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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

Paper ID Volume ID Publish Year Pages File Format Full-Text
30151 44460 2015 10 PDF Available
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
Abstract

•Arbutus unedo plants grew under different UV/precipitation treatments in the field.•Leaf phenolic content and antioxidant activity were mainly affected by season.•Theogallin and quercitrin increased upon leaf exposure to UV-A and UV-B respectively.•UV-A exposure under reduced rainfall decreased leaf quercetins and one kaempferol.•Leaf antioxidant activity increased by UV-A and UV-B under low watering.

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 [DPPH● 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.

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Keywords
Antioxidant activity; Arbutus unedo; Drought; Phenolic compounds; UV-A radiation; UV-B radiation
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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
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 153, December 2015, Pages 435–444
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us