Brain-derived neurotrophic factor (BDNF), or abrineurin, is a protein that, in humans, is encoded by the BDNF gene. BDNF is a member of the neurotrophin family of growth factors, which are related to the canonical nerve growth factor (NGF), a family which also includes NT-3 and NT-4/NT-5. Neurotrophic factors are found in the brain and the periphery. BDNF was first isolated from a pig brain in 1982 by Yves-Alain Barde and Hans Thoenen.
Nerve growth factor (NGF) is a neurotrophic factor and neuropeptide primarily involved in the regulation of growth, maintenance, proliferation, and survival of certain target neurons. It is perhaps the prototypical growth factor, in that it was one of the first to be described. Since it was first isolated by Nobel Laureates Rita Levi-Montalcini and Stanley Cohen in 1956, numerous biological processes involving NGF have been identified, two of them being the survival of pancreatic beta cells and the regulation of the immune system.
Tropomyosin receptor kinase A (TrkA), also known as high affinity nerve growth factor receptor, neurotrophic tyrosine kinase receptor type 1, or TRK1-transforming tyrosine kinase protein is a protein that in humans is encoded by the NTRK1 gene.
Tropomyosin receptor kinase B (TrkB), also known as tyrosine receptor kinase B, or BDNF/NT-3 growth factors receptor or neurotrophic tyrosine kinase, receptor, type 2 is a protein that in humans is encoded by the NTRK2 gene. TrkB is a receptor for brain-derived neurotrophic factor (BDNF). Standard pronunciation is "track bee".
Tropomyosin receptor kinase C (TrkC), also known as NT-3 growth factor receptor, neurotrophic tyrosine kinase receptor type 3, or TrkC tyrosine kinase is a protein that in humans is encoded by the NTRK3 gene.
Neurotrophin-3 is a protein that in humans is encoded by the NTF3 gene.
N-Acetylserotonin (NAS), also known as normelatonin, is a naturally occurring chemical intermediate in the endogenous production of melatonin from serotonin. It also has biological activity in its own right, including acting as a melatonin receptor agonist, an agonist of the TrkB, and having antioxidant effects.
Discoidin domain receptor family, member 1, also known as DDR1 or CD167a, is a human gene.
SHC-transforming protein 3 is a protein that in humans is encoded by the SHC3 gene.
Gossypetin, also known as 3,5,7,8,3',4'-hexahydroxyflavone, is a flavonol, a type of flavonoid. It has been isolated from the flowers and the calyx of Hibiscus sabdariffa (roselle) and exhibits a strong antibacterial activity. The compound has also been found to act as an antagonist of TrkB. Recently it was shown that gossypetin has radioprotective activity.
Diosmetin, also known as 5,7,3′-trihydroxy-4′-methoxyflavone, is an O-methylated flavone, a chemical compound that can be found in the Caucasian vetch.
Tropoflavin, also known as 7,8-dihydroxyflavone, is a naturally occurring flavone found in Godmania aesculifolia, Tridax procumbens, and primula tree leaves. It has been found to act as a potent and selective small-molecule agonist of the tropomyosin receptor kinase B (TrkB), the main signaling receptor of the neurotrophin brain-derived neurotrophic factor (BDNF). Tropoflavin is both orally bioavailable and able to penetrate the blood–brain barrier. A prodrug of tropoflavin with greatly improved potency and pharmacokinetics, R13, is under development for the treatment of Alzheimer's disease.
Deoxygedunin, or 14,15-deoxygedunin, is a tetranortriterpenoid isolated from the Indian neem tree a plant that has been in traditional Indian medicine since ancient times as a remedy for various ailments.
ANA-12 is a selective, small-molecule non-competitive antagonist of TrkB, the main receptor of brain-derived neurotrophic factor (BDNF). The compound crosses the blood-brain-barrier and exerts central TrkB blockade, producing effects as early as 30 minutes and as long as 6 hours following intraperitoneal injection in mice. It blocks the neurotrophic actions of BDNF without compromising neuron survival.
LM22A-4 is a synthetic, selective small-molecule partial agonist of TrkB (EC50 for TrkB activation = 200–500 pM; IC50 for inhibition of BDNF binding to TrkB = 47 nM; IA = ~85%), the main receptor of brain-derived neurotrophic factor. It has been found to possess poor blood-brain-barrier penetration when administered systemically, so LM22A-4 has been given to animals instead via intranasal administration, with central nervous system TrkB activation observed. The compound produces neurogenic and neuroprotective effects in animals, and shows beneficial effects on respiration in animal models of Rett syndrome.
R7 is a small-molecule flavonoid and orally active, potent, and selective agonist of the tropomyosin receptor kinase B (TrkB) – the main signaling receptor for the neurotrophin brain-derived neurotrophic factor (BDNF) – which is under development for the treatment of Alzheimer's disease. It is a structural modification and prodrug of tropoflavin (7,8-DHF) with improved potency and pharmacokinetics, namely oral bioavailability and duration. R7 was synthesized by the same researchers who were involved in the discovery of tropoflavin. A patent was filed for R7 in 2013 and was published in 2015. In 2016, it was reported to be in the preclinical stage of development. R7 was superseded by R13 because while R7 had a good drug profile in animals, it showed almost no conversion into tropoflavin in human liver microsomes.
7,8,3′-Trihydroxyflavone (7,8,3'-THF) is a flavone and small-molecule agonist of TrkB, the main receptor of brain-derived neurotrophic factor (BDNF), that was derived from tropoflavin (7,8-DHF). Relative to tropoflavin, 7,8,3'-THF is 2–3-fold more potent in vitro as a TrkB agonist. 7,3’-Dihydroxyflavone (7,3'-DHF) is also more potent than tropoflavin in vitro, indicating that a 3'-hydroxy group on the B-ring enhances TrkB agonistic activity. 7,8,3'-THF has been tested in vivo and was found to produce TrkB-dependent neuroprotective effects in mice similarly to tropoflavin.
Eutropoflavin (4'-Dimethylamino-7,8-dihydroxyflavone) is a synthetic flavone and selective small-molecule agonist of TrkB, the main receptor of brain-derived neurotrophic factor (BDNF), which was derived from structural modification of tropoflavin (7,8-DHF). Relative to tropoflavin, eutropoflavin possesses higher agonistic activity at TrkB, is significantly more potent than tropoflavin both in vitro and in vivo, and has a longer duration of action. The compound has been found to produce neuroprotective and neurogenic effects in the brain and spinal cord as well as antidepressant-like effects in animals.
R13 is a small-molecule flavonoid and orally active, potent, and selective agonist of the tropomyosin receptor kinase B (TrkB) – the main signaling receptor for the neurotrophin brain-derived neurotrophic factor (BDNF) – which is under development for the potential treatment of Alzheimer's disease. It is a structural modification and prodrug of tropoflavin (7,8-DHF) with improved potency and pharmacokinetics, namely oral bioavailability and duration. The compound is a replacement for the earlier tropoflavin prodrug R7 and has similar properties to it. It was developed because while R7 displayed a good drug profile in animal studies, it showed almost no conversion into tropoflavin in human liver microsomes. In contrast to R7, R13 is readily hydrolyzed into tropoflavin in human liver microsomes.
Neurotrophin mimetics are small molecules or peptide like molecules that can modulate the action of the neurotrophin receptor. One of the main causes of neurodegeneration involves changes in the expression of neurotrophins (NTs) and/or their receptors. Indeed, these imbalances or changes in their activity, lead to neuronal damage resulting in neurological and neurodegenerative conditions. The therapeutic properties of neurotrophins attracted the focus of many researchers during the years, but the poor pharmacokinetic properties, such as reduced bioavailability and low metabolic stability, the hyperalgesia, the inability to penetrate the blood–brain barrier and the short half-lives render the large neurotrophin proteins not suitable to be implemented as drugs.
