Tumor hypoxia remains one of the greatest challenges in the treatment of solid tumors, as cancer cells in these regions are resistant to killing by radiation therapy and most anticancer drugs. Tirapazamine (3-Amino-1,2,4-benzotriazine-1,4-dioxide or SR 4233) is a cytotoxic drug with selective toxicity towards hypoxic mammalian cells. Under both aerobic and hypoxic conditions, tirapazamine is reduced by an intracellular reductase to form a highly reactive radical, which can cause DNA single- and double-strand breaks. In addition, tirapazamine under hypoxic conditions reduces the activity of topoisomerase II and stabilizes DNA topoisomerase II cleavable complexes, and these complexes remain bound to DNA. Despite the very promising results obtained in various preclinical studies and early-Phase clinical trials, several Phase III trials have failed to demonstrate any survival benefit of adding tirapazamine to chemotherapy or radiation therapy of cancers.

Quinacrine was initially developed as an anti-malarial drug marketed under the name Atabrine. Also it was approved for the teratment of ascites, however it was wothdrawn for both indication in 1995 and 2003, respectively. The drug is also used for the treatment of giardiasis, lupus, rheumatoid arthritis, refractory pulmonary effusion and pneumothorax, induce female sterilization etc. Proposed mechanisms of action include DNA intercalation interference with RNA transcription and translation, inhibition of succinate oxidation interference with electron transport, inhibition of cholinesterase, and inhibitor of phospholipase.

Propionic acid (PA), also known as propanoic acid, with chemical formula C3H6O2, is an organic acid used as a food additive and found naturally on the skin and in the gastrointestinal tract. It is a byproduct of fermentation reactions and is also produced industrially from ethylene or ethanol and carbon monoxide. Propionic acid is a fungicide and bactericide, registered to controlfungi and bacteria in stored grains, hay, grain storage areas, poultry litter,and drinking water for livestock and poultry. As a food preservative, propionic acid prevents mold in bread and baked goods, and it is used as a flavoring agent in cheese and other packaged goods. The U.S. Environmental Protection Agency considers it safe and therefore, has no limitation on its use. It has been demonstrated that PA lowers fatty acids content in liver and plasma, reduces food intake, exerts immunosuppressive actions and probably improves tissue insulin sensitivity. Thus increased production of PA by the microbiota might be considered beneficial in the context of prevention of obesity and diabetes type 2. The molecular mechanisms by which PA may exert this plethora of physiological effects are slowly being elucidated and include intestinal cyclooxygenase enzyme, the G-protein coupled receptors 41 and 43 and activation of the peroxisome proliferator-activated receptor γ, in turn inhibiting the sentinel transcription factor NF-κB and thus increasing the threshold for inflammatory responses in general. Taken together, PA emerges as a major mediator in the link between nutrition, gut microbiota and physiology. The sodium salt of propionic acid was previously approved in Canada as an active ingredient in Amino-Cerv (used to treat inflammation or injury of the cervix).

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.

Menatetrenone (INN), also known as MK4, is a vitamin K compound used as a hemostatic agent, and also as adjunctive therapy for the pain of osteoporosis. MK4 is marketed for the osteoporosis indication in Japan by Eisai Co., under the trade name Glakay. Has several mechanism of actions: (1) Acceleration of osteogenesis. In human osteoblast cultures, calcification was accelerated by administration of menatetrenone at a concentration of 2.25 × 10-6 mol/L alone or when it was coadministered with 1,25(OH)2D3. The osteocalcin content in the cell layers was increased by coadministration with 1,25(OH)2D3. 2. Inhibition of bone resorption. In organ cultures of mouse calvaria, at concentrations of 3 × 10-6 to 3 × 10-5 mol/L, menatetrenone inhibited bone resorption induced by IL-1α, PGE2, PTH and 1,25(OH)2D3. In mouse bone marrow cell cultures, at concentrations of 3 × 10-6 to 1 × 10-5 mol/L, menatetrenone inhibited the induction of osteoclast release by 1,25(OH)2D3. 3. Effect on serum level of osteocalcin. Menatetrenone was administered to patients with osteoporosis at a dose of 45 mg/day for 2 years. Menatetrenone increased the serum level of osteocalcin and decreased the serum level of Glu-osteocalcin.

Butyric acid (butanoic acid) belongs to a group of short-chain fatty acids and is thought to play several beneficial roles in the gastrointestinal tract. The butyric anion is easily absorbed by enteric cells and used as a main source of energy. Moreover, butyric acid is an important regulator of colonocyte proliferation and apoptosis, gastrointestinal tract motility and bacterial microflora composition in addition to its involvement in many other processes including immunoregulation and anti-inflammatory activity. Butyric acid shows a protective effect in inflammatory response secondary to inflammatory bowel diseases. A beneficial effect of butyric acid as one constituent of a multifaceted mechanism modulating gastrointestinal function has also been stressed in patients with the stoma and coexisting constipation. Butyric acid supplementation combined with the use of probiotics should be adopted as one of the basic therapeutic strategies in this patient group, preceding treatment with laxatives. Sodium butyrate in the form of enemas (combined in a mixture with A-300 silicon dioxide) may be a successful method of therapeutic management in patients with radiation proctitis. Sodium butyrate may also prevent diarrhea through an increased passive absorption of water in the colon and its effects on the gut microflora.

Apatinib is an orally bioavailable, small molecule tyrosine kinase inhibitor that selectively inhibits the vascular endothelial growth factor receptor-2 and used for the treatment of metastatic gastric cancer or gastroesophageal junction cancer that has progressed or relapsed after chemotherapy. To date, second-line ramucirumab and third-line Apatinib are the only anti-angiogenic approaches that have significantly improved the survival of patients with metastatic gastric cancer. Apatinib exhibited potent, highly-selective inhibition of VEGFR-2, c-kit, c-src, and RET tyrosine kinases. The efficacy of Apatinib monotherapy in patients with metastatic gastric cancer or gastroesophageal junction cancer for whom at least two prior chemotherapy regimens had failed was demonstrated in randomized open-label or double-blind phase II trials and a pivotal placebo-controlled phase III trial, all of which were conducted in China. Further clinical experience and long-term pharmacovigilance are required to definitively establish the efficacy and safety profile of Apatinib, including its use in combination with other chemotherapeutic agents.

Ubenimex is a dipeptide, which specificallyinhibits the activity of leukotriene A4 hydrolase, aminopeptidase B and leucine aminopeptidase of the cell membrane. The drug was isolated from Streptomyces oliooreticuli in 1976 in Nippon Kayaku, Japan and approved for the treatment of acute non-lymphocytic leukemia under the name Bestatin. In the USA the drug is currentlu in Phase II for the treatment of pulmonary arterial hypertension and lymphedema.