, Bowen says. Within seconds after brushing your teeth or having them cleaned professionally, GTF enzymes mount an assault on a tooth, creating a biofilm that other bacteria latch onto. Even the nearly one liter of saliva that our body sends washing over our teeth every day isn’t enough to neutralize plaque.
Koo and Bowen found that one of the substances they isolated is the best inhibitor of GTFs that scientists have ever seen. The substance is especially effective at blocking the enzyme that the most common pathogen in our mouth, Streptococcus mutans, uses to build plaque, and it also blocks a particular GTF enzyme that no other compound is known to inhibit. The substance blocked up to 95 percent of the action of GTFs in the test tube and about 60 to 70 percent on tooth-like surfaces, accounting for its effectiveness at reducing cavities in animals.
In addition to Koo and Bowen, the research team includes dental researcher Anne Vacca Smith and research associate Sylvia Pearson of Rochester, dental researchers Pedro L. Rosalen and Jaime A. Cury of State University of Campinas in Brazil, and food scientist Yong K. Park of State University of Campinas. The work was funded by the National Institute of Dental and Cranio-Facial Research and the Brazilian Government Agency.
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