Pseudane IX-d 4 (2-Nonylquinolin-4(1H)-one-d 4 ) is deuterium labeled Pseudane IX. Pseudane IX, a compound isolated from the leaves of Ruta angustifolia , has strong anti- HCV activity with an IC 50 value of 1.4 μg/mL. Pseudane IX reduces HCV RNA replication and viral protein synthesis levels.