A Comparison of Phytochemicals Present in Midwestern Medicinal Plant Extracts

Abstract

Plants consumed as medicines are thought to exert their physiological effects in part through the activity of their secondary metabolites, which include molecules with antioxidant activities. In this study, the concentrations of total phenolic, flavonoid, and anthocyanin compounds of eight medicinal plant extracts collected from Earlham College in Richmond, Indiana were examined. The collected data showed a wide range of variation in the concentration of antioxidant compounds in the eight examined plant extracts; the locally-collected gingko samples had the highest total phenolic content and plantain had the highest flavonoid content, while the black raspberry and mulberry samples had by far the highest anthocyanin content. In addition to describing the chemical composition of medicinal plants valued in the Midwestern United States, we compared different sources (Earlham College vs. purchased) and preparations (acetone vs. hot water extraction) of gingko leaves and compared the chemical composition of extracts that underwent an unintended additional freeze-thaw cycle. Gingko leaf extracts have the highest phenolic content of all extracts examined, and the purchased gingko teas and powder had higher levels of phenolic contents than all the locally collected, acetone extracts. Additionally, among the Midwestern species tested, no significant changes were observed in the concentrations of compounds measured in the extracts that underwent an additional freeze-thaw cycle. This study not only compares the phenolic compound composition of medicinal plant extracts but also provides pertinent information on the collection, preparation and storage of plant extracts to conserve these phenolic compounds.