Just that indole's the major decomposition product of "indolic" compounds. It's part of the glue that holds turds together. Alkaline pyrolysis of tryptophan-containing compounds gives indole. Hot zinc dust is an extreme reduction environment. Indole compounds substituted at the preferred 3-position, have these substituents much more labile than corresponding chains on a benzene ring. So in this case my guess is, that before taking off a hydroxyl group at the 4-, 5-, or 6-position, zinc dust distillation would give you back the corresponding indole, still perhaps with a 4-, 5-, or 6-hydroxyl, but without your labor-intensive dimethylaminoethyl moiety on 3-.
a half a pints a half a pound a half a world a half a round
