Conformational analysis of melatonin at Hartree–Fock ab initio level

Melatonin is a hormone, which is synthesized and secreted by the pineal gland during darkness and has been implicated in the regulation of several neural and endocrine processes. Conformational analysis of melatonin was performed at Hartree–Fock ab initio level. With the help of STO-3G and 6-31G* basis sets, 192 and 128 conformers were obtained, respectively. In both cases, there were eight conformers with nearly planar 3-amido-side chain and the most stable conformation found had folded structure in accord with previously published results. The present paper compares the Hartree–Fock conformational space of melatonin with the results of active conformation models and conformational analyses published in the literature.