AR-A 2 is a selective 5-HT1B receptor antagonist, with high affinity to guinea pig cortex 5HT1B/1D and recombinant guinea pig 5-HT1B receptors (Ki=0.24 and 0.47 nM) and with 10-fold lower affinity to guinea pig 5-HT1D receptor (Ki, 5 nM), and shows an EC50 of 4.5 nM for the guinea pig 5-HT1B receptor; AR-A 2 can be used in the research of depression and anxiety. AR-A 2 (AR-A000002) is a selective 5-HT1B receptor antagonist, with high affinity to guinea pig cortex 5HT1B/1D and recombinant guinea pig 5-HT1B receptors (Ki=0.24 and 0.47 nM) and with 10-fold lower affinity to guinea pig 5-HT1D receptors (Ki, 5 nM), and shows an EC50 of 4.5 nM for the guinea pig 5-HT1B receptor. AR-A 2 also binds to the rat cortical 5HT1B/1D receptor (Ki, 20 nM), rat cortex 5-HT2A receptor (Ki, 339 nM), rat hippocampus 5-HT1A receptor (Ki, 3070 nM). In addition, AR-A 2 also exhibits affinity for dopamine D2 (Ki, 330 nM) and α1-adrenoceptors (Ki, 490 nM).