Phenolic Compounds in Field Horsetail (Equisetum arvense L.) as Natural Antioxidants

Neda Mimica-Dukic,Biljana Bozin,Natasa Simin,Dejan Orcic,Jelena Cvejic,Emilija Jovin

doi:10.3390/molecules13071455

Abstract

In this paper, the study of antioxidant activity and phenolic composition of three different extracts (EtOAc, n-BuOH and H2O) of field horsetail (Equisetum arvense L.) is presented. The antioxidant activity has been evaluated measuring the total reducing power (expressed by Ascorbate Equivalent Antioxidant Capacity - AEAC), inhibition of lipid peroxidation, and free radical scavenging capacity (RSC) towards 2,2-diphenyl-1-picrylhydrazyl (DPPH radical) and nitric oxide (NO), respectively. In addition, the total flavonoid content (TFC) and phenolic constituents of each extract have been determined. The results obtained show that the highest RSC regarding both DPPH and NO radicals is expressed by EtOAc extract (EC50=2.37 μg/mL and EC50=90.07 μg/mL, respectively), and the lowest by H2O extract (EC50=37.2 μg/mL and EC50>333.33 μg/mL, respectively). n-BuOH extract showed the highest total reducing power (AEAC=13.40 μg/mL). Differences in the phenolic composition of examined extracts are found comparing the HPLC chemical profiles. Although, isoquercitrin is the main flavonoid in both EtOAc and n-BuOH extracts, a considerable amount of di-E-caffeoyl-meso-tartaric acid was presented in the n-BuOH extract. In H2O extract high content of phenolic acids and low percentage of flavonoids were detected.

Highlights

This study is a continuation of our efforts to evaluate plant extracts as sources of natural antioxidants [1]
Flavonoid glycosides and di-E-caffeoyl-meso-tartaric acid have been identified by HPLC-DAD analysis of extracts of E
The main compound in the EtOAc extract was quercetin 3-O-glucoside (152 mg rutin/g dry extract (mg/g DE)), while apigenin 5-O-glucoside and kaempferol 3-O-glycoside were detected in considerable amounts (22.4 mg/g and 26.2 mg/g DE, respectively) (Figure 1a, Table 1)

Summary

Introduction

This study is a continuation of our efforts to evaluate plant extracts as sources of natural antioxidants [1]. The dominant compounds in European plants are quercetin 3-O-glucoside, apigenin 5-O-glucoside and dicaffeoyl-meso-tartaric acid [6]. The antioxidant activity of three separated fractions of methanolic extract (EtOAc, n-BuOH and H2O) of Equisetum arvense sterile stems has been investigated in the present study.

Results

Conclusion