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Evaluation of Anti-oxidant Activity and Identification of Major Polyphenolics of the Invasive Weed Oxalis pes-caprae

Authors

  • Ilknur Güçlütürk,

    1. Department of Food Quality and Chemistry of Natural Products, Mediterranean Agronomic Institute of Chania/ Centre International de Hautes Etudes Agronomiques Méditerranéennes, Chania, Crete, Greece
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  • Anastasia Detsi,

    1. Laboratory of Organic Chemistry, Department of Chemical Sciences, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
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  • Erika Krisztina Weiss,

    1. Department of Food Quality and Chemistry of Natural Products, Mediterranean Agronomic Institute of Chania/ Centre International de Hautes Etudes Agronomiques Méditerranéennes, Chania, Crete, Greece
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  • Efstathia Ioannou,

    1. Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens, Athens, Greece
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  • Vassilios Roussis,

    1. Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens, Athens, Greece
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  • Panagiotis Kefalas

    Corresponding author
    • Department of Food Quality and Chemistry of Natural Products, Mediterranean Agronomic Institute of Chania/ Centre International de Hautes Etudes Agronomiques Méditerranéennes, Chania, Crete, Greece
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P. Kefalas, Department of Food Quality and Chemistry of Natural Products, Mediterranean Agronomic Institute of Chania/ Centre International de Hautes Etudes Agronomiques Méditerranéennes, 73100 Chania, Crete, Greece. E-mail: panos@maich.gr

ABSTRACT

Introduction

Phytochemical analyses of weeds, many of which have been used in traditional medicine worldwide, could lead to the identification of secondary metabolites with significant biological activity.

Objective

To perform an assessment of the chemical composition and exploitation potential of the invasive weed Oxalis pes-caprae. To evaluate the anti-oxidant activity of its extracts and isolate and characterise polyphenolic metabolites using LC-DAD-MS (ESI+) and NMR methods.

Methodology

Aerial parts of the invasive weed O. pes-caprae were extracted with solvents of increasing polarity and their major polyphenolic metabolites were identified by LC-DAD-MS (ESI+). The total phenolic content of the extracts was determined using the Folin–Ciocalteu method, while their anti-oxidant activity was evaluated on the basis of their ability to scavenge the stable free radical 1,1-diphenyl-2-picrylhydrazyl and hydrogen peroxide.

Results

The major polyphenolic constituents of the extracts were tentatively characterised as chlorogenic acid, quinic ferulate, luteolin glucoside and cernuoside according to their MS and UV spectroscopic data. Cernuoside, an aureusidin glucoside, was isolated from the methanolic extract of the weed's flowers and its structure was unambiguously identified by 1D- and 2D-NMR spectroscopy. The butanol extract of O. pes-caprae displayed the highest anti-oxidant activity.

Conclusion

The metabolic profile of O. pes-caprae was studied and the structures of the major polyphenolic metabolites based on their MS and UV–vis spectra were tentatively assigned. The aureusidin glucoside cernuoside was isolated and characterised for the first time from O. pes-caprae. The extracts exhibited high levels of anti-oxidant activity. Copyright © 2012 John Wiley & Sons, Ltd.

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