L-alloisoleucine (2S, 3R), a diastereomer of L-isoleucine (2S, 3S), is a normal constituent of human plasma. It was shown, that the plasma L-alloisoleucine above the cutoff value of 5 micromol/L is the most specific and most sensitive diagnostic marker for all forms of maple syrup urine disease (MSUD). The precise mechanism of L-alloisoleucine formation is unclear, but existed suggestions, that R-3-methyl-2-oxopentanoate is an immediate and inevitable byproduct of L-isoleucine transamination and that alloisoleucine is primarily formed via transamination of 3-methyl-2-oxopenanoate in vivo.

Urea nitrate is a powerful explosive. It has not found use as a legitimate explosive but is commonly used as an improvised explosive.

Hypoxanthine is a naturally occurring purine derivative and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the salvage pathway. Hypoxanthine is a necessary additive in the certain cell, bacteria, and parasite cultures as a substrate and nitrogen source. For example, it is commonly a required reagent in malaria parasite cultures, since Plasmodium falciparum requires a source of hypoxanthine for nucleic acid synthesis and energy metabolism.

Cystine is the oxidized dimer form of the amino acid cysteine. Cystine serves two biological functions, a site of redox reactions and a mechanical linkage that allows proteins to retain their 3-dimensional structure. It is common in many foods such as eggs, meat, dairy products, and whole grains as well as skin, horns and hair. Human hair and skin contain approximately 10–14% cystine by mass. Cysteine supplements are sometimes marketed as anti-aging products with claims of improved skin elasticity. Cysteine is more easily absorbed by the body than cystine, so most supplements contain cysteine rather than cystine. N-acetyl-cysteine (NAC) is better absorbed than other cysteine or cystine supplements.

Cholesterol is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. The high level of cholesterol in the blood is a marker of hypercholesterolemia, also called dyslipidemia. As a part of homeopathic product, it helps to support general liver and gallbladder health, and is used for temporary relief of symptoms related to adrenal glands such as fatigue and low energy. Cholesterol binds to and affects the gating of a number of ion channels such as the nicotinic acetylcholine receptor (nAChR) Inwardly-rectifying K+ channels (Kir); Transient receptor potential vanilloid 1 channels (TRPV1) and Large-conductance Ca2+-sensitive voltage-gated K+ channels (BK). It was shown the new mechanistic insights into the role of cholesterol in the regulation of nAChR, showing that cholesterol regulates the channels by two distinct mechanisms: stabilization of the channels in a resting state that depends on specific lipid-protein interactions and facilitation of the transitions between uncoupled and coupled states that depends on the hydrophobic thickness of the membrane

Phenylalanine is a biologically essential amino acid that acts as a precursor to tyrosine and the catecholamines (epinephrine, norepinephrine, dopamine, and tyramine), and is a constituent of many central nervous system neuropeptides. Normal dietary levels of phenylalanine are approximately 1-2 grams daily. Phenylalanine appears in two forms which are identical mirror images of each other: L-phenylalanine, a nutritional supplement, and D-phenylalanine, an effective painkiller and antidepressant due to its ability to inhibit the breakdown of enkephalins, the brain’s natural pain killers.

Tryptophan is alpha-aminoacid that is used in the biosynthesis of proteins. It is essential aminoacid in humans, meaning the body cannot synthesize and it must be obtained from the diet. Tryptophan is a precursor of serotonin, and as such is sold over the counter in many countries as a dietary supplement for use as an antidepressant, anxiolytic and sleep aid, however application of tryptophan in these indications is not approved by FDA.