Ph.D. Purdue University 1980
My research program centers on the plant natural products known as tannins, or polyphenolics. Tannins are found in many familiar plants--including food and beverage plants such as green & black tea; cranberries; strawberries; grapes and wine; and chocolate. The are also found in the leaves, bark and wood of familiar trees and herbs including oak, maple, willow, and fireweed. We are interested in the biological activities of polyphenolics and tannins, both in humans and in ecological systems.
In human health and nutrition, tannins are widely promoted as natural antioxidants which may provide protection from free radical damage associated with chronic diseases and aging. Phenolics are oxidized via one- or two-electron pathways, and are potent reducing agents. We use EPR to establish pathways of phenolic oxidation, to evaluate structures of radical intermediates during oxidation reactions, and to monitor kinetics of the reactions.
In the environment, tannins play a role in soil nutrient cycling. When plant material decays, tannins are released to enter soils and surface waters. Tannins may increase or decrease rates of carbon and nitrogen mobilization from dead plant tissue. Tannins also complex with many common metal ions--e.g. aluminum, zinc, copper, iron. Tannins may mobilize metals to make them more bioavailable or may chelate them in unavailable forms, influencing soil fertility and toxicity. In our studies of tannin-metal interactions in soil systems, EPR can probe both the phenolic component and the metal component of the system.
Our work on phenolics and metals in natural soil systems is funded by the USDA-ARS Appalachian Farming Systems Research Center in Beaver, WV. The photo shows our group relaxing with the scientists at the New River Gorge during a summer research meeting.