The spelling of the word "epiguanin" is unique and not commonly used in everyday language. The correct pronunciation of this word is /ˌɛpiˈɡwɑnɪn/. The first syllable "epi" denotes "on" or "upon," and the second syllable "guanin" refers to one of the four basic building blocks of DNA. Thus, "epiguanin" could be interpreted as a molecular modification happening at the guanine base on DNA, which is essential for many cellular activities.
A purin body, C10H13N9O, found sometimes in the urine; it resembles guanin in its properties.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.