Exposure to light is detrimental to the stability of aqueous solutions of psilocybin, and will cause it to rapidly oxidize—an important consideration when using it as an analytical standard. Osamu Shirota and colleagues reported a method for the large-scale synthesis of psilocybin without chromatographic purification in 2003. Starting with 4-hydroxyindole, they generated psilocybin from psilocin in 85% yield, a marked improvement over yields reported from previous syntheses. Purified psilocybin is a white, needle-like crystalline powder with a melting point between , and a slightly ammonia-like taste.