Adenine was first discovered in 1885 by the German physiologist Albrecht Kossel. He isolated adenine from the pancreas of oxen and named it "adenine" derived from the Greek word "aden," meaning gland.

This image illustrates the chemical structure of a purine molecule, highlighting the numbering of the carbon and nitrogen atoms. The purine structure consists of a pyrimidine ring (positions 1 to 6) ...