Uncovering heterogeneity of anacardic acids from pistachio shells: A novel approach for structural characterization.

[Display omitted] • Anacardic acids (AnAs) of dried pistachio shells were extracted and investigated. • A green extraction procedure from agrifood waste was applied. • Epoxidation and tandem MS analysis were used to distinguish positional isomers of AnAs. • Epoxidated and native AnAs were separated using a C30 column. • The procedure is informative, simple, and effective and can be extended to other samples. Anacardic acids (AnAs) are important secondary metabolites that occur primarily in plants of the Anacardiaceae family, such as pistachio (Pistacia vera L.). Some AnAs have been associated with health benefits, and the position of the C C double bonds is a crucial feature of these metabolites. Herein, we propose a new strategy based on RPLC separation and detection by ESI-MS/MS, preceded by an epoxidation reaction. The procedure was applied to the green extracts of lignified pistachio shells, and a mixture of AnAs bearing alkyl chains 13:0, 15:0, and 17:1 emerged as prevailing. As positional isomers of AnA 15:1 (Δ8 and Δ6) and AnAs 17:1 (Δ10 and Δ8) were identified for the first time, their discovery paves the way to the systematic study of their potential health-beneficial effects. The developed method was validated and applied to quantify AnAs in pistachio ethanolic extract, showing contents higher than 10 mg/ 100 g of biomass. [ABSTRACT FROM AUTHOR]