Roquefortine C, a cyclopeptide derived from the diketopiperazine cyclo(Trp-dehydroHis), is a secondary metabolite produced by several Penicillium species, especially by Penicillium roqueforti, which is used as starter culture for blue cheese production. Although roquefortine C is frequently detected in the products, it obviously has an insignificant toxicity to humans after ingestion. However, intoxications in dogs and cattle have been reported. Its bacteriostatic activities against Gram-positive bacteria lead to Roquefortine C potential use in antibiotics, but its development as a drug has been stopped due to its neurotoxic effects in mice. Roquefortine C activates P-gp and inhibits P450-3A and other haemoproteins. Roquefortine C can serve as a sensitive biomarker for penitrem A intoxication.

Coprostanone is a metabolite of cholesterol. The conversion of cholesterol into coprostanol by intestinal microorganisms has been reported to occur by means of two different pathways. One pathway involves the intermediate formation of delta4-cholelestenone and coprostanone. In the other pathway, cholesterol is transformed into coprostanol by the direct reduction of the delta5 double bond. Coprostanone concentration is used as a fecal sterol biomarker in different investigations. For example, to determine of fecal sterols following a diet with and without plant sterols, to assess if faecal steroid excretion in humans is affected by calcium supplementation and other investigations.

Terreic acid is a metabolite with antibiotic properties produced by the fungus Aspergillus terreus. It was found, that terreic acid inactivated UDP-N-acetylglucosamine 1-carboxyvinyltransferase (MurA), a bacterial cell wall biosynthetic enzyme, by covalently attaching to Cys115. This compound also inhibits the catalytic activity of BTK (Bruton's tyrosine kinase) and the interaction of Btk with protein kinase C beta type (PKCβII) without affecting the activity of PKC.