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Collaborative research between Dr. Chad Scholes (Biology) and Dr. James Chapman (Chemistry).

Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. The term tannin refers to the source of tannins used in tanning animal hides into leather; however, the term is applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with proteins and other macromolecules. Tannins have molecular weights ranging from 500 to over 20,000. Tannins are usually divided into hydrolyzable tannins and condensed tannins (proanthocyanidins). While hydrolyzable tannins and most condensed tannins are water soluble, some very large condensed tannins are insoluble. The role of plant tannins in nature is believed to be multi-faceted with implications in plant-predator defense mechanisms and the inhibition of plant tissue decomposition presumably through antimicrobial or anti-nematodial activity. Even though tannins exist in almost all of a plant’s tissues, these molecules seem to do so without involvement in a plant’s physiological processes. Several types of potential secondary benefits attributed to tannins have been reported and include anti-thelmintic properties in grazing animals, anti-oxidant activity and cytotoxic effects against cancer cells. However, the chemical or biochemical role of the tannins that has been proposed has been typically based on the crude extracts without a thorough investigation of the individual tannins. There are a few examples where work has been carried out on isolated tannins, but the molecules constitute such an enormous class of compounds with tremendous structural diversity that much work is still to be done in this regard.

Acorns Ellagitannin Structure

Collaborative research between Dr. James Chapman (Chemistry), Dr. Kelly Kindscher (University of Kansas), Dr. Richard C. D. Brown (Southhampton University, Southampton, UK), and Scott Niemann (CSS Analytical Company).

Prairie plants of the Great Plains have historically been used as medicines by North American Indian tribes, settlers, and physicians since the early 19th century. Ethnobotanical studies have documented over 200 of these plants, which have been used for medicinal purposes. In an attempt to uncover the relationship between the constituents and the purported medicinal properties, we have been working collaboratively with Dr. Kelly Kindscher of the Kansas Biological Survey and Scott Niemann of CSS Analytical Company. Dr. Kindscher has been kind enough to identify plants of interest and gather the materials for analysis. Scott has allowed us to utilize some of his instrumentation for the characterization of the plant extracts.

This ongoing project is being carried out at Rockhurst University to determine the identities of the chemical constituents responsible for the purported medicinal activities of several prairie plants. The native prairie plants that were selected for this study were done so with the cooperation of an ethnobotanist from the University of Kansas, Dr. Kelly Kindscher. Dr. Kindscher selected the plants for investigation because of the long history of usage by Native American Indian tribes.

Collaborative research between Dr. Chad Scholes (Biology), Dr. Mindy Walker (Biology) and Dr. James Chapman (Chemistry).

Anthocyanins are water soluble vacuolar flavonoid pigments that reflect the red to blue range of the visible spectrum, depending on the pH of the surrounding solution. They are found exclusively in the plant kingdom, and have been observed to occur in all tissues of higher plants, providing color in everything from fruits to autumn leaves. In flowers, anthocyanins help attract pollinators, and in fruits, the colorful skins help to attract animals (which will eat the fruits and disperse the seeds). In photosynthetic tissues (such as leaves), anthocyanins have been shown to act as a "sunscreen", protecting cells from photo-damage by absorbing UV and blue-green light during periods of high light stress (as occurs when plants are exposed to high light in combination with drought or cold temperatures). Anthocyanins also act as powerful antioxidants helping to protect the plant from radicals formed by UV light and during metabolic processes. The anthocyanins themselves are subdivided into the sugar-free anthocyanin aglycones and the anthocyanin glycosides. As of 2003 more than 400 anthocyanins had been reported, while more recent literature (early 2006), puts the number at more than 550 different anthocyanins. The characteristic red and purple color of many petunia flowers is due to the presence of anthocyanins, which more specifically are a large family of glycosylated polyhydroxy and polymethoxy derivatives of flavylium salts. Initially, anthocyanins were characterized through the use of paper chromatography. This gave way to the utilization of reversed-phase HPLC coupled with UV-Vis detection. However, discrepancies between many studies using this method exist because comparing retention times and UV-visible spectra alone is frequently insufficient for differentiating pigments with similar isomeric structures. In an effort to remedy its shortcomings, researchers have combined this methodology with electrospray ionization mass spectrometry (ESI-MS). ESI, a highly sensitive, mild, ionization technique has since proven to be a very powerful tool for anthocyanin characterization. Extensive work has been conducted to elucidate not only what anthocyanins are present in nature but also, which anthocyanins are characteristic of various flora. The purpose of this study is the characterization and conclusive identification of anthocyanins and betacyanins present in several varieties of flower blooms.