Metabolomics for the Authentication of Natural Extracts Used in Flavors and Fragrances: the Case Study of Violet Leaf Absolutes from Viola odorata

Abstract

Natural extracts used in fine fragrances (alcoholic perfumes) are rare and precious. As such, they represent an interesting target for fraudulent practices called adulterations. Absolutes, important materials used in the creation of perfumes, are obtained by organic solvent extraction of raw plant materials. Because the nonvolatile part of these natural extracts is not normalized and scarcely reported, highlighting potential adulterations present in this fraction appears highly challenging. For the first time, we investigated the use of nontargeted UHPLC-ToFMS metabolomics for this purpose, considering Viola odorata l., a plant largely used in the perfume industry, as a model. Significant differences in the metabolic fingerprints of the violet leaf absolutes were evidenced according to geographical locations, and/or adulterations. Additionally, markers of the geographical origin were detected through their molecular weight/most probable molecular formula and retention time, while adulterations were statistically validated. In this study, we thus clearly demonstrated the efficiency of UHPLC-ToFMS-based metabolomics in accelerating both the identification of the origin of raw materials as well as the search for potential adulterations in absolutes, natural products of high added value.

Pharmacy and Fragrances: Traditional and Current Use of Plants and Their Extracts

“…The concept of terpenoid refers to a very numerous set of molecules of plant origin whose precursor is isopentenyl diphosphate and are assembled and modified in many different ways, always based on the isopentane skeleton. Most terpenoids have multicyclic structures, which differ from each other not only in functional groups but also in their basic carbon skeleton [77]. These functional groups of volatile terpenoids (alcohols, ketones, aldehydes, esters) are responsible for the different odors of extracts to elaborate fragrances.…”

“…In recent years, both official institutions and the industry have become aware of the problem of fragrance allergy, and there have been important changes in legislation. Until a few years ago, manufacturers were not obliged to specify the chemical compounds considered as fragrances contained in the product, and now they are committed to declaring them in some cases under a confidentiality contract since their composition is subject to analysis by chromatography, spectroscopy, mass spectrometry and electronic nose methods [77,78]. Previously, people allergic to fragrances had to avoid any hygiene and house- Table 1 does not indicate the concentrations of these molecules; since the percentages of essence vary within the same species, there are varieties that require optimal conditions of climate, soil, adequate cultivation and collection at the time of the year in which the essential oils are of the highest quality.…”