Liquid Chromatographic Quadrupole Time-of-Flight Mass Spectrometric Untargeted Profiling of (Poly)phenolic Compounds in Rubus idaeus L. and Rubus occidentalis L. Fruits and Their Comparative Evaluation.

Lapo Renai,Edgardo Giordani,Massimo Del Bubba,Ugo Chiuminatto,Francesca Tozzi,Marynka Ulaszewska,William Antonio Petrucci,Stefania Nin,Cristina Vanessa Agata Scordo

doi:10.3390/antiox10050704

Abstract

This study provided a detailed profiling of the antioxidant and bioactive compounds occurring in three varieties of Rubus idaeus L. fruits (“Fall Gold”, “Glen Ample” and “Tulameen”) compared to Rubus occidentalis L. black raspberry (“Jewel” cultivar), adopting a comprehensive untargeted metabolomics approach developed with UHPLC analysis coupled with quadrupole/time-of-flight high resolution mass spectrometry, using the SWATH® acquisition protocol. The feature selection and annotation workflow, applied to the analysis of raspberry extracts in both polarities, allowed identifying 68 bioactive compounds mainly belonging to the classes of (poly)phenolic compounds. Interestingly, some of these identifications (e.g., ferulic acid glycosides and the ellagitannin-like nobotanin/malabathrin) represent the first report in raspberry fruits. Principal component analysis made possible highlighting the features more related to the expression of a genotype effect within the R. idaeus species or between the two raspberry species herein investigated. Overall, flavanols were the most discriminating features for the Fall Gold variety, whereas ellagitannins and flavonol glycosides represent more distinctive metabolic traits in Glen Ample and Tulameen fruits. Moreover, R. occidentalis Jewel variety was strongly characterized by the occurrence of anthocyanins, such as cyanidin, pelargonidin and delphinidin glycosides.

Highlights

Myricetin derivatives have been identified as typical metabolomics traits of several berries [45], but this study revealed for the first time their occurrence in R. idaeus yellow variety
This paper offers novel information on thephenolic composition of raspberry fruits, thanks to the adopted comprehensive untargeted strategy and data processing for features annotation, together with identity confirmation with authentic standards
Even though most of the identified features belong to the already known major categories ofphenols occurring in raspberry fruits, this study extends the current knowledge of native composition on R. idaeus and above all R. occidentalis, the latter being scarcely investigated elsewhere

Summary

Introduction

Wild berries are well-known sources of bioactive compounds, mainly phenolics, synthesized by the plant secondary metabolism [1,2,3]. Such native chemicals play a crucial role in the prevention of a wide range of chronic and degenerative diseases [4,5]. Within the wide variety of wild berries, raspberry and blackberry are the most consumed edible fruits of a multitude of plant species in the genus Rubus of the Rosaceae family [11]. Rubus fruits are considered important functional foods due to their remarkable nutritional value and content of dietary antioxidants [11,12]. Within Rubus species, blackberry is commonly harvested as spontaneous wild berry, while raspberry is widely cultivated in Europe and North America as Rubus idaeus L. and Rubus occidentalis L. species, respectively [13], with a worldwide annual production of about one million tons in 2019 [14]

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