of many mushrooms that can regularly be found fruiting on ancient timber wharves. The fruit bodies are used as a primary food source by the red squirrel Sciurus vulgaris, and have a higher protein content than the other mushrooms typically consumed by this species. Decaying fruit bodies are also used as a food source by fruit flies of the genus Drosophila. Chemistry The fruit bodies contain unique chemical compounds that are derived from phenylpropanoids. The compounds, named squarrosidine and pinillidine, inhibit the enzyme xanthine oxidase. Xanthine oxidase catalyzes the crystallization of uric acid in the joints, a main cause of gouty arthritis, and inhibitors of this enzyme are being used clinically to reduce this side effect. The natural function of these compounds may be to quench reactive oxygen species produced by plants as a defensive response to fungal infection. See also List of Pholiota species References Strophariaceae Fungi described in 1770 Fungi of Europe Fungi of North America