Design and synthesis of 1-aryl-5-anilinoindazoles as c-Jun N-terminal kinase inhibitors.

Starting from pyrazole HTS hit (1), a series of 1-aryl-1H-indazoles have been synthesized as JNK3 inhibitors with moderate selectivity against JNK1. SAR studies led to the synthesis of 5r as double digital nanomolar JNK3 inhibitor with good in vivo exposure.

The development of benzimidazoles as selective rho kinase inhibitors.

Rho Kinase (ROCK) is a serine/threonine kinase whose inhibition could prove beneficial in numerous therapeutic areas. We have developed a promising class of ATP-competitive inhibitors based upon a benzimidazole scaffold, which show excellent potency toward ROCK (IC(50)<10nM). This report details the optimization of selectivity for ROCK over other related kinases such as Protein kinase A (PKA).

Indirect oxidation of amino acid phenylhydrazides by mushroom tyrosinase.

We have investigated oxidation of amino acid phenylhydrazides by mushroom tyrosinase in the presence of 4-tert-butylcatechol and N-acetyl-L-tyrosine. Spectrophotometric measurements showed gradual disappearance of 4-tert-butyl-o-benzoquinone, generated by oxidation of 4-tert-butylcatechol with sodium periodate, after addition of amino acid phenylhydrazides. However, the presence of the phenylhydrazides did not influence the concentration of 4-tert-butyl-o-benzoquinone formed during enzymatic oxidation. Oxygen consumption measurements demonstrated that in a mixture both compounds were oxidized but the reaction rate was proportional to the concentration of the catechol. In the oxidation of N-acetyl-L-tyrosine addition of phenylhydrazides shortened the lag period, indicating that they acted as reducing agents, converting N-acetyl-L-dopaquinone to N-acetyl-L-dopa. In HPLC analysis of the oxidation 4-tert-butylcatechol and the phenylhydrazide of Boc-tryptophan only the N-protected amino acid and 4-tert-butyl-o-benzoquinone were detected as final products. In the presence of the natural substrates the oxidation of amino acid phenylhydrazides required much smaller amounts of the enzyme and was up to 40 times faster than the reaction carried out without these compounds. These results demonstrate that tyrosinase can oxidize phenylhydrazides indirectly through o-quinones. This reaction explains the inhibitory effect of agaritine, a natural amino acid hydrazide, on melanin formation and the inhibitory effects of other hydrazine derivatives on tyrosinase described in the literature.

Anticonvulsant and antidepressant activity of the selected terpene GABA derivatives in experimental tests in mice.

The present study was designed to investigate the central nervous system activity of terpene GABA (and piracetam) derivatives designated as BF-1, BF-2, BF-3, BF-4, BF-5, BF-6. We assessed their anticonvulsant activity in the two main mouse models of seizures (MES-test, PTZ-test), an antidepressant-like effect in the forced swim test (FST), as well as an influence on spontaneous locomotor activity. Our study demonstrated the strong anticonvulsant activity of (1S,3R,7R)-(-)-3,8,8-trimethyl-4-aza-bicyclo[5.1.0]acetate-5-one hydrochloride (compound BF-2) in the PTZ-test. Activity of BF-2 was equipotent to ethosuximide (380 mg/kg, po) in the PTZ-test, when used at a dose of 100 mg/kg, po. No neurotoxic effects were demonstrated by administration of all tested compounds. Moreover, BF-2, BF-3, BF-6 compounds significantly reduced the immobility time in FST at both doses (by 21-50%), while BF-5 induced a significant anti-immobility effect only when used at a dose of 100 mg/kg (by 39%). The compound BF-6 used at the dose of 30 mg/kg was the most active (50% reduction), and the effect was similar to the result obtained with classical antidepressant--imipramine. The motor stimulatory activity was demonstrated by BF-1 compound at the dose of 100 mg/kg with no effect at a lower (30 mg/kg) dose. On the other hand, the BF-3 at 30 mg/kg significantly decreased spontaneous activity during 30 min observation period, while no alteration in this activity during 6-min observation was detected. At present, it is not possible to indicate which mechanisms of novel, active terpene GABA derivatives are involved in the demonstrated antidepressant-like activity. Although further studies are needed to solve this issue, these data suggest a potential value of the examined terpene GABA derivatives.

Structure-activity relationships and X-ray structures describing the selectivity of aminopyrazole inhibitors for c-Jun N-terminal kinase 3 (JNK3) over p38.

c-Jun N-terminal kinase 3alpha1 (JNK3alpha1) is a mitogen-activated protein kinase family member expressed primarily in the brain that phosphorylates protein transcription factors, including c-Jun and activating transcription factor-2 (ATF-2) upon activation by a variety of stress-based stimuli. In this study, we set out to design JNK3-selective inhibitors that had >1000-fold selectivity over p38, another closely related mitogen-activated protein kinase family member. To do this we employed traditional medicinal chemistry principles coupled with structure-based drug design. Inhibitors from the aminopyrazole class, such as SR-3576, were found to be very potent JNK3 inhibitors (IC(50) = 7 nm) with >2800-fold selectivity over p38 (p38 IC(50) > 20 microm) and had cell-based potency of approximately 1 microm. In contrast, indazole-based inhibitors exemplified by SR-3737 were potent inhibitors of both JNK3 (IC(50) = 12 nm) and p38 (IC(50) = 3 nm). These selectivity differences between the indazole class and the aminopyrazole class came despite nearly identical binding (root mean square deviation = 0.33 A) of these two compound classes to JNK3. The structural features within the compounds giving rise to the selectivity in the aminopyrazole class include the highly planar nature of the pyrazole, N-linked phenyl structures, which better occupied the smaller active site of JNK3 compared with the larger active site of p38.

Structure-activity relationships, and drug metabolism and pharmacokinetic properties for indazole piperazine and indazole piperidine inhibitors of ROCK-II.

ROCK has been implicated in many diseases ranging from glaucoma to spinal cord injury and is therefore an important target for therapeutic intervention. In this study, we have designed a series of 1-(4-(1H-indazol-5-yl)piperazin-1-yl)-2-hydroxy(or 2-amino) analogs and a series of 1-(4-(1H-indazol-5-yl amino)piperidin-1-yl)-2-hydroxy(or 2-amino) inhibitors of ROCK-II. SR-1459 has IC(50)=13nM versus ROCK-II while the IC(50)s for SR-715 and SR-899 are 80nM and 100nM, respectively. Many of these inhibitors, especially the 2-amino substituted analogs for both series, are modest/potent CYP3A4 inhibitors as well. However, a few of these inhibitors (SR-715 and SR-899) show strong selectivity for ROCK-II over CYP3A4, but the overall potency of the 2-amino analogs (SR-1459) on CYP3A4 and the high clearance and volume of distribution of these compounds makes the in vivo utility of these analogs undesirable.