Medicinal plants get much-needed boost Investigator: Kim Lewis Tuesday Jul 9th, 2002 by Rabiya S. Tuma Traditional societies have relied on the curative powers of medicinal plants for centuries, but recent efforts by pharmaceutical companies and others to convert these resources into effective drugs have been lackluster. Researchers have discovered why such efforts often fail and have identified the key that promises to unlock the mystery of such therapies. There are over 50,000 botanically-derived compounds with antimicrobial characteristics, but many of them are relatively weak and have narrow specificity, says Kim Lewis, a professor of biology at Northwestern University. "In short they're all junk," he said. But why would plants with millions of years of evolution combat microbes with such weak ammunition? Logically, this didn't make sense, Lewis said. He therefore began looking for factors that might improve the compounds' antimicrobial power. Plant compounds are very effective at invading bacteria but are rapidly excreted out by bacterial multi-drug resistant (MDR) pumps. These MDRs are the same proteins that confer resistance to antibiotics in human pathogens. Inhibiting a bacterium's MDR may be the key to an antimicrobial's potency, Lewish hypothesized. Indeed, when he removed the MDR from Staphylococcus aureus, and then exposed the cells to berberine - a "weak" antimicrobial found in goldenseal, Oregon grape, barberry and other plants - the compound became incredibly toxic to the bacteria. The researchers then found a natural plant inhibitor of MDR, called 5'-methoxyhydnocarpin-D (5'-MHC). Although 5'-MHC has no antimicrobial activity on its own, berberine is much more effective when given in conjunction with the substance. "This is all snake oil and imagination or synergy," said Lewis. "Take one compound out and it doesn't work," but together they do. "This sets a precedent and now people are taking a second look at medicinal plants." Lewis' observation is "important" in developing antimicrobial therapies, commented one audience member. If MDR inhibitors can be also used to improve the efficacy of available drug therapies, he added, it would be very significant in the clinic, especially in tuberculosis, which is rapidly becoming a major public health problem. To assess whether plants use this approach widely, Lewis and his colleagues tested a panel of randomly chosen botanical compounds, in combination with synthetic MDR inhibitors, in a variety of bacterial species. Numerous compounds like rhein from rhubarb, and resveratrol, an antioxidant found in red wine, increase their antimicrobial efficacy several hundred-fold in combination with the inhibitors, the researchers found. The scientists have now also identified several more natural MDR inhibitors from geranium, artemisia, and other plants. WCP 2002 World Congress of Pharmacology BioMedNet.com Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.