Phenolic Composition and Antioxidant Properties of Poplar Bud (Populus nigra) Extract: Individual Antioxidant Contribution of Phenolics and Transcriptional Effect on Skin Aging

The Populus species possess great potential for therapeutical applications, especially for their known anti-inflammatory properties. The antioxidant properties of propolis, a hive product collected by honey bees mainly from poplar bud exudates, suggest that poplar buds also possess antioxidant properties. Here is reported the characterization of the antioxidant properties of an aqueous poplar bud (Populus nigra) extract. It presented a high total phenolic content, and moderate antioxidant properties as determined by ORAC assay. The main phenolic compounds identified were phenolic acids and flavonoid aglycons. These phenolic compounds were analyzed by ORAC assay for their individual antioxidant activity, in order to determine the major contributors to the total antioxidant activity of the extract. Thanks to their high antioxidant activity, caffeic and p-coumaric acids were identified as the major antioxidant components. Representing only 3.5% of its dry weight, these compounds represented together about 50...