Quinolinic acid is an endogenous N-methyl-D-aspartate receptor agonist synthesized from L-tryptophan via the kynurenine pathway and thereby has the potential of mediating N-methyl-D-aspartate neuronal damage and dysfunction. Elevated cerebrospinal fluid levels of quinolinic acid are correlated with the severity of neuropsychological deficits in patients who have AIDS. It can act as an endogenous brain excitotoxin when released by activated macrophages. Quinolinic acid is being used as a research tool to examine the role of excitotoxicity in neuronal degeneration associated with a number of neurological diseases (Alzheimer's disease, Huntington's disease, Parkinson's disease) which involve selective neurotransmitter deficits.

Pentosalen (Imperatorin) is a bioactive furanocoumarin and a phytochemical that has been isolated from Urena lobata L. (Malvaceae), Angelica archangelica, etc. Pentosalen has a wide range of potent pharmacological activities, including antibacterial, antitumor, anticonvulsant, acute neurotoxic effects and abirritation. Pentosalen possesses notable anti-inflammatory activity by inhibiting the production of nitric oxide (NO) and prostaglandin E2 (PGE2), and decreasing the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX) 2 and microsomal prostaglandin E synthase. Pentosalen selectively targets gastric cancer cells without causing much damage to normal cells. Pentosalen was identified from a Bioactive Molecules library in a high throughput screening experiment for inhibitors of the phosphodiesterase PDE4. It displays a significant preference for PDE4Bover PDE4A.

N, N – Dimethylarginine, more known as asymmetric dimethylarginine (ADMA), a naturally occurring chemical found in blood plasma. It is formed by methylation of arginine residues in proteins and released after proteolysis. ADMA is an endogenous inhibitor of all isoforms of nitric oxide synthase, the enzyme that synthesizes nitric oxide from arginine. Elevated plasma concentrations of ADMA are associated with hypertension and other risk factors for cardiovascular disease. It is known, that chronic kidney disease (CDK) is associated with increased risk of renal and cardiovascular events and it has been claimed that asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), are contributing factors. Nevertheless, the recent comprehensive analysis of methylarginines in a cohort of patients with non-dialysis CKD have revealed, the potential pathophysiological role of SDMA in CKD progression and atherosclerotic cardiovascular disease among non-dialysis CKD patients. Thus SDMA predicts CKD progression and future atherosclerotic cardiovascular events more consistently than other methylarginines. In addition, was also shown, that the maternal plasma ADMA concentration is an important indicator of fetal growth restriction in women with impaired placental perfusion independent of NO.

Isopimpinellin is a natural product synthesized by Umbelliferae (or Apiaceae), also known as the carrot or parsley family. It can be found in celery, garden angelica, parsnip, fruits and in the rind and pulp of limes. There have been several studies looking into the effects of Isopimpinellin and other so-called naturally occurring coumarins (such as bergamottin and Imperatorin) as anticarcinogens.

Carbon C-14 is an unstable, radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Radiocarbon dating is a radiometric dating method that uses (14C) to determine the age of carbonaceous materials up to about 60,000 years old. One of the frequent uses of the technique is to date organic remains from archaeological sites. Carbon-14 can be used as a radioactive tracer in medicine. In the initial variant of the urea breath test, a diagnostic test for Helicobacter pylori, urea labeled with approximately 37 kBq (1.0 μCi) carbon-14 is fed to a patient (i.e., 37,000 decays per second). In the event of a H. pylori infection, the bacterial urease enzyme breaks down the urea into ammonia and radioactively-labeled carbon dioxide, which can be detected by low-level counting of the patient's breath. The 14C urea breath test has been largely replaced by the 13C urea breath test, which has no radiation issues.