Michael A. Pleiss

Discovery of sulfonamide–pyrazole γ-secretase inhibitors

Utilizing a pharmacophore hypothesis, previously described gamma-secretase inhibiting HTS hits were evolved into novel tricyclic sulfonamide-pyrazoles, with high in vitro potency, good brain penetration, low metabolic stability, and high clearance.

Discovery of a potent, orally bioavailable pyrimidine VLA-4 antagonist effective in a sheep asthma model

A series of N-(pyrimidin-4-yl)-phenylalanine VLA-4 antagonists is described. Optimization of substituents at the 2 and 5 positions of the pyrimidine ring gave 14, a very potent VLA-4 inhibitor which is orally active in a sheep asthma model.

Gas chromatographic quantitation of underivatized amines in the determination of their octanol-0.1 M sodium hydroxide partition coefficients by the shake-flask method.

The use of gas chromatography (GC) for the determination of 0.1 M sodium hydroxide-octanol partition coefficients (log P) for a wide variety of ethylamines is demonstrated. The conventional shake-flask procedure (SFP) is utilized, with the addition of an internal reference, which is cleanly separated from the desired solute and solvents on a 10% Apiezon L, 2% potassium hydroxide on 80-100 mesh Chromosorb W AW column. The partitioned solute is extracted from the aqueous phase with chloroform and analyzed by GC. The method provides an accurate and highly reproducible means of determining log P values, as demonstrated by the low relative standard errors. The technique is both rapid and extremely versatile. The use of the internal standard method of analysis introduces consistency, since variables like the exact weight of solute are not necessary (unlike the traditional SFP) and the volume of sample injected is not critical. The technique is readily accessible to microgram quantities of solutes, making it ideal for a wide range of volatile, amine-bearing compounds.

Conformational preferences of dopamine analogues for inhibition of norepinephrine N-methyltransferase. Conformationally defined adrenergic agents. 7☆

A series of analogues of dopamine (DA) with varying degrees of conformational flexibility have been examined as potential substrates or competitive inhibitors of the enzyme norepinephrine N-methyltransferase (NMT). A conformationally defined (rigid) analogue of the fully extended conformation of DA, 2-amino-6,7-dihydroxybenzonorbornene hydrobromide (3; 6,7-D2HX) proved to be a better substrate than the non-catechol parent 2-aminobenzonorbornene (4; 2HX). However, analogues 3 and 4 displayed equivalent competitive inhibitory activity toward phenylethanolamine (PEA). Neither 6,7-ADTN (5), a DA analogue in the 2-aminotetralin (2AT) system, nor 6,7-DTHIQ (7), a DA analogue in the tetrahydroisoquinoline (THIQ) system, showed substrate activity; 6,7-ADTN was a poorer competitive inhibitor than the parent 2AT but 6,7-DTHIQ was a better competitive inhibitor than its parent, THIQ (8). A tricyclic conformationally defined analogue 9 of 6,7-ADTN was devoid of either substrate or inhibitory activity. From these results it may be concluded that a fully extended side chain conformation is required for NMT substrate activity, and the better substrate activity for 6,7-D2HX compared to 4 is consistent with a proper catechol orientation for interaction with the norepinephrine (NE) binding site of NMT.

Orally available and efficacious α4β1/α4β7 integrin inhibitors.

A series of potent α4β1/α4β7 integrin inhibitors is reported, including an inhibitor 12d with remarkable oral exposure and efficacy in rat models of rheumatoid arthritis and Crohns disease.

Arylsulfonamide pyrimidines as VLA-4 antagonists

A series of (S)-2-(2-(diethylamino)-5-(N-alkyl-N-sulfonamido)pyrimidin-4-ylamino)-3-(4-(carbamoyloxy)phenyl)propanoic acid is discovered as orally available VLA-4 antagonists. Representative compounds 11b and 11p showed efficacy in multiple in vivo animal models. The in vitro selectivity of 11p is also described.

PEG conjugates of potent α4 integrin inhibitors, maintaining sustained levels and bioactivity in vivo, following subcutaneous administration.

Mitsunobu reactions were employed to link t-butyl esters of α4 integrin inhibitors at each of the termini of a three-arm, 40 kDa, branched PEG. Cleavage of the t-butyl esters using HCO2H provided easily isolated PEG derivatives, which are potent α4 integrin inhibitors, and which achieve sustained levels and bioactivity in vivo, following subcutaneous administration to rats.

Amino-caprolactam γ-secretase inhibitors showing potential for the treatment of Alzheimer’s disease

Herein we describe the structure-activity relationship (SAR) of amino-caprolactam analogs derived from amino-caprolactam benzene sulfonamide 1, highlighting affects on the potency of γ-secretase inhibition, selectivity for the inhibition of APP versus Notch processing by γ-secretase and selected pharmakokinetic properties. Amino-caprolactams that are efficacious in reducing the cortical Aβ(x-40) levels in FVB mice via a single 100 mpk IP dose are highlighted.