STRUCTURE-ODOR RELATIONSHIPS - A HIGHLY PREDICTIVE TRIDIMENSIONAL INTERACTION-MODEL FOR THE BELL-PEPPER NOTE

Structure-odor relationships for the bell-pepper aroma were studied fo r a set of 160 compounds (58 active and 102 inactive), essentially pyr azine, pyridine and thiazole derivatives. This study was based on the HBD (hydrogen bonding and dispersion) theory, which considers that int eractions involving molecules and receptor sites are mainly hydrogen b onds and dispersion forces. A structural pattern for the bell-pepper n ote was first obtained by comparison of molecular models of different compounds. Statistical evaluation showed that these structural element s alone do not make it possible to propose structure-odor relationship s. Low-energy conformations of the molecules were computed by minimiza tion of their steric energy using molecular mechanics software (MMP2). Comparisons of the likely conformations of a reference compound with those of inactive compounds and enantiomeric structures show that subs tituents of the bell-pepper compounds must meet precise geometrical re quirements. Finally, from these structural and geometrical characteris tics, a tridimensional structural pattern and an interaction model wer e proposed. This interaction model accounts for both the quality and i ntensity of the odor of the molecules studied.