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.

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.

Lysing is an essential basic amino-acid encoded by codone AAA and AAG, and used in the biosynthesis of proteins. The daily requirement for lysine is 38 mg/kg body weight. The most rich source of lysine is fish, beef, chicken. In a clinical study lysine supplements was found to be an effective for reduction of occurrence, severity and healing time for recurrent HSV infection, however Cochrane Review concluded that the evidence is insufficient. Lysine was investigated for improving anxiety, ameliorating angina prectoris. Lysine acetylsalicylate has been used to treat pain and to detoxify the body after heroin use. Lysine clonixinate has been used for its analgesic properties for the treatment of migraine headaches and other painful conditions. However, limited clinical trials exist for these conditions.

Tyrosine (L-form) is a non-essential amino acid, which is primarily required for the protein synthesis. This amino acid is the precursor of dopamine, norepinephrine, and epinephrine; therefore the lower concentration of tyrosine could be a peripheral marker of the hyperdopaminergic condition hypothesized to explain psychosis. Tyrosine supplements can improve cognition, increase energy, reduce anxiety, reduce depression, reduce levels of pain.

N-Acetyltyrosine is an acetylated derivative of the amino acid L-tyrosine. Ordinary L-tyrosine is less stable and also less soluble in water, which may result in reduced bioavailability. Acetylation enhances the solubility and stability of certain amino acids. N-Acetyltyrosine is commonly used in place of tyrosine in parenteral nutrition. It converts to tyrosine and then can be used in neurotransmitter treatment as a precursor of cathecholamine. N-Acetyltyrosine supports brain function by supporting the synthesis of the catecholamines norepinephrine and dopamine (neurotransmitters). N-Acetyltyrosine supplements are used to improve memory and cognitive performance in humans while they are experiencing psychological stress.

Buserelin is a synthetic peptide analog of the luteinizing hormone-releasing hormone (LHRH) agonist, which stimulates the pituitary gland's gonadotrophin-releasing hormone receptor (GnRHR). Buserelin is used for palliative treatment of prostate cancer, and for treatment of endometriosis. Buserelin is also used for infertility treatment to prepare the pituitary gland before starting treatment with gonadotrophins (FSH and LH) to artificially stimulate ovulation.

Masitinib is a new orally administered tyrosine kinase inhibitor that targets mast cells and macrophages, important cells for immunity, through inhibiting a limited number of kinases. Based on its unique mechanism of action, masitinib can be developed in a large number of conditions in oncology, in inflammatory diseases, and in certain diseases of the central nervous system. In oncology due to its immunotherapy effect, masitinib can have an effect on survival, alone or in combination with chemotherapy. Through its activity on mast cells and consequently the inhibition of the activation of the inflammatory process, masitinib can have an effect on the symptoms associated with some inflammatory and central nervous system diseases and the degeneration of these diseases. AB Science is developing masitinib in multiple sclerosis and alzheimer's disease. Masitinib targets kinases, including c-Kit, PDGFR, and Lyn. It is used in the treatment of mast cell tumors in animals, specifically dogs. Since its introduction in November 2008 it has been distributed under the commercial name Masivet. It has been available in Europe since the second part of 2009. In the USA it is distributed under the name Kinavet.

Olmutinib is a novel third-generation epidermal growth factor receptor (EGFR) mutation-specific tyrosine kinase inhibitor, used in the treatment of T790M mutation positive non-small cell lung cancer. Olmutinib covalently binds a cysteine residue near the kinase domain of mutant EGFRs to prevent phosphorylation of the receptor. EGFRs are frequently over-expressed in lung cancer and contribute to activation of the phosphoinositide 3-kinase and mitogen-activated protein kinase pathways which both promote cell survival and proliferation. By inhibiting EGFR activation, Olmutinib attenuates the activation of these tumor-promoting pathways. In the first phase I/II clinical study of Osimertinib, 800 mg/ day was chosen as the dose for subsequent studies, and the dose-limiting toxicity and maximum tolerated dose was not reached. Olmutinib received breakthrough therapy designation in the United States in December 2015 and was approved for use in Korea in May 2016.

Diiodotyrosine (DIT) is a regulatory ligand for thyroid peroxidase, enzyme, which is involved in the production of thyroxine (T4) and triiodothyronine (T3), the thyroid hormones. Diiodotyrosine was proposed to be a new marker of leukocyte phagocytic activity in sepsis and severe infections.