tetrapyrroles

Natural pigments containing four pyrrole rings joined by one-carbon units linking position 2 of one pyrrole ring to position 5 of the next. Porphyrins are macrocyclic tetrapyrroles. E.g. bilin (a linear tetrapyrrole).
T06291
Source:
PAC, 1995, 67, 1307 (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1371
See also:
White Book, p. 279