Hypericin is an active ingredient in the medical herb St. John’s Wort (SJW). Hypericin displays antineoplastic activity as well as antibiotic and antiviral activities. Hypericin has antidepressive activity through inhibiting monoamine oxidase enzyme. It also inhibits RANKL-mediated osteoclastogenesis via affecting ERK signaling in vitro and suppresses wear particle-induced osteolysis in vivo.