Identification of phenolic compounds in Australian grown dragon fruits by LC-ESI-QTOF-MS/MS and determination of their antioxidant potential

Zhicong Chen,Biming Zhong,Colin J Barrow,Frank R Dunshea,Hafiz A.R Suleria

doi:10.1016/j.arabjc.2021.103151

Zhicong Chen, Biming Zhong + Show 3 more

Open Access

https://doi.org/10.1016/j.arabjc.2021.103151

Copy DOI

Abstract

Dragon fruit is a popular tropical fruit that has a high phenolic content which are the main contributors to the antioxidant potential and health benefits of dragon fruit pulp and peel waste. Although some phenolic compounds in dragon fruit have previously been reported, a comprehensive analysis of complete phenolic profile of the Australian varieties has not been conducted. Thus, the aim of this study was to extract, identify and quantify phenolics from dragon fruits grown in Australia. Phenolic compounds were extracted from the peels and pulps of white and red dragon fruit. Phenolic content was determined by total phenolic content (TPC), total flavonoid content (TFC) and total tannin content (TTC), while antioxidant activities were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), 2,2′-Azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and total antioxidant capacity (TAC). The results showed that dragon fruit pulp had a higher total phenolic content and stronger antioxidant capacity than peel, while the peel had a higher content of flavonoids and tannins than the pulp. Liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS) was used for the characterization of phenolic compounds, a total of 80 phenolics including phenolic acids (25), flavonoids (38), lignans (6), stilbene (3) and other polyphenols (8) were characterized in all dragon fruits. High performance liquid chromatography equipped with photodiode array detector (HPLC-PDA) quantified the phenolic compounds in different portion of dragon fruit and showed that dragon peel had higher concentrations of phenolics than pulp. The results highlighted that both dragon fruit peel and pulp are potential sources of phenolic compounds, with peel in particular being a source of antioxidant phenolics with potential as ingredients for the food and pharmaceutical industries.

Highlights

Dragon fruit (Hylocereus spp.) is a widely consumed tropical fruit which is considered healthy partly due to its high content of phenolic compounds (Zain et al, 2019)
The total phenolic content (TPC) values from our study are close to the study conducted by Choo et al (2016), in which they determined the TPC of white and red dragon fruit pulps to be 0.29 ± 0.02 and 0.24 ± 0.01 mg gallic acid equivalents (GAE)/g
The pattern of the TPC results of Nurliyana et al (2010) was contradictory to our research as they found that white and red peel samples had higher phenolic contents than pulp samples. They attributed the higher phenolic content in peels to the abundance of betacyanins, which contributes to TPC value apart from polyphenols (Tenore et al, 2012)

Summary

Introduction

Dragon fruit (Hylocereus spp.) is a widely consumed tropical fruit which is considered healthy partly due to its high content of phenolic compounds (Zain et al, 2019). Dragon fruit pulp is edible and it is usually eaten raw or used for making commercial products such as juices, ice cream, jam and yogurt (Nurul and Asmah, 2014). The dragon fruit peel is non-edible, and mostly goes to waste, despite its high phenolic content (Kim et al, 2011). Emerging applications to utilise dragon fruit peel waste include fruit spreads and food additives, with isolation or concentration of antioxidants for food, pharmaceutical and cosmetics industries warranting further exploration (Ferreres et al, 2017)

Objectives

Methods

Results

Conclusion