Structure-minty odour relationships: suggestion of an interaction pattern

Structure–odour relationships for the minty note were studied using a set of 150 compounds (68 minty and 82 not minty) with known olfactory descriptions and chemical structures. The study was based on the HBD (hydrogen bonding and dispersion) theory which considers that interactions involving molecules and receptor sites are mainly hydrogen bonds and dispersion forces. All the compounds of the set were examined and a combination of direct comparisons and chi-square tests allowed identification of relevant structural elements for the minty note. Twenty-four compounds (8 menthol isomers, 4 menthone isomers and 12 carveol and carvone derivatives) were chosen for their very precise olfactory description and because they constitute 12 enantiomeric pairs. Their low-energy conformations were computed using the Sybyl force field. Superimpositions on reference compounds of the likely conformations of each enantiomer were made using the Sybyl package, taking into account relevant structural elements previously identified. These comparisons showed that substituents in minty compounds must meet precise geometrical requirements and that, in spite of differences of location and nature for the functional oxygen group, they can receive a hydrogen bond from the same hypothetical atom of the receptor sites. Finally, from these structural and geometrical characteristics, an interaction pattern was proposed for the minty odour.