Rucinol is derived from resorcinol and is an inhibitor of the enzymes tyrosinase and tyrosinase-related proetin-1 (TRP-1), two important enzymes in melanin synthesis. It is one of the less investigated agents for treating melasma. In one study of 32 patients rucinol serum 0.3% was compared with the corresponding vehicle for treating melasma. After 12 weeks of twice daily application, the rucinol treated side showed a decrease in pigmentation compared to the control side. Rucinol-containing products are not widely available, but more are expected to be developed in the future.