Cinchotannic acid is a tannin contained in many cinchona barks, which by oxidation rapidly yields a dark-coloured phlobaphene[1] called red cinchonic,[2] cinchono-fulvic acid or cinchona red.[3]

References

  1. ^ Cinchona Bark (Cortex Cinchonae). Part 3
  2. ^ Cinchonaceae on chestofbooks.com
  3. ^ Quinine on www.1902encyclopedia.com