Studies were made to find new skin whitening agents from stem parts of Zea mays. By the western blot test, the ethyl acetate extract of stem parts of Zea mays reduced the tyrosinase expression by 37%. The inhibitory melanogenesis was proved by the decrease of the mRNA transcription by 15% at the concentration of 100 mg/l. The skin whitening activity of the ethyl acetate extract was believed by the inhibition of tyrosinase. The extract also reduced MITF by inhibitory expression of MITF transcription factors. By the separation and isolation from the extract, a new skin whitening compound was identified as 4-hydroxybenzaldehyde. Synergistic effect of the extract with niacinamide reduced the melanin synthesis by 29%. In addition to intracellular melanin decrease by the extract, the synergistic effect was caused by the decrease of extracellular melanin content by niacinamide that inhibits melanosome transfers.
