pterin

Pterins are a group of chemical compounds characterized by a specific bicyclic ring system known as pteridine. These compounds are significant in biology, particularly in coloration.12

Pterins are closely related to purines and were first identified and chemically isolated from the wings of butterflies, which is where they get their name. They are found as white, yellow, orange, or red granules within insect wing materials. While purines are often white crystals and can contribute to color patterns, pterins are directly involved in producing yellow, orange, and red hues in insects.3