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

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.

HPLC-DAD-ESI-QTOF-MS Determination of Bioactive Compounds and Antioxidant Activity Comparison of the Hydroalcoholic and Water Extracts from Two Helichrysum italicum Species

“…Compound 54 was identified as kaempferol glycoside ( m / z = 447). Both have already been reported in H. italicum before [ 22 , 28 , 29 ]. Compound 61 , with a molecular ion at m / z = 489 and a fragment ion [M−H-204] − at m / z = 285 produced after acetylhexoside loss, was therefore identified as kaempferol acetylglycoside, which is reported here for the first time.…”

Comparative Study on the Phytochemical Composition and Antioxidant Activity of Grecian Juniper (Juniperus excelsa M. Bieb) Unripe and Ripe Galbuli

“…The 70% ethanol extract of unripe J. excelsa galbuli from location 3 also showed the highest antioxidant potential by copper reduction assay—473.9 mM TE/g dw. Antioxidant capacity can vary and depends on the sample and the nature and type of solvent extraction [ 56 ]. In general, it was reported that ethanol extract of J. communis showed better scavenging activity in the FRAP assay among five different Juniperus species , including J. communis , J. excelsa , J. foetidissima , J. oxycedrus , and J. sabina [ 53 ].…”

Screening and Characterization of Phenolic Compounds and Their Antioxidant Capacity in Different Fruit Peels

“…For the phenolic estimation in selected fruit peel samples, TPC, TFC, and TTC assays were performed, while for measuring their antioxidant capacities, four different types of antioxidant assays including FRAP, DPPH, ABTS, and TAC were performed by adopting our previously published methods of Tang, et al [ 20 ], explained in the supplementary material . The data was determined using a Multiskan ® Go microplate photometer (Thermo Fisher Scientific, Waltham, MA, USA).…”