Novel compound having affinity to amyloid

Abstract

The invention relates to a compound which has affinity with amyloid, shows sufficiently rapid clearance from normal tissues and is suppressed in toxicity such as mutagenicity, and also relates to a low-toxic diagnostic agent for Alzheimer's disease containing the compound. The compound is represented by the following formula (1) or a salt thereof: wherein A 1 , A 2 , A 3 and A 4 independently represent a carbon or a nitrogen, and R 3 is a group represented by the following formula: wherein R 1 is a radioactive halogen substituent; m is an integer of 0 to 4; and n is an integer of 0 or 1, provided that at least one of A 1 , A 2 , A 3 and A 4 represents a carbon, and R 3 binds to a carbon represented by A 1 , A 2 , A 3 or A 4 .

1 - 8 . (canceled) 
     
     
         9 . A low-toxic diagnostic agent for Alzheimer's disease, which comprises a compound represented by the following formula (1) or a salt thereof: 
       
         
           
           
               
               
           
         
         wherein A 1 , A 2 , A 3  and A 4  independently represents a carbon or a nitrogen, and 
         R 3  is a group represented by the following formula: 
       
       
         
           
           
               
               
           
         
         wherein R 1  is a radioactive halogen substituent; 
         m is an integer of 0 to 4; and 
         n is an integer of 0 or 1, 
         provided that at least one of A 1 , A 2 , A 3  and A 4  represents a carbon and R binds to a carbon represented by A 1 , A 2 , A 3  or A 4 . 
       
     
     
         10 . A low-toxic diagnostic agent for Alzheimer's disease according to  claim 9 , wherein at least three of A 1 , A 2 , A 3  and A 4  represent carbons. 
     
     
         11 . A low-toxic diagnostic agent for Alzheimer's disease according to  claim 10 , wherein all of A 1 , A 2 , A 3  and A 4  represent carbons. 
     
     
         12 . A low-toxic diagnostic agent for Alzheimer's disease according to  claim 9 , wherein R 1  is selected from the group consisting of  18 F,  76 Br,  123 I,  124 I,  125 I and  131 I.