George L. Trainor

MEK inhibitors: the chemistry and biological activity of U0126, its analogs, and cyclization products.

In search of antiinflammatory drugs with a new mechanism of action, U0126 was found to functionally antagonize AP-1 transcriptional activity via noncompetitive inhibition of the dual specificity kinase MEK with an IC50 of 0.07 microM for MEK 1 and 0.06 microM for MEK 2. U0126 can undergo isomerization and cyclization reactions to form a variety of products, both chemically and in vivo, all of which exhibit less affinity for MEK and lower inhibition of AP-1 activity than parent, U0126.

The discovery of 4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-pyrazolo-[1,5-a]-pyrimidine: A corticotropin-releasing factor (hCRF1) antagonist

Structure activity relationship studies led to the discovery of 4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-pyrazo lo-[1,5-a]-pyrimidine 11-31 (DMP904), whose pharmacological profile strongly supports the hypothesis that hCRF1 antagonists may be potent anxiolytic drugs. Compound 11-31 (hCRF1 Ki = 1.0+/-0.2 nM (n = 8)) was a potent antagonist of hCRF1-coupled adenylate cyclase activity in HEK293 cells (IC50= 10.0+/-0.01 nM versus 10 nM r/hCRF, n = 8); alpha-helical CRF(9-41) had weaker potency (IC50 = 286+/-63 nM, n = 3). Analogue 11-31 had good oral activity in the rat situational anxiety test; the minimum effective dose for 11-31 was 0.3 mg/kg (po). Maximal efficacy (approximately 57% reduction in latency time in the dark compartment) was observed at this dose. Chlordiazepoxide caused a 72% reduction in latency at 20 mg/kg (po). The literature compound 1 (CP154526-1, 30 mg/kg (po)) was inactive in this test. Compound 11-31 did not inhibit open-field locomotor activity at 10, 30, and 100 mg/kg (po) in rats. In beagle dogs, this compound (5 mg/kg, iv, po) afforded good plasma levels. The key iv pharmacokinetic parameters were t1/2, CL and Vd,ss values equal to 46.4+/-7.6 h. 0.49+/-0.08 L/kg/h and 23.0+/-4.2 L/kg, respectively. After oral dosing, the mean Cmax, Tmax t1/2 and bioavailability values were equal to 1260+/-290 nM, 0.75+/-0.25 h. 45.1+/-10.2 h and 33.1%, respectively. The overall rat behavioral profile of this compound suggests that it may be an anxiolytic drug with a low motor side effect liability.

Quinazolines as cyclin dependent kinase inhibitors.

Quinazolines have been identified as inhibitors of CDK4/D1 and CDK2/E. Aspects of the SAR were investigated using solution-phase, parallel synthesis. An X-ray crystal structure was obtained of quinazoline 51 bound in CDK2 and key interactions within the ATP binding pocket are defined.

Synthesis and evaluation of analogs of Efavirenz (SUSTIVATM) as HIV-1 reverse transcriptase inhibitors

Abstract Efavirenz (SUSTIVA TM ) is a potent non-nucleoside reverse transcriptase inhibitor. Due to the observation of breakthrough mutations of the reverse transcriptase enzyme during Efavirenz therapy, we sought to develop an optimized second generation series. To that end, SAR of the substituents on the aromatic ring was undertaken and the results are summarized here. The 5,6-difluoro ( 4f ) and the 6-methoxy ( 4m ) substituted benzoxazinones were determined to be equipotent, and as a result such substitution patterns will be incorporated in second generation scaffolds.

Preclinical antitumor efficacy of analogs of XK469: sodium-(2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]propionate

A series of quinoxaline analogs of the herbicide Assure® was found to have selective cytotoxicity for solid tumors of mice in a disk-diffusion-soft-agar-colony-formation-assay compared to L1210 leukemia. Four agents without selective cytotoxicity and 14 agents with selective cytotoxicity were evaluated in vivo for activity against a solid tumor. The four agents without selective cytotoxicity in the disk-assay were inactive in vivo (T/C > 42%). Thirteen of the fourteen agents with selectivity in the disk-assay were active in vivo (T/C < 42%). Five of the agents had curative activity. These five agents had a halogen (F, Cl, Br) in the 7-position (whereas Assure® had a Cl in the 6 position). All agents with curative activity were either a carboxylic acid, or a derivative thereof, whereas Assure® is the ethyl ester of the carboxylic acid. All other structural features were identical between Assure® and the curative agents. Assure® had no selective cytotoxicity for solid tumors in the disk-assay, and was devoid of antitumor activity. The analog XK469 is in clinical development.

Synthesis and evaluation of benzoxazinones as HIV-1 reverse transcriptase inhibitors. Analogs of Efavirenz (SUSTIVATM)

Two series of benzoxazinones differing in the aromatic substitution pattern were prepared and evaluated as HIV-1 reverse transcriptase inhibitors. The 5-fluoro (5a-d) and 6-nitro (5e-h) substituted compounds displayed activity comparable or better than Efavirenz, the lead structure of the series.

Synthesis and Evaluation of Efavirenz (SustivaTM) Analogues as HIV-1 Reverse Transcriptase Inhibitors: Replacement of the Cyclopropylacetylene Side Chain

Two series of efavirenz analogues have been developed: one in which the cyclopropane ring has been replaced by small heterocycles and another in which the entire acetylenic side chain has been replaced by alkyloxy groups. Several members of both series show equivalent potency to efavirenz against both wild-type virus and the key K103N mutant.

Helicobacter pylori-selective antibacterials based on inhibition of pyrimidine biosynthesis.

We report the discovery of a class of pyrazole-based compounds that are potent inhibitors of the dihydroorotate dehydrogenase of Helicobacter pylori but that do not inhibit the cognate enzymes from Gram-positive bacteria or humans. In culture these compounds inhibit the growth of H. pylori selectively, showing no effect on other Gram-negative or Gram-positive bacteria or human cell lines. These compounds represent the first examples of H. pylori-specific antibacterial agents. Cellular activity within this structural class appears to be due to dihydroorotate dehydrogenase inhibition. Minor structural changes that abrogate in vitro inhibition of the enzyme likewise eliminate cellular activity. Furthermore, the minimum inhibitory concentrations of these compounds increase upon addition of orotate to the culture medium in a concentration-dependent manner, consistent with dihydroorotate dehydrogenase inhibition as the mechanism of cellular inhibition. The data presented here suggest that targeted inhibition of de novo pyrimidine biosynthesis may be a valuable mechanism for the development of antimicrobial agents selective for H. pylori.

Synthesis and evaluation of quinoxalinones as HIV-1 reverse transcriptase inhibitors

A series of 3,3-disubstituted quinoxalinones was prepared and evaluated as HIV-1 reverse transcriptase inhibitors. The N-allyl (6b and 6f), N-cyclopropylmethyl (6a, 6g, 6h, and 6k) and N-carboalkoxy (6m-6y) substituted compounds displayed activity comparable or better than Efavirenz and GW420867X.

Identification of selective inhibitors of cyclin dependent kinase 4

A new structural type of kinase inhibitor, containing a benzocarbazole nucleus, has been identified. Members of the series are selective for inhibition of the cyclin dependent kinase family of enzymes. Although the cdks are highly homologous, representatives of the series showed intra-cdk selectivities, especially for cdk4. SAR studies elucidated the important features of the molecules for inhibition.