PF-04447943 is a potent, selective brain penetrant PDE9 inhibitor (Ki of 2.8, 4.5 and 18 nM) for human, rhesus and rat recombinant PDE9 respectively and high selectivity for PDE9 versus PDEs1-8 and 10-11. PF-04447943 was being developed by Pfizer for the treatment of cognitive disorders. PF-04447943 attenuates a scopolamine-induced deficit in a novel rodent attention task. PF-04447943 enhances synaptic plasticity and cognitive function in rodents. PF-04447943 has completed Phase II clinical trials in subjects with mild to moderate AD in 2013 but this research was discontinued. Pfizer completes a phase I trial in Sickle cell anaemia.

3-Indolepropionic acid (IN-OX1; Indole-3-propionic acid; OX-1; Oxigon; SHP 22; SHP-622; VP-20629), an endogenous substance produced by bacteria in the intestine, is a deamination product of Tryptophan (T947200) that protects the hippocampus (studied in gerbils) from ischemic damage and oxidative stress. It’s ability to protect the neurons in this way is attributed to its potent antioxidative effects. 3-Indolepropionic acid is also hypothesized to have protective effects on the thyroid gland. 3-Indolepropionic acid is being studied for therapeutic use in Alzheimer's disease. 3-Indolepropionic acid (IPA) completely protected primary neurons and neuroblastoma cells against oxidative damage and death caused by exposure to Abeta, by inhibition of superoxide dismutase, or by treatment with hydrogen peroxide. In kinetic competition experiments using free radical-trapping agents, the capacity of IPA to scavenge hydroxyl radicals exceeded that of melatonin, an indoleamine considered to be the most potent naturally occurring scavenger of free radicals. In contrast with other antioxidants, IPA was not converted to reactive intermediates with pro-oxidant activity. In 2011, Intellect redirected the focus of the OX1 program from Alzheimer's disease to FA (Friedreich's Ataxia). Research suggests that the symptoms associated with FA are the result of oxidative stress caused by the abnormal accumulation of iron. OX1's ability to neutralize ROS could be an effective agent to reduce oxidative stress in FA, thereby eliminating the symptoms of FA and increasing both quality of life and longevity in affected individuals.

Xanthohumol is a prenylated flavonoid most abundant in hops. It is found in beers and refreshment drinks. It can attenuate several factors of the metabolic syndrome. It has been reported to inhibit adipogenesis or increase cell apoptosis and therefore can be used in preventing obesity. Xanthohumol inhibited angiogenesis by suppressing NF-κB activity in pancreatic cancer. Xanthohumol may represent a novel therapeutic agent for the management of pancreatic cancer. Moreover, it is in phase I clinical trials for preventing many types of cancer. It has a range of other biological properties: antiviral, antimalarial, antibacterial and as an osteoporosis preventing agent.

Pepstatin is a pentapeptide of microbial origin. The peptide inhibits the acid proteases pepsin and cathepsin D and the pressor enzyme renin. Pepstatin was shown to provide long-lasting inhibition (3 to 6 days) of cathepsin D in vivo in non-tumor bearers particularly in spleen, liver, kidney, lung, and heart. Pepstatin may prove useful as "anticachexia" agent by decreasing proteolysis in muscle and other tissues. The in vivo pepstatin and IL-2 treatment decreased the T-cells and increased the natural killer-like LAK precursor cells, possibly also with an increase in its activity, which were further induced by in vitro IL-2 culture to generate an augmented LAK cell activity. This suggests the clinical potential of pepstatin in IL-2-related immunotherapy. In rats injected centrally with the specific cathepsin D inhibitor, pepstatin, the protease activity was inhibited up to 90% in most brain regions.

Talsaclidine (WAL-2014) is a selective full agonist of M1 muscarinic receptor, having partial agonist activity on the M2 and M3 subtypes (with no in vivo consequences). The general receptor profile of talsaclidine demonstrates a nearly specific interaction with muscarinic receptors, having only weak binding affinity for alpha1- and nicotinic receptors. The drug is being tested in phase III of clinical trials for the treatment of Alzheimer's disease.

Avagacestat (BMS-708163) is an oral gamma secretase inhibitor designed for selective inhibition of amyloid beta (Aβ) synthesis. Avagacestat was in development by Bristol-Myers Squibb for the treatment of Alzheimer's disease (AD). Avagacestat is a potent, selective, orally bioavailable γ-secretase inhibitor of Aβ40 and Aβ42 with IC50 of 0.3 nM and 0.27 nM, demonstrating a 193-fold selectivity against Notch. In November 2012, Bristol-Myers Squibb terminated clinical trials of the drug and announced its decision to end further development of avagacestat

Mibampator, also known as LY451395, is a potent and highly selective an AMPA receptor potentiator, which plays a role in the regulation of the glutamatergic system. The AMPA system also has important functions in the regulation of synapses, synaptic regeneration, and neuroprotection and is therefore a good therapeutic target for treatments aiming to improve cognition and function or alter disease progression. Mibampator was in the phase II clinical trial for the treatment of agitation and aggression in Alzheimer's disease (AD).

Baicalein is a flavonoid is a component of the traditional herbal remedy known as Chinese skullcap (or Huang Qin), possesses various biological activities. Baicalein is a neuroprotective agent, which is studied in phase I for the treatment of Parkinson’s disease. By modulating of γ-aminobutyric acid (GABA) type A receptors, baicalein promotes nonamyloidogenic processing of amyloid precursor protein (APP), thereby reducing β-amyloid (Aβ) production and improving cognitive performance in models of Alzheimer's disease. By inhibiting the NF-κB signaling pathway, baicalein suppressed cancer cells proliferation and suppressed the viability of human endometrial stromal cells, thus it may provide a novel treatment option for endometriosis. Besides, this compound was evaluated for its ability to inhibit the influenza virus. Experiments on mice have shown that baicalein showed significant effects in preventing death, increasing the mean time to death and reducing the lung virus titer in a dose-dependent manner.

Intepirdine, also known as SB-742457, RVT-101, was originally developed by GlaxoSmithKline (GSK) as an antagonist of the serotonin receptor 6 (5-HT6). GSK sold the rights for further study of this drug to Axovant Sciences in 2014. Intepirdine is in phase 3 clinical trial for Alzheimer's and in a phase 2 trial for dementia with Lewy bodies.

Igmesine is a sigma-1 receptor agonist. It was assayed in clinical trials targeting major depressive disorder. Igmesine is the only antisecretory agent that we have tested to date that inhibits both cholera toxin and the E. coli enterotoxins. Sigma receptors are known to be present on nerves in the enteric nervous system and this would seem to be a potentially useful class of drugs to pursue for the treatment of secretory diarrhoea in humans. It was shown that when Alzheimer's disease rats were submitted to the conditioned fear stress test, igmesine can significantly reduce the stress-induced motor suppression, indicating exogenous σ-1 receptor agonists may alleviate Alzheimer's disease-associated depressive symptoms.