Salsoline is a metabolite of dopamine and is highly prevalent in the urine and cerebrospinal fluid of alcoholics at the time of intoxication and for several days after. Salsoline and related compounds bind to the Type A Mono-amine Oxidase inducing neuronal cell death. At one time salsoline was thought to be a biomarker for Parkinson's disease. However, it was later shown that treatment regimes result in an increased endogenous concentration of salsoline and related compounds.

5'-Methylthioadenosine, also known as methylthioadenosine or MTA, is a naturally occurring sulfur-containing nucleoside present in all mammalian tissues. MTA is produced from S-adenosylmethionine mainly through the polyamine biosynthetic pathway, where it behaves as a powerful inhibitory product. This compound is metabolized solely by 5'-methylthioadenosine phosphorylase (MTAP), to yield 5-methylthioribose-1-phosphate and adenine, a crucial step in the methionine and purine salvage pathways, respectively. MTA has been shown to influence numerous critical responses of the cell including regulation of gene expression, proliferation, differentiation and apoptosis. Also was shown that MTA inhibits melanoma cell proliferation and in vivo tumor growth particularly in BRAF mutant melanoma cells. These data reveal a naturally occurring drug potentially useful for melanoma treatment.

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.