Pastaron (Urea) is a waste product of many living organisms, and is the major organic component of human urine. It is a very important starting material in a number of chemical syntheses, and is used on an industrial scale for the manufacture of fertilizers, pharmaceuticals, and resins. Urea is an osmotic diuretic similar to mannitol but more irritant. Applied topically, urea promotes hydration of keratin and mild keratolysis in dry skin. It increases water uptake by the stratum corneum and has an antipruritic effect. Pastaron is used to soften rough or dry skin caused by skin conditions such as eczema, psoriasis, keratosis, and others.

Melatonin (5-methoxy N-acetyltryptamine) is a hormone synthesized and released from the pineal gland at night, which acts on specific high affinity G-protein coupled receptors to regulate various aspects of physiology and behaviour, including circadian and seasonal responses, and some retinal, cardiovascular and immunological functions. Melatonin is also made synthetically and available without a prescription as an over-the-counter (OTC) dietary supplement in the U.S. Melatonin supplementation has many uses, however, it has been widely studied for treatment of jet lag and sleep disorders. Parents may consider using melatonin to help their child who has a trouble falling asleep. A medical professional should always evaluate insomnia or other sleeping disorders in children. Additionally, melatonin has been shown to protect against oxidative stress in various, highly divergent experimental systems. There are many reasons for its remarkable protective potential. In mammals, melatonin binds to a number of receptor subtypes including high-affinity (MT1 and MT2) and low-affinity (MT3, nuclear orphan receptors) binding sites, which are distributed throughout the central nervous system and periphery.

Deoxyguanosine is a nucleoside consisting of the base guanine and the sugar deoxyribose. It is like guanosine, but with one oxygen atom removed. It is a nucleoside component of DNA. Deoxyguanosine can be converted to 8-hydroxy-deoxyguanosine (8-OHdG) due to hydroxyl radical attack at the C8 of guanine. 8-OHdG is a sensitive marker of the DNA damage This damage, if left unrepaired, has been proposed to contribute to mutagenicity and cancer promotion. Deoxyguanosine has long been recognized as a potent cytotoxic agent to cultured mammalian cells. This toxicity or inhibition of DNA synthesis by deoxyguanosine appears to be mediated by deoxyguanosine triphosphate-mediated inhibition of the enzyme ribonucleotide reductase. Purine nucleoside phosphorylase deficiency is thought to cause T-lymphocyte depletion by accumulation of deoxyguanosine and deoxyguanosine triphosphate, resulting in feedback inhibition of ribonucleotide reductase and hence DNA synthesis. Deoxyguanosine nucleoside analogs are potent antiviral agents.

2′-Deoxyadenosine, a pair of deoxythymidine (T) in double-stranded DNA, is a substrate of adenosine deaminase. In case of absence of this enzyme, 2′-deoxyadenosine accumulates in T lymphocytes and kills these cells resulting in a genetic disorder known as adenosine deaminase severe combined immunodeficiency disease (ADA-SCID).

Thymidine is a water-soluble pyrimidine deoxynucleoside and potent thymidine kinase substrate. Thymidine is known to be converted to dTTP and utilized for DNA synthesis. It is also known that thymidine is converted by catabolic enzymes to several end products. Excess thymidine results in high levels of dTTP, which exerts a regulatory feedback inhibition in the nucleotide biosynthesis pathways leading to DNA synthesis. This property of thymidine is used when it is given in high doses to patients with solid tumors. Thymidine is being tested in Phase II of clinical trials for the treatment of cancer and 5'-Nucleotidase Syndrome.

Pyridoxal is a pyridinecarbaldehyde and a form of vitamin B 6 which is converted to pyridoxal phosphate. Pyridoxal 5'-phosphate is involved in a wide range of biochemical reactions, including the metabolism of amino acids and glycogen, the synthesis of nucleic acids, hemoglobin, sphingomyelin, and other sphingolipids, and the synthesis of the neurotransmitters serotonin, dopamine, norepinephrine and gamma-aminobutyric acid (GABA). Pyridoxal is one of the natural forms available of vitamin B6, therefore, it is used for nutritional supplementation and for treating dietary shortage or imbalances. Some medically relevant bacteria, such as those in the genera Granulicatella and Abiotrophia, require pyridoxal for growth. This nutritional requirement can lead to the culture phenomenon of satellite growth. In in vitro culture, these pyridoxal-dependent bacteria may only grow in areas surrounding colonies of bacteria from other genera ("satellitism") that are capable of producing pyridoxal.

Beta-alanine is an endogenous agonist of glycine receptor, which is used a supplementation among competitive athletes participating in a range of different sports. Beta-alanine has been shown to enhance muscular endurance and its supplementation appears to be most effective for exercise tasks that rely heavily on ATP synthesis from anaerobic glycolysis.

Bilirubin is an orange-yellow pigment made during the normal breakdown of red blood cells. Bilirubin passes through the liver and is excreted out of the body. Occasionally, higher bilirubin levels may indicate an increased rate of destruction of red blood cells (hemolysis). A high level of bilirubin in the blood is called hyperbilirubinemia. High bilirubin levels can cause jaundice. Jaundice makes the skin and the whites of the eyes appear yellow, due to the brown and yellow bilirubin in the blood. Phototherapy for neonatal is one of the treatment methods against hyperbilirubinemia. Light absorption by bilirubin in the skin transforms the native Z,Z-bilirubin to conformational photoisomers Z,E-bilirubin and E,Z-bilirubin and structural photoisomers E,Z-lumirubin and E,E-lumirubin. Formation and excretion of Z,E-bilirubin and E,Z-lumirubin are both important routes of elimination of bilirubin through bile and urine, although the precise contributions of the various photoisomers to the overall elimination of bilirubin are still unknown.

SERINE, D- (D-serine) is a non-essential amino acid occurring in natural form as the L-isomer. It is synthesized from glycine or threonine. It is involved in the biosynthesis of purines, pyrimidines and other amino acids. A considerable level of D-serine was discovered, surprisingly, in the mammalian brain in the early 1990s. Since then, D-serine has been considered to be a co-agonist of glutamate at the glycine site of NMDA receptors. D-serine plays an important role in the central nervous system as an endogenous ligand for the glycine site of glutamate N-Methyl-D-Aspartate (NMDA) receptors. D-serine is synthetized by racemization of L-serine in most neural and non-neural cells, and modulates a variety of physiological functions in mammals. D-Serine synthesis is attributed to Serine Racemase (SR), which catalyses the synthesis of D-serine from L-serine. D-serine may play a role in the pathophysiology of neuropsychiatric disorders, such as schizophrenia, which may be linked to NMDA receptor hypo-function. Studies in genetic and pharmacological animal models with decreased D-serine levels have shown that these animals displayed behavioural abnormalities similar to those seen in schizophrenia. Moreover, exogenous administration of D-serine and related compounds improved several phenotypes relevant to schizophrenia, which could have positive clinical implications in humans. The results of a clinical trial in Taiwanese schizophrenic patients who received D-serine as adjuvant treatment indicated that those patients who received D-serine treatment, improved positive, negative and cognitive symptoms seen in schizophrenia. In addition, this clinical trial showed that D-serine did not worsen side effects from other antipsychotics, which may be due to its selective action at the NMDA-glycine site. Therefore, D-serine could be considered as a therapeutic approach for schizophrenia, which is different from the dopaminergic approach. It has also been shown that exogenous d-serine administration can suppress appetite and alter food preference. Thus NMDA receptor and its co-agonist d-seine participate in the control of appetite and food preference, which can be used to suppress obesity. D-serine has been shown to have cognitive-enhancing properties in different brain disorders and in age-related cognitive decline. From a clinical perspective, it is important to highlight that in a recent double-blind placebo-controlled cross-over study our group observed that an acute oral administration of 30 mg/kg of d-serine improved spatial learning and problem solving. D-serine may be especially useful for depression because of its acute and chronic antidepressant effects,