Determination of the Metabolite Content of Brassica juncea Cultivars Using Comprehensive Two-Dimensional Liquid Chromatography Coupled with a Photodiode Array and Mass Spectrometry Detection

Abstract

Plant-based foods are characterized by significant amounts of bioactive molecules with desirable health benefits beyond basic nutrition. The Brassicaceae (Cruciferae) family consists of 350 genera; among them, <i>Brassica</i> is the most important one, which includes some crops and species of great worldwide economic importance. In this work, the metabolite content of three different cultivars of <i>Brassica juncea</i>, namely ISCI Top, "Broad-leaf," and ISCI 99, was determined using comprehensive two-dimensional liquid chromatography coupled with a photodiode array and mass spectrometry detection. The analyses were carried out under reversed-phase conditions in both dimensions, using a combination of a 250-mm microbore cyano column and a 50-mm RP-Amide column in the first and second dimension (²D), respectively. A multi (three-step) segmented-in-fraction gradient for the ²D separation was advantageously investigated here for the first time, leading to the identification of 37 metabolites. In terms of resolving power, orthogonality values ranged from 62% to 69%, whereas the corrected peak capacity values were the highest for <i>B. juncea</i> ISCI Top (639), followed by <i>B. juncea</i> "Broad-leaf" (502). Regarding quantification, <i>B. juncea</i> cv. "Broad-leaf" presented the highest flavonoid content (1962.61 mg/kg) followed by <i>B. juncea</i> cv. ISCI Top (1002.03 mg/kg) and <i>B. juncea</i> cv. ISCI 99 (211.37 mg/kg).