Nature’s Antidepressant for Mild to Moderate Depression: Isolation and Spectral Characterization of Hyperforin from a Standardized Extract of St. John’s Wort (Hypericum perforatum)

Abstract

St. John’s wort (Hypericum perforatum) is a medicinal plant that has been used throughout history to treat depression. Its active constituent, hyperforin, inhibits neuronal uptake of monoamines and has been shown to be effective in the treatment of mild to moderate depression. However, hyperforin is highly unstable, sensitive to the effects of heat, light, oxygen, and lipophilic solvents. Despite this extensive degradation potential, this laboratory experiment has been optimized to allow upper-level undergraduate students studying nature’s medicines to isolate purified hyperforin from a standardized preparation by employing a number of techniques, such as purging mobile phases with nitrogen gas to remove oxygen and using amber sample tubes to protect purified fractions from light. Using these conditions, hyperforin is stable in a methanolic solution, and students take advantage of this factor during the isolation. Students acquire skills in the isolation and stabilization of a highly unstable molecule through use of flash column chromatography and carry out structure elucidation using a variety of spectroscopic methods. The experiment can be conducted over one three-hour laboratory period. A crossword puzzle to assess student learning following the experiment enables a comprehensive and engaging education, allowing appreciation of the journey of medicinal plant from bench to bedside.