A new xanthene was isolated from the methanolic extract of Desmostachya bipinnnata through repeated silica gel and octadecyl silica gel column chromatographies. Based on spectroscopic data including nuclear magnetic resonance, fast atom bombardment mass spectrometry, and infrared spectroscopy, chemical structure of the compound was determined to be 2,6-dihydroxy-7-methoxy-3H-xanthen-3-one. The compound exhibited inhibitions of signal transducer and activator of transcription 3-dependent luciferase activity in HCT-116 colon cancer cell line with $IC_{50}$ value of $5{mu}M$ and low-density lipoprotein-oxidation with $IC_{50}$ value of $27.2{mu}M$.