Indigo
　　Another name: reducing indigo
　　Index no. of dyes: C. I. Reducing blue 1 (73000)
　　Corresponding foreign trade name: INDIGO (Acna, Fran, ICI)
　　Molecular formula: C₁₆H₁₀O₂N₂
　　Molecular weight: 262.27
　　Chemical name: 3,3 - dioxbisindophenol
　　Chemical structural formula: