MK-0657, (+)-, a MK 0657 - cis-(+)-isomer, relates to N-substituted nonarylheterocyclic compounds, N-methyl-D-aspartate subunit 2B (NMDA NR2B) antagonists which were developed by Merck as a candidate drugs for the treatment of Parkinson's disease and pain. There are no studies on MK 0657 - cis-(+)-isomer activity.

(2S)-1-((2S)-2-(((1R)-1-(Ethoxycarbonyl)-3-Phenylpropyl)Amino)Propanoyl)Pyrrolidine-2-Carboxylic Acid is an epimer and synthetic impurity of Enalpril which is an angiotensin-converting-enzyme (ACE) inhibitor used in the treatment of hypertension, diabetic nephropathy, and some types of chronic heart failure.

L-368,899 is a potent and selective oxytocin (OT) receptor antagonist, which was developed by Merc as a promising non peptide OT antagonist. However, this compound failed in clinical development; phase II, for the treatment of premature labour. Merck subsequently abandoned its non peptide OT antagonist program.

13-cis Retinol is one of the active metabolite of Vitamin A (all-trans Retinol). 13-cis Retinol is a retinoid inapplicable to the visual processes, and therefore it could be an important catabolic metabolite and its biosynthesis could be part of a process involved in regulating 11-cis-retinol concentrations within the retinal pigment epithelium of 11-cis-retinol dehydrogenase.

MK-5172 (Grazoprevir) intermediate. Grazoprevir is a second generation NS3/4A protease inhibitor approved in the EU and the USA for the treatment of hepatitis C virus (HCV) genotypes 1 and 4 infections in adult patients in combination with elbasvir (C virus (HCV) NS5A inhibitor) as the fixed-dose combination product Zepatier with or without ribavirin.

MK-6892 is niacin receptor 2 agonist, developed by Merkc. In preclinical experiments, it demonstrated reduction of free fatty acid levels by ~85%, with flushing side-effect evident only at the highest dose tested.

MK-8776 (SCH-900776) is a checkpoint kinase 1 inhibitor which was developed by Merck for the treatment of cancer. The drug was tested in phase II clinical trials on patients suffering from acute myeloid leukemia (in combination with cytarabine) and in phase I on patients suffering from solid tumors or lymphoma (as monotherapy and in combination with gemcitabine).

MK-912 is non-specific alpha-2 adrenergic receptor antagonist, with high affinity for the alpha-2-A, alpha-2B, and alpha-2C variants. Originally developed by Merk & Co, it has been investigated for potential therapeutic properties for the treatment of depression and diabetes. MK-912 is also regularly used as a molecular probe in biomedical studies seeking information about alpha-2 adrenergic receptors.

Ethylisopropylamiloride (5-(N-ethyl-N-isopropyl)-Amiloride, EIPA) is a potent inhibitor of several Sodium-hydrogen exchangers (NHE) isoforms, inhibiting NHE1, NHE2, NHE3, and NHE5, that potentially can be used in cancer treatment. Ethylisopropylamiloride was also demonstrated to inhibit a wide variety of cation channels such as KATP channels) peptide-gated Na+ channels and shrinkage-activated Na+ channels. EIPA is commonly used at a concentration of 5-10 μM to inhibit cellular HNE activity.

Biocytin is a biotin-lysine complex of low molecular weight containing about 65% biotin, which retains a high affinity for avidin. Biocytin is also used in scientific research as a histological stain for nerve cells. Biocytin is a versatile marker used in anterograde, retrograde and intracellular neuroanatomical investigations and in biotinidase assays. Biocytin displays high solubility in aqueous solutions and has a low molecular weight facilitating injection using micropipettes. Biocytin can be incorporated with a variety of avidin and streptavidin conjugates for detection by light, fluorescence or electron microscope. In vitro injection of biocytin into explanted brain hemispheres provides a quick and easy method for tract tracing in developing brains. Biocytin can be used to measure the biotinidase activity and therefore diagnose biotinidase deficiency.