Indole derivatives (I), their enantiomers, diastereomers and their acid/base addition salts are new. Indole derivatives of formula (I), their enantiomers, diastereomers and their acid/base addition salts are new. R 11-6C alkyl, 3-8C cycloalkyl or 3-8C cycloalkyl-1-6C alkyl, preferably alkyl； NR 2R 35-8 membered heterocycle, preferably piperidinyl； and n : 2-6, preferably 2. An independent claim is included for the preparation of (I). [Image] ACTIVITY : Hypnotic； Tranquilizer； Antidepressant； Cardiovascular-Gen； Gastrointestinal-Gen； Neuroleptic； Anorectic； Anticonvulsant； Antidiabetic； Antiparkinsonian； Nootropic； Antimigraine； Neuroprotective； Endocrine-Gen； Contraceptive； Immunomodulator； Cytostatic. MECHANISM OF ACTION : Melatonin receptor binder. The affinity of (I) to bind with melatonin receptors MT1 and MT2 was tested using 2-[ 1>； 2>； 5>；I]-iodomelatonin as reference radioligand. The results showed that (I) exhibited an inhibition constant value of less than 1 mu M.
