Identification of isopseudohypericin, a new phenanthroperylene quinone obtained by the alkaline treatment of pseudohypericin

At high pH, pseudohypericin from St. Johnʹs Wort (Hypericum perforatum) is converted into a single product which has been isolated. LC–MS analysis indicated that the molar mass of this product is identical to that of pseudohypericin. 1H and 13C NMR analysis indicated that the compound is a novel phenanthroperylene quinone which we have named isopseudohypericin; it is a cyclic ether which is an isomer of pseudohypericin.