USE OF N-(4-ISOPROPYLPHENYL)-5-AMINO-ISOINDOLINE

Abstract

The present invention relates to a novel use of N-(4-isopropylphenyl)-5-amino-isoindoline for diagnosing Alzheimer's disease and quantifying amyloid in the brain.

Claims

1. Use of N-(4-isopropylphenyl)-5-amino-isoindoline represented by Formula (1) below for diagnosing Alzheimer's disease: ##STR00002##

2. The use according to claim 1, wherein the liposolubility of N-(4-isopropylphenyl)-5-amino-isoindoline is higher than 2.

3. The use according to claim 1, wherein the N-(4-isopropylphenyl)-5-amino-isoindoline is able to bind to amyloid.

4. The use according to any one of claims 1 to 3 for quantifying amyloid in the brain.

5. The use according to any one of claims 1 to 3, wherein the N-(4-isopropylphenyl)-5-amino-isoindoline is marked with a radioactive element.

6. The use according to claim 5, wherein the radioactive element is C-11 or F-18.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 shows the result of the compound of the present invention competing with the amyloid florescent dye ThT for binding to A40 in the example.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

[0018] The N-(4-isopropylphenyl)-5-amino-isoindoline in the present invention (referred to as the compound of the present invention sometime) is screened out for its ability to bind to -amyloid by molecular docking, binding pattern simulation, and in-vitro binding assay. The screening method is detailed now.

[0019] Structure-based drug design plays a very important role in the development of drugs. During the exertion of a drug efficacy, the drug molecule needs to be adequately close to the target, assumes a suitable orientation, and interacts with the target by appropriately adjusting the conformation, to form a stable complex. The structure-based drug design is achieved mainly by molecular docking. Molecular docking is one of the important molecular simulation methods, by which the interaction between the ligand and the receptor can be simulated according to the lock and key principle underlying the interaction between the ligand and receptor. The molecular recognition process involves hydrogen bonding, electrostatic interaction, hydrophobic interaction and van der Waals force. The binding pattern and affinity therebetween are predicted by computer simulation, to carry out the screening of virtual drugs. The two critical factors in molecular docking are intermolecular spatial and energy complementary, wherein the spatial identification is the intermolecular geometrical pairing, to seek the best interaction pattern between the ligand and the receptor, and the energy identification is used for evaluating the binding stability. Molecular docking is widely used for searching small molecules that have a good affinity to the receptor from a small molecule database, and then the small molecules are subjected to pharmacological test, to screen out potential lead compounds.

[0020] The software for screening the drugs is Discovery Studio 3.0 (Accelrys Inc., USA), in which the orientation of binding of the small molecular compound to the -amyloid receptor is simulated by using the molecular docking CDOCKER module, and the CDOCKER uses a CHARMm-based docking technique and a pattern in which the receptor adopts a fixed conformation and the ligand adopts a flexible conformation, to evaluate the most stable orientation of binding. The compound of the present invention is screened out by (1) molecular docking; and (2) analysis of orientation of binding. After the compound of the present invention is screened out, the ability of the compound to bind to the -amyloid receptor is confirmed by in-vitro binding assay.

[0021] The screening is performed by computer software and thus is not detailed in the present invention.

[0022] The method for assaying the ability of the compound of the present invention to bind to -amyloid receptor is described by way of example below. However, the example is provided merely for illustrating, instead of limiting the scope of the present invention.

Example

[0023] In-Vitro Assay

[0024] Competition for fluorescent binding to A40: the inhibition test of competition binding to amyloid was carried out, in which 2 M A40, 1 M amyloid fluorescent dye ThT, and 0.47 nM, 0.94 nM, 4.7 nM, 9.4 nM, 47 nM, 94 nM, 470 nM, 940 nM, 4700 nM and 9400 nM of standard compounds (PiB and BTA-1) and the compound of the present invention as the competing compounds were used. The reaction was carried out for 2 hrs at room temperature, which was excited by using Anthos Zenyth 3100 at an excitation wavelength of 485 nm, and then emitted a florescence of 535 nm. The binding rate of ThT to amyloid was set to 1 where no compound of the present invention was added to compete with ThT for binding. The PiB and BTA-1 were used as positive controls, and the binding rate of each concentration of compound was calculated according to the formula: binding rate =(fluorescence intensity with the compound of the present invention/fluorescence intensity without the compound of the present invention). The result is shown in FIG. 1, in which the horizontal axis is the concentration of the competing compound, and the longitudinal axis is the binding rate of ThT. It can be known from the result shown in the figure that when the concentration of the competing compound is gradually increased, the binding rate of the fluorescent dye ThT is observed to decrease gradually with the increasing concentration of the compound of the present invention, which means that the fluorescent dye ThT binding to amyloid is replaced such that the fluorescence intensity is lowered, demonstrating that the compound of the present invention can well bind to -amyloid. Also, it can be known from FIG. 1 that compared with PiB and BTA-1 known to have high affinity to -amyloid, the compound of the present invention has a ThT binding rate comparable to that of other known compounds at a low concentration.

[0025] It can be known from the result above that due to the ability to well bind to -amyloid, the compound of the present invention is anticipated to be one of the tools for detecting AD in vivo that is useful for diagnosing Alzheimer's disease and quantifying amyloid in the brain, thus being of great significance in medical industry.