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
.
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 A1, A2, A3 and A4 independently represent a carbon or a nitrogen, and
R3 is a group represented by the following formula:
wherein R1 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 A1, A2, A3 and A4 represents a carbon, and R3 binds to a carbon represented by A1, A2, A3 or A4.