Non-targeted NMR chemical profiling of vegetable oils: a two-path workflow for fast access to a detailed metabolome

Vegetable oils are increasingly used to formulate bioactive ingredients with pharmaceutical, nutraceutical or cosmeceutical applications. Their biological properties depend directly on their chemical profile, but so far it remains difficult to simultaneously characterise the major long chain lipidic constituents together with the minor but valuable unsaponifiable constituents specific to botanical species. Therefore accurate and comprehensive analytical strategies appear crucial. In this work, a NMR-based dereplication workflow was developed to decipher the metabolome of vegetable oils. The approach involves either a direct liquid-liquid extraction of minor oil constituents or a saponification treatment on the crude starting oil, followed by liquid-liquid fractionation, and direct NMR analysis of all fractions. Oil metabolites are then identified with the help of computer tools and a natural metabolite database. The whole process was applied to a grape seed oil sample, resulting in a rapid and unambiguous identification of 23 metabolites including fatty acid derivatives, triterpenes, sterols, and tocopherols. This NMR-based analytical workflow offers interesting perspectives for the chemical profiling of vegetable oils and oily extracts.