Systematic qualitative analysis of terpenes in mastic (Pistacia lentiscus L.) extract and their fragmentations by UHPLC-Q-Orbitrap-HRMS.

Abstract

Mastic is a natural resin produced by Pistacia lentiscus L. (Anacardiaceae). The beneficial properties of this resin are attributed to its triterpenes and volatile compounds. This study was conducted to screen and characterize the terpenes in mastic ethyl acetate extract (M-Ex). An ultrahigh-performance liquid chromatography coupled to quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-HRMS) method was developed for the qualitative analysis of terpenes in M-Ex. We utilized in-house-isolated compounds as reference substance (Rs), including monoterpenes (A) with α-pinane structures, tetracyclic triterpene (B) containing tirucallane skeletons, and pentacyclic triterpene (C) belonging to olean, moronic, amyrone, and lupane types. Based on the mass spectrometric characteristics of the above compounds, and the difference in characteristic diagnostic fragment ions (DFIs) in isomeric compounds, the terpene compounds were further identified in M-Ex. Out of a total of 70 compounds, including monoterpenes and tetra-, and pentacyclic triterpenes, 20 were accurately determined by Rs, retention time (RT), and DFIs. Based on the cleavage patterns summarized from the above 20 compounds and with reference to the reported literature, another 50 compounds were putatively identified. Based on our discovery, six terpenic acids with A-seco-tirucallane types and one monoterpene dimer were identified for the first time in mastic. Our research serves not only as a foundation for the rapid identification and screening of terpene compounds in mastic but also as a supplementary basis for the identification of such compounds in other types of resins.