Bitopertin is a Glycine transporter type 1 inhibitor which was developed by Hoffmann-La Roche for the treatment of patients with schizophrenia. The drug was shown to be potent in vitro, however it failed to meet primary endpoints in phase III. Bitopertin was also tested for the treatment of obsessive-compulsive disorder, but the development stopped in phase II.

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

Quinelorane is an octahydropyrimido[4,5-g]quinolone derivative patented by American pharmaceutical company Eli Lilly and Co. as for the treatment anxiety, Parkinson's syndrome, depression, and hypertension. Quinelorane acts as an agonist of dopamine agonist for the D2 and D3 receptors. In preclinical studies Quinelorane (IM) treatment produced dose-dependent effects on male sexual responding. Penile erections and masturbation were markedly facilitated following treatment with either 2.5 or 5 micrograms/kg quinelorane. Higher doses of quinelorane (10 and 25 micrograms/kg) generally did not further augment sexual responding but rather resulted in a return in sexual responding to control vehicle levels. Quinelorane had a biphasic effect on yawning behavior of the monkeys with low doses (2.5 and 5 micrograms/kg) facilitating yawning and high doses (25 micrograms/kg) inhibiting yawning.

DDP-225 (also known as MCI-225), a thienopyrimidine analog, is a selective noradrenaline reuptake inhibitor with serotonin receptor antagonism. It shows antidepressant-like properties in animal models. MCI-225 could be useful in the treatment of attentional deficits and related cognitive dysfunctions in psychiatric disorders.

Nebracetam (WEB1881FU) is a pyrrolidinone nootropic. Like other racetams, it is an aminomethyl pyrrolidinone derivative of piracetam. It was first synthesized in Germany in the late 1980s, where it was manufactured by Boehringer Ingelheim. Nebracetam is a M1-muscarinic agonist. In Jurkat cells Nebracetam induced a rise of [Ca2+]i in the medium with 1 mM Ca2+ and without Ca2+ (plus 1 mM EGTA). The nebracetam-induced [Ca2+]i rise was blocked by atropine greater than pirenzepine greater than AF-DX 116. Nebracetam facilitates the ganglionic muscarinic transmission through acting on presynaptic sites. Nebracetam has been investigated as a cognition-enhancing drug, but most of the studies have taken place in animal models. It has been shown to protect neurons in animals exposed to low levels of oxygen and low blood sugar. Nebracetam is also protective against glutamate toxicity, presumably via its modulation of calcium entry. In animal models of Alzheimer’s disease, nebracetam improved memory in a dose-dependent manner. It also protected against ischemia- (lack of oxygen) induced neuronal death in a rat model of stroke. The compound has also been tested as a possible antidepressant, presumably because its mechanism of action (reducing dopaminergic and serotonergic uptake) is similar to other commonly used antidepressants. Some studies have taken place in humans. A single dose was shown to alter brain waves in healthy volunteers, who showed increased alpha activity and an associated decrease of slow activity and of fast activity in the frontal cortex. These results imply that nebracetam might improve linguistic learning and memory processing. A trial in dementia patients reported that significant clinical improvement occurred after 8 weeks. However, other studies did not replicate this finding.

Oxaprotiline (also known as hydroxymaprotiline) is a norepinephrine reuptake inhibitor and blocked the histamine H1 receptor. Oxaprotiline was studied in the treatment of hospitalized depressive patients. However, this drug has never been marketed.

Arctigenin is a plant lignan extracted from Arctium lappa that has been shown to have estrogenic properties. In ER-positive MCF-7 cells, arctigenin efficiently inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell migration and invasion. Arctigenin confers anti-metastatic effects by inhibiting MMP-9 and uPA via the Akt, NF-κB and MAPK signaling pathways on breast cancer, regardless of ER expression. Intake of arctigenin could be an effective supplement for breast cancer patients. Arctigenin is a phenylpropanoid dibenzylbutyrolactone lignan compound possessing antitumor, anti-inflammatory, anti-influenza, antioxidant, antibacterial, and hypoglycaemic activities. Arctigenin exhibited significant antiproliferative activity against CCRF-CEM cells after 72 h treatment with IC50 values of 1.21 ± 0.15 um. It arrested CCRF-CEM cells in the S phase. It induced apoptosis in CCRF-CEM cells in a concentration- and time-dependent manner. Arctigenin is a good candidate for the development of novel agents against T-cell lymphoma. Arctigenin has been found to act as an agonist of adiponectin receptor 1 (AdipoR1). Arctigenin is an antagonist of MR and effectively decreases the Na/K-ATPase 1 gene expression, thus highlighting its potential as an anti-hypertensive drug lead compound.

Tropanserin (MDL 72422) is a potent and selective 5-HT3 receptor antagonist. It was investigated as a drug for the treatment of migraine. MDL 72222 was shown to be an effective antimigraine agent in a double-blind placebo-controlled study.

Semapimod (CNI-1493) is a cytokine inhibitor and synthetic guanylhydrazone mitogen-activated protein kinase blocker, is being developed by Cytokine PharmaSciences as a potential treatment for Crohn's disease and other inflammatory conditions. As of December 2001, a phase I study demonstrating the safety of the compound had been completed and phase II trials for psoriasis and Crohn's disease were ongoing. In April 2003, preclinical and early clinical studies were underway for a variety of indications, including congestive heart failure and pancreatitis. Semapimod inhibits activation of p38 MAPK and NF-κB and induction of cyclooxygenase-2 by TLR ligands, but not by IL-1β or stresses. Semapimod inhibits TLR4 signaling (IC50 ≈0.3 umol) and acts by desensitizing cells to LPS; it fails to block responses to LPS concentrations of ≥5 ug/ml. Semapimod had been in phase II clinical trials by Ferring Pharmaceuticals for the treatment of Crohn's disease. However, this research has been discontinued. Semapimod is in phase I clinical trials for the treatment of autoimmune disorders and inflammation.

β-N-Acetyl-D-galactosamine (GalNAc) is an amino sugar derived from galactose found in O-linked and N-linked glycans. As an essential sugar, the role is basically the same for N-acetylgalactosamine as it is for the others, which is to enhance cellular communication. Although there has not been much research to date, what has been done reveals that this saccharide may inhibit the growth of some tumors. For example, colon cancer patients have only half the normal amounts of N-acetylgalactosamine. Studies have shown that colon cancer cells that metastasize make more mucin, making them more likely to form metastases. Therefore, it appears that N-acetylgalactosamine plays an important role in preventing this formation from occurring. N-acetylgalactosamine and N-acetylglucosamine glycans is a predictor of metastasis and poor prognosis in a number of human adenocarcinomas, including breast cancer. Lower than normal levels of this sugar has been found in patients with heart disease implying that these conditions may be reversed if a supplementation of N-acetylgalactosamine were to be added to the diet. It appears that β-N-Acetyl-D-galactosamine plays a role in joint function, sweeping away destructive free radicals that can cause inflammation. N-acetylgalactosamine also seems to play an important role in the immune system. Contained in macrophages and neutrophils, it may play a significant role in the etiology of joint inflammation and could be important in such conditions as rheumatoid arthritis. In humans, it is the terminal carbohydrate forming the antigen of blood group A. N-acetylgalactosamine (GalNAc) is a well-defined liver-targeted moiety benefiting from its high affinity with asialoglycoprotein receptor (ASGPR). By conjugating it directly to the oligonucleotides or decorating it to a certain delivery system as a targeting moiety, GalNAc has achieved compelling successes in the development of nucleic acid therapeutics in recent years. Several oligonucleotide modalities are undergoing pivotal clinical studies, followed by a blooming pipeline in the preclinical stage. N-Acetyl-D-galactosamine is used in affinity chromatography, protein chromatography and in carbohydrate matrices. N-Acetyl-D-galactosamine has been used to study periodontal disease and to facilitate the design of potent small-molecule ice recrystallization inhibitors. N-Acetyl-D-galactosamine has also been used to demonstrate a molecular shuttle between extracellular and cytoplasmic space allows for monitoring of GAG biosynthesis.