LC-ESI-QTOF/MS Characterization of Phenolic Compounds from Medicinal Plants (Hops and Juniper Berries) and Their Antioxidant Activity.

Jiafei Tang,Hafiz A R Suleria,Frank R Dunshea

doi:10.3390/foods9010007

Jiafei Tang, Hafiz A R Suleria + Show 1 more

Open Access

https://doi.org/10.3390/foods9010007

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Abstract

Hops (Humulus lupulus L.) and juniper berries (Juniperus communis L.) are two important medicinal plants widely used in the food, beverage, and pharmaceutical industries due to their strong antioxidant capacity, which is attributed to the presence of polyphenols. The present study is conducted to comprehensively characterize polyphenols from hops and juniper berries using liquid chromatography coupled with electrospray-ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS) to assess their antioxidant capacity. For polyphenol estimation, total phenolic content, flavonoids and tannins were measured, while for antioxidant capacity, three different antioxidant assays including the 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assay, the 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cation decolorization assay and the ferric reducing-antioxidant power (FRAP) assay were used. Hops presented the higher phenolic content (23.11 ± 0.03 mg/g dw) which corresponded to its strong antioxidant activity as compared to the juniper berries. Using LC-ESI-QTOF/MS, a total of 148 phenolic compounds were tentatively identified in juniper and hops, among which phenolic acids (including hydroxybenzoic acids, hydroxycinnamic acids and hydroxyphenylpropanoic acids) and flavonoids (mainly anthocyanins, flavones, flavonols, and isoflavonoids) were the main polyphenols, which may contribute to their antioxidant capacity. Furthermore, the HPLC quantitative analysis showed that both samples had a high concentration of phenolic acids and flavonoids. In the HPLC quantification, the predominant phenolic acids in hops and juniper berries were chlorogenic acid (16.48 ± 0.03 mg/g dw) and protocatechuic acid (11.46 ± 0.03 mg/g dw), respectively. The obtained results highlight the importance of hops and juniper berries as a rich source of functional ingredients in different food, beverage, and pharmaceutical industries.

Highlights

Medicinal plants are used in different food, beverage, and pharmaceutical industries
Hops and juniper berries are rich in phenolic compounds that can contribute to antioxidant capacity and provide a pleasant sensory quality to beverages [4,5,6]
The amount of phenolics content in both samples were determined by the total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC), and the results are expressed as gallic acid equivalents, quercetin equivalent, and catechin equivalent, respectively

Summary

Introduction

Medicinal plants are used in different food, beverage, and pharmaceutical industries. They are rich in bioactive compounds especially polyphenols which can contribute to human health. Most of the modern beers are formulated with hops, which contribute bitterness flavors and act as natural preservatives and stabilizers [4]. Some of the brewers normally add a few other flavoring plants such as juniper berries that contain bitter substances, giving the beer a well-rounded, balanced, and tasty bitterness [5]. Hops and juniper berries are rich in phenolic compounds that can contribute to antioxidant capacity and provide a pleasant sensory quality to beverages [4,5,6]

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