A lichen metabolite and a derivative of lecanoric acid; inhibits the proliferation of human Hep-2 larynx carcinoma, MCF-7 breast cancer, and 786-0 kidney carcinoma cells, as well as B16-F10 murine melanoma and non-cancerous Vero cells (IC50s = 31.2, 70.3, 47.5, 64.8, and 28.1 μg/ml, respectively); toxic to brine shrimp (LC50 = 495 μM)