3-Furoic acid is an organic acid regularly occurring in the urine of healthy individuals. 3-Furoic acid is also a compound found in honey and honeydew samples.

Esculin is found in barley.

5-Hydroxymethyluracil is an oxidation damage product derived from thymine or 5-methylcytosine. It is a product of thymine dioxygenase. Additional deamination products such as 5-hydroxymethyluracil are formed when cells are under oxidative stress that is induced either by oxidizing agents or by mitochondrial dysfunction.