Submitted to: American Society for Horticultural Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2001
Publication Date: N/A
Technical Abstract: St. John's Wort (Hypericum perforatum L.) is a medicinal plant which has been used since antiquity for its antidepressant properties, and is being studied as a potential alternative crop for Illinois growers. We are studying the effect of increasing CO2 concentrations (350, 1000, 3000, 10,000 and 30,000 uL CO2/L) on plant growth and concentrations of the putative active compounds, the naphthodianthrones hypericin and pseudohypericin. Purified naphthodianthrone standards were isolated using both open column and preparative HPLC procedures and identified by liquid chromatography-electrospray ionization-mass spectroscopy (LC-ESI-MS) and NMR. For quantitation of naphthodianthrones, plant material was exhaustively extracted with methanol, and separated using HPLC with UV detection at 590 nm. Hypericin and pseudohypericin concentrations were calculated from a standard curve of purified hypericin. While elevated CO2 levels had dramatic effects on plant growth, with growth continually increasing as CO2 concentrations increased, levels of naphthodianthrones were found to be highest when plants were grown at 1000 and 3000 uL CO2/L. Our data indicate that growing St. John's Wort plants under ultrahigh CO2 levels could substantially increase biomass without adversely affecting phytonutraceutical production, therefore allowing enhanced production of these desirable compounds.