Quantitative Structure-Activity Relationships (QSARs) for Odor Thresholds of Volatile Organic Compounds (VOCs)

Abstract

A theoretical model for correlating odor thresholds of volatile organic compounds (VOCs) with their simple physicochemical properties has been developed. The partition coefficient between octanol and water, and that between water and air were used to model the partition process of airborne chemicals into the biophase where the olfactory signal is transformed. Validation was performed by fitting data on odor thresholds and partition coefficients for acetates, alcohols, ketones and amines into the model. Quantitative structure‐activity relationships (QSARs) for the four series were developed from the model. The results suggest that acetates, alcohols and ketones probably bind to a common receptor site located in the hydrophobic interior of the lipid bi‐layer membrane of the olfactory cilia. Amines probably bind to a different receptor site located closer to the mucus layer. The results also suggest that odor thresholds of related VOCs which appear to share a common receptor site may be additive.

The Correlation and Prediction of VOC Thresholds for Nasal Pungency, Eye Irritation and Odour in Humans

“…This predicted cut-off effect has a very important consequence. Hau et al [34] have used their partition model [33] to predict odor thresholds for VOCs found in the indoor environment. This partition model does not include any cut-off effect at all, and hence higher homologues will be predicted to be much more potent than on our model.…”

“…Such correlations are of limited practical use, and of no mechanistic value. A more detailed analysis [33,34] led to equation (6), where the ODT values were taken from the AlHA compilation [35].…”

Trigeminal Chemosensation

“…Interestingly, all these descriptors are physicochemical parameters and do not involve the precise chemical structures of the compounds. Attempts have also been made to correlate olfactory potency (Anker and Jurs, 1990;Chastrette, 1997;Dravnieks, 1977;Egolf and Jurs, 1993;Hau and Connelll, 1998;Rossiter, 1996;Schnabel, Belitz, and von Ranson, 1988;Shvets and Dimoglo, 1998). For the most part these relationships are difficult to interpret either chemically or mechanistically (Abraham, 1996).…”

The Correlation and Prediction of VOC Thresholds for Nasal Pungency, Eye Irritation and Odour in Humans

“…Such correlations are of limited practical use, and of no mechanistic value. A more detailed analysis [33,34] led to equation (6), where the ODT values were taken from the AIHA compilation [35]:…”