purpurin vs purpurine

purpurin

noun
  • A red anthraquinone dye, extracted from madder, that is used as a biological stain 

  • A protein of the lipocalin family 

  • A brownish or deep red decorative glass used in ancient times 

purpurine

noun
  • uroerythrin 

How often have the words purpurin and purpurine occurred in a corpus of books? (source: Google Ngram Viewer )