Inhibitor of the Tyrosine Phosphatase STEP Reverses Cognitive Deficits in a Mouse Model of Alzheimer's Disease
(A) Commercially purchased Compound 3 was dissolved in methanol at 10 mg/mL, and 300 µL portions were injected onto a Zorbax (Agilent) 5 µm 300SB-C18 column (0.94×25 cm, 3 mL/min 75% methanol/25% pH 4.0 0.1 M ammonium acetate). Thirty-five fractions (3 mL each) were collected, evaporated, and reconstituted in 100 µL of DMSO. Fractions were tested with pNPP assays to determine inhibition of STEP activity by using 0.1 µL of each fraction and 100 nM of STEP protein in 96-well plates. DMSO alone was used as a control. Shown in the insert is a representative chromatogram (UV absorbance detection, 350 nm). Peaks A, B, and C indicate early unretained material, Compound 3, and the unknown compound. (B) Structure of S8, the benzopentathiepin core, and 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (known as TC-2153). (C and D) Dose–response curves for S8 and TC-2153. (C) The IC50 for S8 was determined to be 17.2±0.4 nM (mean ± s.e.m., n = 4). (D) The IC50 for TC-2153 was determined to be 24.6±0.8 nM (mean ± s.e.m., n = 4).