Untargeted and Targeted Metabolomic Profiling of Australian Indigenous Fruits

Abstract

Selected Australian native fruits such as Davidson's plum, finger lime and native pepperberry have been reported to demonstrate potent antioxidant activity. However, comprehensive metabolite profiling of these fruits is limited, therefore the compounds responsible are unknown, and further, the compounds of nutritional value in these native fruits are yet to be described. In this study, untargeted and targeted metabolomics were conducted using the three fruits, together with assays to determine their antioxidant activities. The results demonstrate that targeted free and hydrolysed protein amino acids exhibited high amounts of essential amino acids. Similarly, important minerals like potassium were detected in the fruit samples. In antioxidant activity, Davidson's plum reported the highest activity in ferric reducing power (FRAP), finger lime in antioxidant capacity (ABTS), and native pepperberry in free radical scavenging (DPPH) and phosphomolybdenum assay. The compounds responsible for the antioxidant activity were tentatively identified using untargeted GC×GC-TOFMS and UHPLC-QqQ-TOF-MS/MS metabolomics. A clear discrimination into three clusters of fruits was observed using principal component analysis (PCA) and partial least squares (PLS) analysis. The correlation study identified a number of compounds that provide the antioxidant activities. GC×GC-TOFMS detected potent aroma compounds of limonene, furfural, and 1-R-α-pinene. Based on the untargeted and targeted metabolomics, and antioxidant assays, the nutritional potential of these Australian bush fruits is considerable and supports these indigenous fruits in the nutraceutical industry as well as functional ingredients for the food industry, with such outcomes benefiting Indigenous Australian communities.

Untargeted Metabolomics Analysis Using FTIR and UHPLC-Q-Orbitrap HRMS of Two Curculigo Species and Evaluation of Their Antioxidant and α-Glucosidase Inhibitory Activities

“…The metabolites in complex biological samples of Curculigo species could be identified rapidly and accurately using a metabolomics analysis to figure out their bioactive compounds. In the metabolomics analysis, there are two approaches to identifying the metabolites: the targeted and non-targeted analysis [ 9 , 10 ]. In the non-targeted analysis, metabolite fingerprinting and profiling could provide the complete identification of metabolites from a biological sample of Curculigo species.…”

“…The analytical instrumentations used to study the metabolites of Curculigo species were Fourier-transform infrared (FTIR) spectrophotometer and UHPLC-Q-Orbitrap HRMS to obtain qualitative and quantitative data. Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) platforms have been widely used in plant science for metabolomics applications to identify and quantify compounds [ 10 ], and this approach is more sensitive and accurate for detecting metabolites [ 11 ].…”

Chemical Fingerprinting and Biological Evaluation of the Endemic Chilean Fruit Greigia sphacelata (Ruiz and Pav.) Regel (Bromeliaceae) by UHPLC-PDA-Orbitrap-Mass Spectrometry

“…This is a dual high resolution with accurate mass (HRAM) spectrometer with an orbital trap (Orbitrap), a quadrupole (Q), and a high-performance collision cell (HCD), capable of producing high-resolution parent ions and diagnostic MS daughter fragments. The hyphenated ultrahigh performance liquid chromatography-photodiode array detection coupled with a Orbitrap mass spectrometry (UHPLC-PDA-Orbitrap-MS) approach is a key tool for the identification of secondary metabolites in plants and edible fruits [15][16][17].…”

Special Issue on “Fruit Metabolism and Metabolomics”

“…This Special Issue covers a range of fruit species, including model fruit (tomato [12][13][14]), temperate (kiwifruit [15], mulberry [16]) or tropical fruit crops (pineapple [17], cashew [18]), genetic resources (melon [19]), and indigenous fruit (Davidson's plum, finger lime and native pepper berry [20]). Different analytical approaches are covered also: near-infrared spectroscopy (NIRS) [18], gas chromatography coupled to mass spectrometry (GC-MS) [17], liquid chromatography coupled to mass spectrometry (LC-MS) [16,18,21,22], LC-MS/MS [20], and a combination of several analytical strategies including nuclear magnetic resonance spectroscopy (NMR), GC-MS and LC-MS [19] or several omics [15]. The original research articles can be classified according to scientific domains: biochemical phenotyping of genetic resources for collection maintenance or intraspecific classification, generating knowledge about fruit growth, ripening and post-harvest, understanding metabolism, characterizing defence priming, identifying bioactive compounds for human nutrition and health.…”

“…In relation to human health, in white and black mulberry fruits, combining an LC-MS method with assays for (i) α-glucosidase inhibitory activity and (ii) antioxidant activity [16], allowed for identifying a list of key bioactive compounds with antioxidant and/or α-glucosidase inhibitory activities. Similarly, based on targeted and untargeted metabolite profiling and antioxidant assays on selected Australian native fruits, a number of compounds that provide the antioxidant activities were identified [20].…”