The 17-ketosteroid epiandrosterone is a metabolite of testosterone precursor dehydroepiandrosterone (DHEA). Epiandrosterone have been considered to be merely inactive end product of DHEA, but may in fact be physiological effectors in their own right. It is formed in peripheral tissues, from which it is released into the circulation and is ultimately excreted in the urine. Epiandrosterone is only a weak androgen, but it is widely recognized to inhibit the pentose phosphate pathway and to decrease intracellular NADPH levels. Epiandrosterone may act as a L-type Ca2+ channel antagonist. Epiandrosterone mainly transformed into 17beta-hydroxylated derivatives, 7- or 16alpha-hydroxylated metabolites under NAD(P)H conditions, and 5alpha-androstane-3,17-dione under NAD(P)+ conditions. Epiandrosterone is used as an anabolic agent (dietary supplement, a precursor to dihydrotestosterone) to increase strength, muscle hardness and also improves libido.

Biopterin (also known as L-erythro-biopterin or 6-Biopterin) is an oxidation product of tetrahydrobiopterin. Bioptrrin is an endogenous enzyme cofactor and its accumulation serves as markers of Parkinson's disease, Hyperphenylalaninemia and in addition, it can serve as a non-invasive biomarker for cancer.

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