3-Methylpyrazole

2-Aminomethylthieno[3,2-d]pyrimidin-4(3H)-ones bearing 3-methylpyrazole hinge binding moiety: Highly potent, selective, and time-dependent inhibitors of Cdc7 kinase

In order to increase the success rate for developing new Cdc7 inhibitors for cancer therapy, we explored a new chemotype which can comply with the previously-constructed pharmacophore model. Substitution of a pyridine ring of a serendipitously-identified Cdc7 inhibitor 2b with a 3-methylpyrazole resulted in a 4-fold increase in potency and acceptable kinase selectivity, leading to the identification of thieno[3,2-d]pyrimidin-4(3H)-one as an alternative scaffold. Structure-activity relationship (SAR) study revealed that incorporation of a substituted aminomethyl group into the 2-position improved kinase selectivity. Indeed, a pyrrolidinylmethyl derivative 10c was a potent Cdc7 inhibitor (IC50=0.70nM) with high selectivity (Cdk2/Cdc7≥14,000, ROCK1/Cdc7=200). It should be noted that 10c exhibited significant time-dependent Cdc7 inhibition with slow dissociation kinetics, cellular pharmacodynamic (PD) effects, and COLO205 growth inhibition. Additionally, molecular basis of high kinase selectivity of 10c is discussed by using the protein structures of Cdc7 and Cdk2.

Alteration in the plasma concentration of a DAAO inhibitor, 3-methylpyrazole-5-carboxylic acid, in the ketamine-treated rats and the influence on the pharmacokinetics of plasma D-tryptophan

A determination method for 3-methylpyrazole-5-carboxylic acid (MPC), an inhibitor of D-amino acid oxidase (DAAO), in rat plasma was developed by using high-performance liquid chromatography-mass spectrometry (LC-MS). The structural isomer of MPC, 3-methylpyrazole-4-carboxylic acid, was used as an internal standard, and the intra- and inter-day accuracies and precisions were satisfactory for the determination of plasma MPC.Next, the LC-MS method was applied to determine the plasma MPC concentration in ketamine (Ket)-treated rats after intraperitoneal administration of MPC (5.0 or 50 mg·kg(-1)). The C(max) value of plasma MPC concentration in the Ket-treated rats was significantly higher than that in the control group when a high dose of MPC (50 mg·kg(-1)) was administered. In addition, it was found that plasma D-tryptophan (D-Trp) concentration in Ket-treated rats administered D-Trp was not significantly increased by MPC, suggesting that the DAAO-inhibitory effect of MPC is attenuated in Ket-treated rats.

A hydrogen-bonded chain of rings in 5-amino-1-(4-methoxybenzoyl)-3-methylpyrazole and a three-dimensional hydrogen-bonded framework in 5-amino-3-methyl-1-(2-nitrobenzoyl)pyrazole

The molecules of 5-amino-1-(4-methoxybenzoyl)-3-methylpyrazole, C(12)H(13)N(3)O(2), (I), and 5-amino-3-methyl-1-(2-nitrobenzoyl)pyrazole, C(11)H(10)N(4)O(3), (II), both contain intramolecular N-H...O hydrogen bonds. The molecules of (I) are linked into a chain of rings by a combination of N-H...N and N-H...pi(arene) hydrogen bonds, while those of (II) are linked into a three-dimensional framework structure by N-H...N and C-H...O hydrogen bonds.

Coumarin derivatives as inhibitors of d-amino acid oxidase and monoamine oxidase

d-Amino acid oxidase (DAAO) oxidises d-amino acids to ultimately produce the corresponding α-keto acids. The DAAO substrate, d-serine, is a co-agonist at NMDA receptors, while NMDA receptor hypo-function has been implicated in the pathophysiology of schizophrenia. Through the modulation of d-serine levels, the inhibition of DAAO represents a strategy to increase NMDA receptor function, and thus a potential treatment for schizophrenia. Literature reports that 3-hydroxycoumarin is a potent inhibitor of DAAO and represents an ideal lead for the development of novel DAAO inhibitors. Based on this, the present study investigated DAAO inhibition by a series of synthetic and commercially available coumarin derivatives. Due to structural similarity to coumarin, a synthetic series of 3,4-dihydroisoquinolin-1(2H)-one derivatives has also been included in this study. The results show that among 37 compound evaluated, four inhibit porcine kidney DAAO with IC₅₀ < 10 ?M. The most potent inhibitors are 3,7-dihydroxycoumarin and 6,7-dihydroxycoumarin with an IC₅₀ values of 0.167 and 0.224 ?M, respectively. These values are an improvement on that of the reference DAAO inhibitor, 3-methylpyrazole-5-carboxylic acid (IC₅₀ = 1.88 ?M). Coumarin compounds are also known to inhibit the monoamine oxidase (MAO) enzymes, which are well established targets for the treatment of depression and Parkinson's disease. As DAAO and MAO are flavoenzymes, off-target inhibition may occur. The series were thus evaluated as potential MAO inhibitors, and a number of high potency inhibitors were identified. Seven compounds inhibit the recombinant human MAOs with IC₅₀ < 0.1 ?M, with the most potent MAO-A and MAO-B inhibitors exhibiting IC₅₀ values of 0.033 and 0.012 ?M, respectively. This is significantly more potent than the reference inhibitors, curcumin, isatin and toloxatone. This study concludes that active DAAO and MAO inhibitors may serve as novel leads for the design of compounds that may find future application in the treatment of neuropsychiatric (e.g. schizophrenia, depression) and neurodegenerative disorders (e.g. Parkinson's disease).

Determination of 4-methylpyrazole in plasma using solid phase extraction and HPLC

A rapid method for the determination of 4-methylpyrazole in plasma is described. Internal standard (3-methylpyrazole) is added to the plasma which is subsequently applied to a BondElut SCX column. After washing the column the 3- and 4-methylpyrazoles are eluted with a phosphate buffer and analyzed by isocratic reversed-phase high performance liquid chromatography with UV detection. The concentration of 4-methylpyrazole is calculated from the 4-methylpyrazole/3-methylpyrazole peak height ratio. The method is linear between 2.5 and 100 mumol/L with a within-day precision (CV) of 2.2% (n = 10) and a day-to-day precision of 2.8% (n = 30). The sensitivity is sufficient for analysis of plasma levels in the low micromolar range.