Ruta graveolens the isolation of the furanocoumarin chalepensin. The essential oil of "R. graveolens" contains two main constituents, undecan-2-one (46.8%) and nonan-2-one (18.8%). The bitter taste of its leaves led to rue being associated with the (etymologically unrelated) verb "rue" "to regret". Rue is well known for its symbolic meaning of regret and it has sometimes been called "herb-of-grace" in literary works. It is one of the flowers distributed by the mad Ophelia in William Shakespeare's "Hamlet" (IV.5): It was planted by the gardener in "Richard II" to mark the spot where the Queen wept upon hearing news of Richard's capture (III.4.104–105):
Hamlet (Thomas) triumph as Hamlet." The work was premiered at the Paris Opéra (Salle Le Peletier) on 9 March 1868. Among the noted singers in the original cast were Jean-Baptiste Faure as Hamlet and Christine Nilsson as Ophelia. The opera was staged, sung in Italian, at the Royal Italian Opera, Covent Garden (later the Royal Opera House, Covent Garden) in June 1869, with Nilsson as Ophelia and Charles Santley as Hamlet. "Hamlet" was Thomas's greatest success, along with "Mignon", and was further staged in Leipzig, Budapest, Brussels, Prague, New York City, Saint Petersburg, Berlin, and Vienna within five years of the Paris