Analyses of Metals Impact on Humulus lupulus Strobili Antioxidant Capacity

Dusan D Paunoic,Aleksandra N Pavlovic,Snezana S Mitic,Gordana M Kocic,Ivana D Rasic Misic,Milan N Mitic

doi:10.37358/rc.20.7.8241

Abstract

This paper presents results of analyses of metal ions effects on hop strobili antioxidant characteristics. Determination of total phenols (TP), total flavonoids (TF) and fifteen phenolic compounds, as well as the antioxidant activity (DPPH, ABTS and FRAP) of hop extracts from eight samples was conducted using UV/Vis spectrophotometry and HPLC method. Contents of 24 elements in mineralized hop samples were determined by ICP-OES. Very strong negative relationship between TP, TF, antioxidant capacity results and Pb, Co, Cr, Sb and Na was determined applying principal component and cluster analyses. Namely, the higher concentrations of these metals were associated with lower contents of TP and TF and lower values of antioxidant tests. Impact of metal ions on phenolic and flavonoids content and antioxidant activity of hop strobili has not been previously published.

Highlights

Hop (Humulus lupulus L) is a plant widely known for its usage in brewing industry, precisely in beer production
3.1.total phenols (TP), total flavonoids (TF) content and antioxidant activity of hop extracts The spectrophotometric results of TP, TF content and antioxidant activity of hop were presented in mg gallic acid equivalents (GAE)/g mg CE/g
The obtained results of DPPH radical scavenging activity ranged from 32.25 μmol Trolox equivalent (TE)/g to 37.5 μmol TE/g, for ABTS from 41.67 μmol TE/g to 46.8 μmol TE/g and for FRAP assay from 30 μmol Fe/g to 75 μmol Fe/g

Summary

Introduction

Hop (Humulus lupulus L) is a plant widely known for its usage in brewing industry, precisely in beer production. All parts of this plant are a source of polyphenolic compounds such as flavonoids, catechins, flavanones, phenolic acids, etc. Large number of studies shows that among all phenolic compounds, flavonoids are of the greatest significance for antioxidant activity of plant. Hydroxyl groups, especially their position, play an important role for antioxidant activity of flavonoids, since they are responsible for donating hydrogen atom and scavenge free radicals [2, 3]. Semiquinones, quinones and reactive oxygen species (ROS) are produced

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