A compound that has affinity with amyloid, exhibits sufficiently rapid clearance from normal tissues, and is suppressed in toxicity such as mutagenicity is provided, which is represented by the following formula (1):
or a salt thereof,
wherein R
1
is a group selected from hydrogen, hydroxyl group, carboxyl group, sulfate group, amino group, nitro group, cyano group, an alkyl substituent with one to 4 carbon atoms or an alkoxy substituent with one to 4 carbon atoms; R
2
is a radioactive halogen substituent; and m is an integer of 0 to 2, and a low-toxic diagnostic agent for Alzheimer's disease comprising a compound represented by the above formula or a salt thereof is also provided.
A compound effective as a probe targeting amyloid for image diagnosis and a reagent comprising the compound for detecting amyloid deposited on a biological tissue are provided. Provided are a compound represented by the following formula (1):
wherein R
1
is a group selected from the group consisting of a halogen substituent, alkyl substituent with 1 to 4 carbon atoms, alkoxy substituent having alkyl chain with 1 to 4 carbon atoms and hydroxyl group, R
2
is a group selected from the group consisting of a cyano substituent, alkyl substituent with 1 to 4 carbon atoms and halogen substituent, R
3
is a group selected from the group consisting of a hydroxyl group, halogen substituent and substituent represented by the following formula:
(wherein R
4
is a hydrogen, halogen substituent or hydroxyl group, and m is an integer of 1 to 4), provided that at least one of R
1
, R
2
, R
3
and R
4
represents a radioactive halogen, and a reagent comprising the same.