Multi-Targeted Metabolic Profiling of Carotenoids, Phenolic Compounds and Primary Metabolites in Goji (Lycium spp.) Berry and Tomato (Solanum lycopersicum) Reveals Inter and Intra Genus Biomarkers.

Doriane Dumont,Annie Chastellier,Laurence Hibrand Saint Oyant,Anne-Laure Fanciullino,Giorgia Danielato,Raphaël Lugan

doi:10.3390/metabo10100422

Abstract

Metabolic profile is a key component of fruit quality, which is a challenge to study due to great compound diversity, especially in species with high nutritional value. This study presents optimized analytical methods for metabolic profiling in the fruits of three Solanaceae species: Lycium barbarum, Lycium chinense and Solanum lycopersicum. It includes the most important chemical classes involved in nutrition and taste, i.e., carotenoids, phenolic compounds and primary compounds. Emphasis has been placed on the systematic achievement of good extraction yields, sample stability, and high response linearity using common LC-ESI-TQ-MS and GC-EI-MS apparatuses. A set of 13 carotenoids, 46 phenolic compounds and 67 primary compounds were profiled in fruit samples. Chemometrics revealed metabolic markers discriminating Lycium and Solanum fruits but also Lycium barbarum and Lycium chinense fruits and the effect of the crop environment. Typical tomato markers were found to be lycopene, carotene, glutamate and GABA, while lycibarbarphenylpropanoids and zeaxanthin esters characterized goji (Lycium spp.) fruits. Among the compounds discriminating the Lycium species, reported here for the first time to our knowledge, chlorogenic acids, asparagine and quinic acid were more abundant in Lycium chinense, whereas Lycium barbarum accumulated more lycibarbarphenylpropanoids A-B, coumaric acid, fructose and glucose.

Highlights

Fruits and vegetables are important components of the human diet
In addition we determined that a fresh sample to solvent volume ratio greater than 150 mg/mL resulted in solvent saturation; the final ratio selected for this study was 80 mg/mL, in agreement with Hempel et al [20]
Gupta et al [22] indicated that a minimum amount of methyl tert-butyl ether (MTBE) is required, and we found that a mixture of EtOH:MTBE (2:1 v/v) was associated with a high increase in the signal of zeaxanthin dipalmitate, the most apolar carotenoid found in our sample (Figure 1b); it provided satisfying compound stability (Figure 1c)

Summary

Introduction

Fruits and vegetables are important components of the human diet. Their consumption is associated with beneficial health effects, partly due to their high contents of phytomicronutrients such as carotenoids and phenolic compounds [1]. Goji berry, labeled a “superfood” because of its high content in phytomicronutrients, belongs to the Lycium genus [2] in the Solanaceae family, like tomato, which is one of the most important food commodity in the world. Tomato is an important model species for the biology of fleshy fruits and nutritional studies, and its genetic proximity with. The complex composition of goji and tomato fruits has been the subject of several studies, using various metabolomics approaches to Metabolites 2020, 10, 422; doi:10.3390/metabo10100422 www.mdpi.com/journal/metabolites.

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