Characterization of Phenolic Composition in Lamiaceae Spices by LC-ESI-MS/MS

TLDR

LC‑ESI‑MS/MS was used to identify 38 phenolic compounds in rosemary, oregano, sage, basil, and thyme by comparing retention times and spectra with authentic standards, and when standards were lacking, by accurate mass and MS/MS fragmentation. The 38 compounds fell into hydroxycinnamic acids, hydroxybenzoic acids, flavonoids (17 compounds), and phenolic terpenes, with accurate mass and CID data confirming their elemental compositions and structural features.

Abstract

A total of 38 phenolic compounds in the solid/liquid extracts of five Lamiaceae spices, rosemary, oregano, sage, basil, and thyme, were identified in the present study using LC-ESI-MS/MS. These compounds were distributed in four major categories, namely, hydroxycinnamic acid derivatives, hydroxybenzoic acid derivatives, flavonoids, and phenolic terpenes. Among them, the category of flavonoids was the largest, with 17 compounds. Identification of the phenolic compounds was carried out by comparing retention times and mass spectra with those of authentic standards. If standards were unavailable, phenolic compounds were identified on the basis of accurate mass of pseudomolecular [M − H]− ions and tandem mass spectrometry (MS/MS) data. The results of accurate mass measurements fit well with the elemental composition of the compounds. The diagnostic fragmentation patterns of the compounds during collision-induced dissociation (CID) elucidated the structural information of the compounds analyzed.