The invention discloses the use of sappanone-A in inhibiting melanogenesis. The sappanone-A can be made by using Synthesis Technologies well known to chemists, or produced by using separation and purification technology from natural sources of plant material, such as Caesalpinia genus, preferably at least one of the following: Caesalpinia sappan Linn., Caesalpinia pulcherrima, and Caesalpinia japonica, and suitable for using in forms of injection, dispersion, sterile powder or external preparation. This pharmaceuticals can further include pharmaceutically acceptable carrier such as solvent, buffer, emulsifier, suspending agent, decomposer, disintegrating agent, dispersing agent, binding agent, excipient, stabilizing agent, chelating agent, diluent, gelling agent, preservative, wetting agent, lubricant, absorption delaying agent, and liposome.本發明揭示蘇木酮A可被用來抑制黑色素生成。