[P32] Study of Odorants Sharing the Odor Notes of an Aroma Blending Mixture by a Pharmacophore Approach

Odors perceived in our environment are mainly the result of mixtures of odorants whose the specific mechanisms involved in their processing remain poorly understood [1]. In previous studies performed at INRAE-CSGA [2], the perception of a mixture of ethyl isobutyrate (Et-iB, strawberry-like odor, STR) and ethyl maltol (Et-M, caramel-like odor, CAR) was investigated in comparison with a reference (allyl hexanoate, Al-H, pineapple-like odor, PNA) chosen to evoke an odor close to the one expected in the mixture. The binary specific mixture of Et-iB and Et-M was judged as more typical of a pineapple odor than the individual components. Some studies highlight the significance of the biological function of odorant, that is to say their odor, to understand odorant discrimination [3, 4]. From this perspective, we selected molecules having two of the three odors STR, CAR or PNA from the large odorants database that we recently used to perform a multivariate statistical analysis [5]. The pharmacophore generation were performed separately using 9 molecules STR-CAR on the one hand, and 4 molecules STR-PNA on the second hand. We used Common Feature Pharmacophore Generation protocol (Discovery Studio 4.5, Biovia) to generate pharmacophore hypotheses [6]; the maximum number of generated hypotheses for each run was set to 10. In our study, the pharmacophoric features considered are hydrogen bond acceptors (HBA/HBA-lip) and hydrophobic regions (HY/HY-Al). All the hypotheses generated from both the STR-CAR and the STR-PNA sets are made up of 2 HBA/HBA-lip. Besides, STR-CAR hypotheses have only 1 HY/HY-Al while there are 2 for STRPNA hypotheses. We compared the best significant hypotheses generated from STR-CAR and STRPNA. A distance close to 8 Å between the centers of at least one HY and one HBA is common to STR-CAR and STR-PNA models. The pharmacophore comparison of the two models revealed a satisfactory mapping of the features. The obtained result is in line with the scheme of olfactory coding, and is consistent with the hypothesis that molecules sharing the odors involved in a blending mixture could recognize a common set of ORs