Broad-spectrum anticonvulsants are of considerable interest as antiepileptic drugs, especially because of their potential for treating refractory patients. Such "neurostabilizers" have also been used to treat other neurological disorders, including migraine, bipolar disorder, and neuropathic pain. We synthesized a series of sulfamide derivatives (4-9, 10a-i, 11a, 11b, 12) and evaluated their anticonvulsant activity. Thus, we identified promising sulfamide 4 (JNJ-26489112) and explored its pharmacological properties. Compound 4 exhibited excellent anticonvulsant activity in rodents against audiogenic, electrically induced, and chemically induced seizures. Mechanistically, 4 inhibited voltage-gated Na(+) channels and N-type Ca(2+) channels and was effective as a K(+) channel opener. The anticonvulsant profile of 4 suggests that it may be useful for treating multiple forms of epilepsy (generalized tonic-clonic, complex partial, absence seizures), including refractory (or pharmacoresistant) epilepsy, at dose levels that confer a good safety margin. On the basis of its pharmacology and other favorable characteristics, 4 was advanced into human clinical studies.

Inhibitors of ketohexokinase (KHK) have potential for the treatment of diabetes and obesity. We have continued studies on a pyrimidinopyrimidine series of potent KHK inhibitors by exploring the 2-position substituent (R(3)) that interacts with Asp-27B in the ATP-binding region of KHK (viz. 1, 2; Table 1). We found that increased spacing between the terminal ammonium group and the heterocyclic scaffold (viz. 16-20), such that interaction with Asp-27B is not possible, still results in potent KHK inhibition (IC(50)=15-50 nM). We propose a new interaction with Asp-194, which serves to expand the pyrimidinopyrimidine pharmacophore.

Attenuation of fructose metabolism by the inhibition of ketohexokinase (KHK; fructokinase) should reduce body weight, free fatty acids, and triglycerides, thereby offering a novel approach to treat diabetes and obesity in response to modern diets. We have identified potent, selective inhibitors of human hepatic KHK within a series of pyrimidinopyrimidines (1). For example, 8, 38, and 47 exhibited KHK IC50 values of 12, 7, and 8 nM, respectively, and also showed potent cellular KHK inhibition (IC50 < 500 nM), which relates to their intrinsic potency vs KHK and their ability to penetrate cells. X-ray cocrystal structures of KHK complexes of 3, 8, and 47 revealed the important interactions within the enzyme's adenosine 5'-triphosphate (ATP)-binding pocket.

In seeking broad-spectrum anticonvulsants to treat epilepsy and other neurological disorders, we synthesized and tested a group of sulfamide derivatives (4a-k, 5), which led to the clinical development of 4a (JNJ-26990990). This compound exhibited excellent anticonvulsant activity in rodents against audiogenic, electrically induced, and chemically induced seizures, with very weak inhibition of human carbonic anhydrase-II (IC(50) = 110 microM). The pharmacological profile for 4a supports its potential in the treatment of multiple forms of epilepsy, including pharmacoresistant variants. Mechanistically, 4a inhibited voltage-gated Na(+) channels and N-type Ca(2+) channels but was not effective as a K(+) channel opener. The pharmacokinetics and metabolic properties of 4a are discussed.

We have continued to explore spirobenzazepines as vasopressin receptor antagonists to follow up on RWJ-339489 (2), which had advanced into preclinical development. Further structural modifications were pursued to find a suitable backup compound for human clinical studies. Thus, we identified carboxylic acid derivative 3 (RWJ-676070; JNJ-17158063) as a potent, balanced vasopressin V(1a)/V(2) receptor antagonist with favorable properties for clinical development. Compound 3 is currently undergoing human clinical investigation.

An improved scale-up synthesis was required for the alpha(V)beta(3)/alpha(V)beta(5) integrin antagonist 1, which had demonstrated oral efficacy in eye disease models of angiogenesis and vascular permeability. A stereodefined, quinoline-substituted, unsaturated ester was conveniently prepared by a Suzuki-Miyaura coupling to facilitate exploration of multiple methods of asymmetric reduction. The catalytic chiral hydrogenation of the corresponding unsaturated acid (Z-5b) with a ruthenium-based metal precursor and the (R)-XylPhanePhos ligand proved particularly efficient and economical. The resulting (3S)-quinoline-containing intermediate was reduced to an equal mixture of tetrahydroquinoline diastereomers. The undesired diastereomer could be recycled to the desired one by an oxidation/reduction protocol. The absolute stereochemistry of 1 was established as 3S,3'S by a combination of X-ray diffraction and chemical means.

The marketed drug topiramate ( 1) is a moderate inhibitor of carbonic anhydrase-II (CA-II) ( K i or K d = 0.3-0.6 microM), whereas sulfamide cognate 2 is a comparatively weak inhibitor ( K i or K d = 25-650 microM). From an X-ray cocrystal structure of 2.CA-II, Winum et al. ( J. Med. Chem. 2006, 49, 7024) proposed that an adverse steric interaction between the C8 methyl group in 2 and Ala-65 of CA-II is responsible for the diminished CA-II inhibitory potency of 2. We performed a straightforward test of this Ala-65 effect by synthesizing and examining ligand 3, which lacks the offending (pro- S or C8) methyl substituent in 2. We also prepared and evaluated related sulfamides 5, 7, and 9. In a CA-II inhibition assay (4-nitrophenyl acetate), the K i for 3 was approximately 300 microM, indicating very weak inhibition, close to that for 2 (4NPA, K i = 340 microM). In a CA-II binding assay (ThermoFluor), the K d for 3 was >57 microM, indicating very weak binding, lower than the affinity of 2 ( K d = 25 microM). Our results draw into question the proposed steric interaction between the C8 methyl of 2 and Ala-65 of CA-II.

We have developed a novel series of potent and selective factor Xa inhibitors that employ a key 7-fluoroindazolyl moiety. The 7-fluoro group on the indazole scaffold replaces the carbonyl group of an amide that is found in previously reported factor Xa inhibitors. The structure of a factor Xa cocrystal containing 7-fluoroindazole 51a showed the 7-fluoro atom hydrogen-bonding with the N-H of Gly216 (2.9 A) in the peptide backbone. Thus, the 7-fluoroindazolyl moiety not only occupied the same space as the carbonyl group of an amide found in prior factor Xa inhibitors but also maintained a hydrogen bond interaction with the protein's beta-sheet domain. The structure-activity relationship for this series was consistent with this finding, as the factor Xa inhibitory potencies were about 60-fold greater (DeltaDelta G approximately 2.4 kcal/mol) for the 7-fluoroindazoles 25a and 25c versus the corresponding indazoles 25b and 25d. Highly convergent synthesis of these factor Xa inhibitors is also described.

Enzyme inhibition assays often require deviations from physiological conditions. For carbonic anhydrases, procedures involving native CO(2) and non-native substrates have been used. We compared a native and a non-native substrate in the context of inhibition of human carbonic anhydrases I and II by examining various sulfamate and sulfamide compounds in two kinetic assays: hydration of CO(2) and hydrolysis of 4-nitrophenylacetate. For carbonic anhydrase II, the two assays consistently generated similar K(i) values, with the relative difference between the assays never exceeding 2.5-fold. However, for carbonic anhydrase I there was more variability between the two assays, with K(i) values for three compounds differing by more than 2.5-fold, up to eightfold. In the CO(2) hydration assay, some sulfamates and sulfamides exhibited mixed kinetics or partial inhibition. Our results indicate that K(i) or K(d) values from carbonic anhydrase assays involving non-native substrates should be confirmed by assays that use CO(2) (or HCO), to establish pharmacological relevance. From structure-activity comparisons, the sulfamate is more effective than the sulfamide in inhibiting carbonic anhydrase I and II, but the sulfamate does not confer selectivity. In contrast, the sulfonamide confers selectivity for carbonic anhydrase I (10- to 30-fold). Selectivity for carbonic anhydrase II occurred with the substituted fructose moiety, especially the d-enantiomer (>100-fold).

Compound 2 (RWJ-445167; 3DP-10017), a dual inhibitor of thrombin and factor Xa, was advanced into human clinical studies. However, its oral bioavailability in humans proved to be below acceptable limits. To address this issue, we explored a prodrug approach involving numerous guanidine derivatives. Prodrug candidates of classes A (carbamate derivatives), B (imidate derivatives), and C (alkyl and acyl derivatives), compounds 3-6, were synthesized and evaluated for anticoagulant activity at 2 h after oral administration to rats. In comparison to the parent drug (2), little worthwhile improvement was observed for the prodrug candidates.

This paper examines the relative effectiveness of bioisosteric sulfamate and sulfamide derivatives for inhibition of human carbonic anhydrase-II ( CA-II) by using a direct binding assay based on the ThermoFluor method ( Matulis et al. Biochemistry 2005, 44, 5258). Compounds 1-10, which represent five cognate sulfamate/sulfamide pairs, were studied by ThermoFluor to obtain binding affinities ( K-a values). The corresponding dissociation constants, K-d, provide an independent measure of CA-II activity relative to commonly used K-i values from enzyme kinetics studies. There was a sizable difference in potency between the sulfamates and sulfamides, with the sulfamides being much less potent, by factors ranging from 25 ( 7/8) to 1200 ( 3/4). These results are consistent with our recent report that sulfamides tend to be much weaker inhibitors of CA-II than their corresponding sulfamates ( Maryanoff et al. J. Med. Chem. 2005, 48, 1941). Additionally, for arylsulfamides 10-12 the K-d values determined by ThermoFluor and the K-i values determined from enzyme kinetics are consistent. It appears that the sulfamide group is less suitable than the sulfamate group for obtaining potent inhibition of CA-II.

This paper examines the relative effectiveness of sulfamate and sulfamide groups for the inhibition of carbonic anhydrase-II (CA-II). Topiramate (1) and its sulfamide analogue 4, and 4,5-cyclic sulfate 6 and its sulfamide analogue 5, were compared for inhibition of human CA-II. A colorimetric assay, based on the pH shift that accompanies hydration of carbon dioxide, and an esterase assay were used. For these bioisosteric pairs, 1/4 and 6/5, the sulfamate compound was markedly more potent than its sulfamide counterpart. A similar, large difference in potency was also observed for the sulfamate/sulfamide pairs 14/15 and 16/17. These results indicate that the sulfamide moiety is not particularly suitable for obtaining potent carbonic anhydrase inhibition. A discussion of this structure-activity relationship with respect to the interactions of 1 and 6 with CA-II from published X-ray data is presented. A metabolic acidosis study was performed in rats with 1, 4, 6, and 2, and the results are discussed with respect to the degree of inhibition of CA-II in vivo.