Homocysteine, an amino acid synthesized intracellularly by removal of the N-methyl group from the essential amino acid methionine. High plasma level of homocysteine is called hyperhomocysteinemia is a clinical biomarker for increased risk of cardiovascular disease, thromboembolic diseases, and myocardial infarction. It was shown, that hyperhomocysteinemia could be an independent risk factor for dementia and Alzheimer's disease. The falling of homocysteine concentrations in response to increasing B-group-vitamin status, have the hope that mental decline, or Alzheimer's disease, could be prevented by dietary modification or food fortification. Besides, homocysteine can behave as an anti-oxidant agent by increasing the antioxidant capacity of the tumor and endothelial cells.

Norleucine (L-norleucine) is a 2-aminohexanoic acid is an alpha-amino acid that is caproic acid substituted by an amino group at position 2. It derives from a hexanoic acid. It is used experimentally to study protein structure and function. Norleucine appears to inhibit bacterial growth due to incorporation into proteins in place of methionine, as the analogue inhibits methionine incorporation but does not significantly reduce its synthesis. L-norleucine had antiviral activity in thermophile. In vitro and in vivo assays revealed that L-norleucine significantly suppressed metastasis of gastric and breast cancer cells. L-norleucine interacted with hnRNPA2/B1 protein to inhibit the expressions of Twist1 and Snail, two inhibitors of E-cadherin, and promote the E-cadherin expression, leading to the inhibition of tumor metastasis.

Folitixorin, a thymidylate synthase inhibitor is a substrate used by the enzyme methylenetetrahydrofolate reductase (MTHFR) to generate 5-methyltetrahydrofolate. Folitixorin was studied in clinical trials for the treatment of breast cancer, metastatic colorectal cancer and for the treatment of advanced pancreatic cancer. Folitixorin had been granted orphan drug status for the treatment of pancreatic cancer in both the U.S. and EU. However, further development of this drug was discontinued.

Methylselenocysteine is a part of the mammalian physiology and is a well-tolerated, versatile and economical antiangiogenic agent. This compound participated in clinical trial to determine if vitamin supplementation with this compound could restore disruption of circadian rhythm in shift workers. The preclinical efficacy of methylselenocysteine has shown the combination of methylselenocysteine with androgen deprivation therapy can be useful for the treatment of advanced prostate cancer.

Namirotene [CBS-211A] is a retinoic acid analogue which was undergoing phase II trials with Chauvin in France as 0.02% eye drops for corneal ulcer. It was discontinued later. Namirotene is a synthetic analogue of retinoic acid with differentiation inducing and potential antineoplastic activities. Like other retinoic acid agents, namirotene binds to and activates retinoic acid receptors (RARs), thereby altering the expression of certain genes leading to cell differentiation and decreased cell proliferation in susceptible cells. When it was associated with 1 alpha,25(OH)2D3, CBS-211A strongly potentiated the 1 alpha,25(OH)2D3-induced inhibition of U937 cell proliferation and caused a dramatic increase in their differentiation toward monocytes/macrophages. The co-inducing effect of CBS-211A was restricted to U937 cells. Our data suggest that CBS-211A may have therapeutic implications in the treatment of certain kinds of myelomonocytic leukemia. CBS-211A also provides an interesting tool to understand the mechanisms involved in the differentiation of myelomonocytic cells.

Bensuldazic acid was used in veterinary as an antifungal agent.

Mofarotene is an analog of retinoic acid patented by a Swiss multinational healthcare company Hoffmann-La Roche as neoplasm inhibitors and agent for treating dermatoses. Like other retinoic acid agents, mofarotene binds to and activates retinoic acid receptors (RARs), thereby altering the expression of certain genes leading to cell differentiation and decreased cell proliferation in susceptible cells. Mofarotene has demonstrated considerable antitumor activity in a number of cancer cell lines. Mofarotene in combination with cisplatin and etoposide was studied in phase I clinical trials but further development was discontinued.

Fenretinide (4-HPR) is an orally-active synthetic phenylretinamide analogue of retinol (vitamin A) with potential antineoplastic and chemopreventive activities. Fenretinide binds to and activates retinoic acid receptors (RARs), thereby inducing cell differentiation and apoptosis in some tumor cell types. This agent also inhibits tumor growth by modulating angiogenesis-associated growth factors and their receptors and exhibits retinoid receptor-independent apoptotic properties. Phase III clinical trial data has suggested that fenretinide reduces breast cancer relapse in pre-menopausal women. Fenretinide is the most studied retinoid in breast cancer chemoprevention clinical trials due to its selective accumulation in breast tissue and its favorable toxicological profile. This agent showed a significative reduction of the incidence of second breast tumors in premenopausal women confirmed after 15-year followups. Fenretinide, a drug being developed by Sirion Therapeutics, slowed the progression of advanced dry age-related macular degeneration (AMD) by 45 percent for people receiving a higher dose of the treatment in a Phase II clinical trial. Sirion has been granted a Fast Track designation for the treatment by the FDA. Fenretinide is in phase II clinical trials for the treatment of B-cell lymphoma, chronic lymphocytic leukemia. It is also in phase I clinical trials for the treatment of cystic fibrosis.