In contrast to the classic so-called “hypnotic drugs” (eg, benzodiazepines, barbiturates, zopiclone, and Zolpidem), melatonin does not have direct, hypnotic properties related to its chemical structure. Its hypnotic effects depend on the activity of NAT in the CNS. Melatonin: a bioprecursor of hypnotic metabolites During the development of the GC-MS method for the assay of melatonin in plasma,2 our attention was focussed on the chemical reactivity of melatonin at position 3, which allows cyciization of the side chain after acylation. Inhibitors,research,lifescience,medical This proceeds by nucleophilic attack

and leads to a fluoroacyl-β-carboline (Figure 4). Figure 4. Perfluoroacylation of melatonin. Chemical structure of the fluoroacyl derivative obtained during the derivatization

of melatonin using PFPA (pentafluoropropionic anhydride), according the gas chromatography-mass spectrometry (GC-MS) analysis. Acetyl CoA, … Considering our previous observations, we assumed that Inhibitors,research,lifescience,medical melatonin undergoes enzymatic acetylation during the night, under the control of NAT, and that this leads to an N-acetyl-β-carboline, which we call carbo2. We conclude that melatonin Inhibitors,research,lifescience,medical is a bioprecursor of hypnotic acetyl metabolites, such as carbo2. We have validated this assumption in several ways. Acetylation of melatonin in chick pineal Selleckchem Kinase Inhibitor Library glands Chick pineal glands were observed during an alternate light-dark program at 37°C for 7 Inhibitors,research,lifescience,medical days. In the middle of dark phase, they were treated with pHJacetyl coenzyme A and melatonin (or 2-oxomelatonin) for 30 min. Figure 5 and Figure 6 show that melatonin (or 2-oxomelatonin) undergoes an aeetylation that is significantly higher (P<0.002, in the middle of dark phase; P<0.0005, 1 h before end of dark phase [or P<0.00005 for 2oxomelatonin over the whole dark phase]) than that observed in Inhibitors,research,lifescience,medical controls (nonsignificant when melatonin was replaced by phosphate buffer).

Figure 5. Acetylation capacity of various substrates in chick pineal glands in an alternate light-dark program Isotretinoin (light 6. 00 am to 6. 00 pm; dark 6. 00 pm to 6. 00 am) and collected in the middle of dark phase (midnight). NAS, N-acetylserotonin; 5-MT, 5-methoxytryptamine; … Figure 6. Acetylation capacity of various substrates in chick pineal glands in an alternate light-dark program (light 8. 00 am to 8. 00 pm; dark 8. 00 pm to 8. 00 am) and collected 1 h before the light phase (7. 00 am). 5-MT, 5-methoxytryptamine; MEL, melatonin; … GC-MS indicated the biosynthesis of [3H]carbo2 for five chick pineal glands collected in the middle of dark phase (Table II). Table II. Amount of [3H]carbo2 collected from five chick pineal glands the middle of the dark phase of an alternate light-dark (12 h: 12 h) program.