Wolfgang Steglich of Ludwig-Maximilians University in Munich and his colleagues extracted fruiting bodies from the common earthball mushroom Chalciporus piperatus. After a careful purification procedure, the researchers isolated a previously unknown pigment, which they dubbed sclerocitrin. Ripe earthballs produce an impressive amount of the color compound: from a kilogram of fungus, the team recovered 400 milligrams of the bright yellow chemical. After identifying sclerocitrin, the scientists also detected it in the stem bases of a second type of mushroom, the peppery bolete. In addition, the peppery bolete produces its own unique yellow pigment, which the team christened chalcitrin.
The researchers propose synthesis routes for the two chemicals that suggest the fungi produce them from a third, previously known pigment. The team next plans to test the novel chemicals for interesting biological activity.