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Interactive effects of UV radiation and reduced precipitation on the seasonal leaf phenolic content/composition and the antioxidant activity of naturally growing Arbutus unedo plants

The effects of UV radiation and rainfall reduction on the seasonal leaf phenolic content/composition and antioxidant activity of the Mediterranean shrub Arbutus unedo were studied. Naturally growing plants of A. unedo were submitted to 97% UV-B reduction (UVA), 95% UV-A + UV-B reduction (UV0) or near-ambient UV levels (UVBA) under two precipitation regimes (natural rainfall or 10-30% rainfall reduction). Total phenol, flavonol and flavanol contents, levels of eight phenols and antioxidant activity [DPPHâ-? radical scavenging and Cu (II) reducing capacity] were measured in sun-exposed leaves at the end of four consecutive seasons. Results showed a significant seasonal variation in the leaf content of phenols of A. unedo, with the lowest values found in spring and the highest in autumn and/or winter. Leaf ontogenetic development and/or a possible effect of low temperatures in autumn/winter may account for such findings. Regardless of the watering regime and the sampling date, plant exposure to UV-B radiation decreased the total flavanol content of leaves, while it increased the leaf content in quercitrin (the most abundant quercetin derivative identified). By contrast, UV-A radiation increased the leaf content of theogallin, a gallic acid derivative. Other phenolic compounds (two quercetin derivatives, one of them being avicularin, and one kaempferol derivative, juglanin), as well as the antioxidant activity of the leaves, showed different responses to UV radiation depending on the precipitation regime. Surprisingly, reduced rainfall significantly decreased the total amount of quantified quercetin derivatives as well as the DPPH scavenging activity in A. unedo leaves. To conclude, present findings indicate that leaves of A. unedo can be a good source of antioxidants throughout the year, but especially in autumn and winter

This research was supported by the Spanish Government (CGL2010-22283 and CGL2010-18546)

Elsevier

Manager: Ministerio de Ciencia e Innovación (Espanya)
Author: Nenadis, Nikolaos
Llorens i Guasch, Laura
Koufogianni, Agathi
Díaz, Laura
Font Garcia, Joan
González Gutiérrez, Josep Abel
Verdaguer Murlà, Dolors
Abstract: The effects of UV radiation and rainfall reduction on the seasonal leaf phenolic content/composition and antioxidant activity of the Mediterranean shrub Arbutus unedo were studied. Naturally growing plants of A. unedo were submitted to 97% UV-B reduction (UVA), 95% UV-A + UV-B reduction (UV0) or near-ambient UV levels (UVBA) under two precipitation regimes (natural rainfall or 10-30% rainfall reduction). Total phenol, flavonol and flavanol contents, levels of eight phenols and antioxidant activity [DPPHâ-? radical scavenging and Cu (II) reducing capacity] were measured in sun-exposed leaves at the end of four consecutive seasons. Results showed a significant seasonal variation in the leaf content of phenols of A. unedo, with the lowest values found in spring and the highest in autumn and/or winter. Leaf ontogenetic development and/or a possible effect of low temperatures in autumn/winter may account for such findings. Regardless of the watering regime and the sampling date, plant exposure to UV-B radiation decreased the total flavanol content of leaves, while it increased the leaf content in quercitrin (the most abundant quercetin derivative identified). By contrast, UV-A radiation increased the leaf content of theogallin, a gallic acid derivative. Other phenolic compounds (two quercetin derivatives, one of them being avicularin, and one kaempferol derivative, juglanin), as well as the antioxidant activity of the leaves, showed different responses to UV radiation depending on the precipitation regime. Surprisingly, reduced rainfall significantly decreased the total amount of quantified quercetin derivatives as well as the DPPH scavenging activity in A. unedo leaves. To conclude, present findings indicate that leaves of A. unedo can be a good source of antioxidants throughout the year, but especially in autumn and winter
This research was supported by the Spanish Government (CGL2010-22283 and CGL2010-18546)
Format: application/pdf
Document access: http://hdl.handle.net/10256/11968
Language: eng
Publisher: Elsevier
Collection: info:eu-repo/semantics/altIdentifier/doi/10.1016/j.jphotobiol.2015.10.016
info:eu-repo/semantics/altIdentifier/issn/1011-1344
info:eu-repo/grantAgreement/MICINN//CGL2010-18546/ES/LAS NUBES Y SUS EFECTOS SOBRE LA RADIACION: DEL ESTUDIO DE SITUACIONES A ESCALA LOCAL AL ANALISIS CLIMATOLOGICO DE ALCANCE GLOBAL. INTERACCIONES CON EL AEROSOL ATMOSFERICO/
info:eu-repo/grantAgreement/MICINN//CGL2010-22283/ES/CAMBIO GLOBAL Y ECOSISTEMAS MEDITERRANEOS: RESPUESTAS DE LA VEGETACION A LOS CAMBIOS PREVISTOS EN LA RADIACION UVB Y%2FO DEFICIT HIDRICO ANTES Y DESPUES DE UNA PERTURBACION/
Rights: Tots els drets reservats
Subject: Radiació ultraviolada
Ultraviolet radiation
Plantes -- Efecte de la radiació
Plants -- Effect of radiation on
Plantes -- Efecte de la sequera
Plants, Effect of drought on
Title: Interactive effects of UV radiation and reduced precipitation on the seasonal leaf phenolic content/composition and the antioxidant activity of naturally growing Arbutus unedo plants
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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