Melatonin-Tamoxifen Conjugate (compound 16c) is an anticancer drug conjugate composed of Melatonin and Tamoxifen, which is a potent antagonist of ERα (IC50=863 nM). Melatonin-Tamoxifen Conjugate binds to MLT receptor (Ki=3.1 nM) and promotes β-arrestin (EC50=914 nM) and ERK activation (EC50=98 nM) in cells expressing hMT1 receptor. Melatonin-Tamoxifen Conjugate against several common cell lines MCF-7, MDA-MB-231, and HT-1080 with IC50s of 6.8 μM, 6.4 μM, and 1.7 μM, respectively.

DH97 is a potent melatonin receptor 2 (MT2) antagonist with Ki values of 252 nM and 1100 nM for MT2 and MT1, respectively.

(R)-Ramelteon ((R)-TAK-375) is an orally active inactive isomer of the melatonin receptor 1 and 2. (R)-Ramelteon is promising for research of regulating sleep.

4-P-PDOT is a slelctive MT2 melatonin receptor antagonist 300 fold selective for MT2 (MEL-1B-R) vs MT1 (MEL-1A-R) melatonin receptor subtype.

Luzindole (N-0774) is a selective melatonin receptor antagonist. Luzindole preferentially targets MT2 (Mel1b) over MT1 (Mel1a) with Ki values of 10.2 and 158 nM for human MT2 and MT1, respectively. Luzindole suppresses experimental autoimmune encephalomyelitis (EAE), and exerts antidepressant-like activity.

N-Acetyltryptamine is a partial agonist for melatonin receptors in the retina. N-Acetyltryptamine is also used for determination of serotonin N-acetyl transferase activity.

4P-PDOT, also known as 4-phenyl-2- propionamidotetralin, is a MT2-receptor-specific antagonist. MT2 melatonin receptor may be a novel target for analgesic drug development.

S-22153 is a potent melatonin receptor antagonist with EC50 values of 19 nM, 4.6 nM for hMT1 and hMT2 melatonin receptor, respectively. S-22153 has Ki values of 8.6 nM (CHO cells) and 16.3 nM (HEK cells) for hMT1, and 6.0 nM (CHO cells) and 8.2 nM (HEK cells) for hMT2. S-22153 is a specific ligand of MT1 and MT2 melatonin receptors subtypes.

DH97 is a potent and selective antagonist of MT2 melatonin receptor, with a pKi of 8.03 for human MT2. DH97 shows 89- and 229-fold selectivity for human MT2 over human mt1 and Xenopus mel1c receptor subtypes. DH97 can inhibit melatonin-induced enhancement of electrically-evoked responses.

UCM 608 is a high affinity melatonin (MT) membrane receptor agonist. The pKi values for MT1 and MT2 are 10.7 and 10.4.

6-Chloromelatonin is a potent melatonin receptor agonist with greater metabolic stability than melatonin. 6-Chloromelatonin compete for [3H]-melatonin and 2-[125I]-iodomelatonin binding to MT1 receptors (pKi=8.9 and 9.1, respectively). 6-Chloromelatonin compete for [3H]-melatonin binding to MT2 receptors (pKi=9.77).

7-Desmethyl-3-hydroxyagomelatine (3-Hydroxy-7-desmethyl agomelatine), a metabolite of Agomelatine, has less activity than Agomelatine. Agomelatine is a melatonergic (MT1 and MT2) agonist and serotonergic (5HT2C) antagonist.

S26131 (compound 5) is a potent and selective MT1 melatoninergic ligand, and the Ki values are 0.5 and 112 nM for MT1 and MT2, respectively. S26131 behaves as an MT1 and MT2 antagonist.

8-M-PDOT (AH-002) is a selective melatonin MT2 receptor agonist. 8-M-PDOT is 5.2-fold selective for MT2 over MT1 receptors. 8-M-PDOT binds human recombinant MT2 and MT2 receptors with pKi values of 8.23 and 8.95 respectively. 8-M-PDOT has anxiolytic-like activity.

2-Iodomelatonin is a potent agonist of melatonin receptor 1 (MT1) with a Ki value of 28 pM, it is more 5-fold selective for MT1  over MT2. 2-iodomelatonin can be used to identify, characterize and localize melatonin binding sites in the brain and peripheral tissues.

Ramelteon is a novel melatonin receptor agonist for human MT1 and MT2 receptors and chick forebrain melatonin receptors with Ki of 14 pM, 112 pM and 23.1 pM, respectively.

Agomelatine is classified as a norepinephrine-dopamine disinhibitor (NDDI) due to its antagonism of the 5-HT2C receptor.