8-Hyroxy-2-Dipropylaminotetralin Hydrobromide (8-OH-DPAT) is a chemical predominantly used in research settings. It is widely regarded as the first identified complete agonist of the 5-HT1a receptor, for which it has a Ki = 3.18 nM. 8-OH-DPAT also acts as an agonist of the 5-HT7 receptor, and as a substrate of the Sodium dependent serotonin transporter (SERT). Although it has never progressed to human clinical trials 8-OH-DPAT has been studied in animal models for a number of conditions both for its own potential and as a benchmark for other compounds.

BRL-15572 is a 5-HT1D receptor antagonist with pKi of 7.9, also shows a considerable affinity at 5-HT1A and 5-HT2B receptors, exhibiting 60-fold selectivity over 5-HT1B receptor.

BMS-442606 is an S-enantiomer of 6-hydroxybuspirone and is a 5-HT1A partial agonist. BMS-442606 has advantage of being cleared more slowly from blood compared to the R-enantiomer, but R form showed higher affinity and selectivity for the 5HT1A receptor compared to the S-isomer. Because both isomers together with racemic form were well tolerated and was not found any advantage of one of the enantiomers of over the racemic form. Finally, racemic form was chosen for further clinical development.

N-Methylquipazine is a tertiary amine analog of quipazine. It binds at 5-HT3 sites with an affinity similar to that of quipazine. N-methylquipazine has a low affinity for 5-HT1A, 5-HT1B, 5-HT2, a1, a2 and muscarinic receptors. It produces a concentration-dependent increase in extracellular dopamine levels in the anterior medial prefrontal cortex. This action is dependent on the presence of Ca+2, is impulse-dependent, and depends on newly synthesized dopamine stores. The increase in the anterior medial prefrontal cortex dopamine levels by n-methylquipazine is probably, not mediated by its interaction with the 5-HT3 receptor. It might be an be an attractive candidate as a radioligand for the PET studies of 5-HT3 receptors in man.

Lespedin (Kaempferitrin) is extracted in significantly high quantities from the leaves of Cinnamomum osmophloeum (C.O) and Bauhinia forficata, and are used as an antidiabetic herbal remedy in China and Brazil. Commercial product using dry Cinnamomum osmophloeum leaves has been sold locally in Taiwan. Oral administration of kaempferitrin reduced blood sugar in diabetic rats. Lespedin possessed significant antiosteoporotic activity. Combined with its limited estrogen-like side effect, Lespedin can be regarded as an idealistic antiosteoporotic candidate for human osteoporosis diseases. Kaempferitrin was found to have an acute lowering effect on blood glucose in diabetic rats and to stimulate the glucose uptake percentile, as efficiently as insulin in muscle from normal rats.

Canadine (tetrahydroberberine,THB) is an isoquinoline alkaloid (5,8,13,13a-tetrahydro-9,10-dimethoxy-6H-benzo[g]-1,3-benzodioxolo[5,6-a]quinolizine) from Corydalis tuber, it has micromolar affinity for dopamine D(2) (pK(i) = 6.08) and 5-HT(1A) (pK(i) = 5.38) receptors but moderate to no affinity for other relevant serotonin receptors (i.e., 5-HT(1B), 5-HT(1D), 5-HT(3), and 5-HT(4). Canadine enhances gastrointestinal motor function. THB, with D(2) receptor antagonist and 5-HT(1A) receptor agonist properties, has significant potential as a therapeutic for treatment of functional dyspepsia. THB is a potent inhibitor of platelet aggregation in vitro and in vivo and is a promising antithrombotic drug.

5-carboxamidotryptamine (5-CT) is a 5-HT1 agonist with high affinity at 5-HT1A, 5-HT1B, 5-HT1D, 5-HT5 and 5-HT7 receptors. As one of the first compounds reported active at 5-HT1B, 5-carboxamidotryptamine was originally investigated as a potential treatment for migraine. During preclinical studies, 5-CT was found to cause vasodilatation of carotid circulation and hypotension in animals, effects that were later attributed to potent agonist activity at 5-HT7. Subsequent structural modifications of 5-CT led to the discovery of the anti-migraine drug sumatriptan. 5-CT is primarily used as a pharmacological tool for study of 5-HT1 and 5-HT7 mediated functional responses.