New alpha-substituted succinate-based hydroxamic acids as TNFalpha convertase inhibitors.

Tumor necrosis factor alpha convertase (TACE), the enzyme responsible for the processing of pro-TNFalpha to TNFalpha, has been reported to be a metalloproteinase closely related to matrix metalloproteinases (MMPs). Current inhibitors of TACE such as succinate-based hydroxamic acids exemplified by Marimastat (TACE IC(50): 3.8 nM; blood IC(50): 7 microM) and BB1101 (TACE IC(50): 0.2 nM; blood IC(50): 2.3 microM) suffer from modest potency in blood and poor in vivo properties. The introduction of new bulky alpha-substituents into these succinate-based hydroxamic acids was studied. Substituents such as thioethers, sulfonamides, and ethers showed improved potency against TACE when compared with Marimastat. Although this improvement did not translate into better blood potency for thioether or ether substituents, the sulfonamide series exhibited improved potency both against TACE and in blood when compared with Marimastat. Optimization of this sulfonamide series has culminated in the identification of heterocyclic bicyclic sulfonamides such as 3t (TACE IC(50): 0.57 nM; blood IC(50): 0.28 microM).

Design and structure-activity relationship of a new class of potent VEGF receptor tyrosine kinase inhibitors.

A series of substituted 4-anilinoquinazolines and related compounds were synthesized as potential inhibitors of vascular endothelial growth factor (VEGF) receptor (Flt and KDR) tyrosine kinase activity. Enzyme screening indicated that a narrow structure-activity relationship (SAR) existed for the bicyclic ring system, with quinazolines, quinolines, and cinnolines having activity and with quinazolines and quinolines generally being preferred. Substitution of the aniline was investigated and clearly indicated that small lipophilic substituents such as halogens or methyl were preferred at the C-4' position. Small substituents such as hydrogen and fluorine are preferred at the C-2' position. Introduction of a hydroxyl group at the meta position of the aniline produced the most potent inhibitors of Flt and KDR tyrosine kinases activity with IC(50) values in the nanomolar range (e.g. 10, 12, 13, 16, and 18). Investigation of the quinazoline C-6 and C-7 positions indicates that a large range of substituents are tolerated at C-7, whereas variation at the C-6 is more restricted. At C-7, neutral, basic, and heteroaromatic side chains led to very potent compounds, as illustrated by the methoxyethoxy derivative 13 (IC(50) < 2 nM). Our inhibitors proved to be very selective inhibitors of Flt and KDR tyrosine kinase activity when compared to that associated with the FGF receptor (50- to 3800-fold). Observed enzyme profiles translated well with respect to potency and selectivity for inhibition of growth factor stimulated proliferation of human umbilical vein endothelial cells (HUVECs). Oral administration of selected compounds to mice produced total plasma levels 6 h after dosing of between 3 and 49 microM. In vivo efficacy was demonstrated in a rat uterine oedema assay where significant activity was achieved at 60 mg/kg with the meta hydroxy anilinoquinazoline 10. Inhibition of growth of human tumors in athymic mice has also been demonstrated: compound 34 inhibited the growth of established Calu-6 lung carcinoma xenograft by 75% (P < 0.001, one tailed t-test) following daily oral administration of 100 mg/kg for 21 days.

Conformational analysis of 5-lipoxygenase inhibitors: role of the substituents in chiral recognition and on the active conformations of the (methoxyalkyl)thiazole and methoxytetrahydropyran series.

The investigation of the SAR of 5-lipoxygenase (5-LO) inhibition of a series of racemic (methoxyalkyl)thiazoles, exemplified by compound 7 (ZM-211965), has led to other active, racemic derivatives in which the thiazole moiety has been replaced by an ester or an ether. Furthermore, the cyclization of the ethers has given a highly potent, but achiral series, the methoxytetrahydropyrans (methoxyTHP), exemplified by 41 (ZD-2138) presently under clinical evaluation. More recent structural investigations have led to chiral members of this series bearing a 2-methyl substituent in the tetrahydropyran ring. The potential for enantioselectivity in each of the three noncyclic, racemic series led us to synthesize the pure enantiomers ((R)-13c, (S)-13c, (R)-13d, (S)-13d, (R)-15c, (S)-15c, (R)-16b, (S)-16b, and (R)-16c, (S)-16c) and to determine their absolute configuration. The biological activity of each enantiomer was evaluated in intact mouse macrophages and in human whole blood and showed that, of these three series, only the thiazole is enantioselective and that the active configuration is (S) (being between 2 and 3 orders of magnitude more potent than the (R) isomer in mouse macrophages). Conformational analysis using systematic conformational searching, molecular mechanics, and semiempirical methods has been performed on the chiral compounds, and the results have helped to explain the enantioselectivity in the thiazole series and to define the role of the substituents around the quaternary carbon. Simultaneously in the achiral tetrahydropyran (THP) series, the critical role of the methoxy substituent has been examined through the synthesis of the ethyl (24b), ester (22b), methoxymethyl ether (26), hydroxymethyl (25b), aldehyde (27b), ketone (29b), hydroxy (31b), and methyl (23b) analogues and by analysis of their biological and conformational properties. This approach, complemented by the results of a similar study carried out on the Z and E isomers of the chiral ethyl-2-methylTHP derivative (39b and 40b), has also led to the characterization of the active conformation in this series. The whole study has identified new elements to clarify the 3D structural requirements of the 5-LO active site.