A prodrug form of rhein; inhibits RANKL- and IL-1β-induced differentiation of RAW 264.7 cells into osteoclasts at 20 UG/ml; reduces levels of ICE, IL-1β, and IL-18 in the superficial zone of human osteoarthritic cartilage explants at 20 UG/ml; decreases carrageenan-, dextran-, or zymosan-induced paw edema in rats at 100 mg/kg