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a b s t r a c tAccording to recent studies, the antioxidant and anticancer related properties of European hornbeam (Carpinus betulus L.) leaf extracts are remarkable, making it a possible raw material for medicine, requiring the identification of major active compounds and the assessment of the antioxidant properties of the extracts. In the present work the high-performance liquid chromatographic/multistage mass spectrometric characterization of the antioxidant polyphenolic compounds as well as the evaluation of the seasonal changes in the major antioxidant capacity and related parameters (DPPH, ABTS, FRAP, total phenol content, total flavonoid content and total flavan-3-ol content) have been carried out for the leaves of European hornbeam for the first time. The extracts exhibited the highest antioxidant capacity in August, basing on the FRAP (106.24 ± 3.10 mg AAE/g dw.) and DPPH (IC 50 : 4.63 ± 0.88 g/ml) assays and in May, based on the ABTS (329.78 ± 23.89 mg TE/g dw.) method. From the August extract a total of 171 compounds, including phenolic acids, flavonoid glycosides, tannins, catechins and procyanidins have been characterized and identified. According to the HPLC-PDA peak areas, the most abundant polyphenolic compounds in the August extracts were chlorogenic acid, ellagic acid, ellagitannins, myricetin-, luteolin-, quercetin-and apigenin glycosides. Further research is needed for the elucidation of the compounds which are primarily responsible for the antioxidant properties.

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Wood logging generates considerable amounts of waste biomass (e.g. cones, bark, leaves, and roots), worthwile to use, as a potential source of antioxidants. Polyphenols represent an important type of non-enzymatic antioxidants in plants. Current data in scientific literature regarding the antioxidant content of coniferous cones and the antioxidant concentrations at different ripening stages is limited and have not been investigated in detail yet. Our investigation aimed to implement an ultrasonic extraction method for the assessment and comparison of the antioxidant polyphenol content of conifer cones: six arbitrarily selected taxa (Cedrus atlantica, Larix decidua, Picea abies, Pinus nigra, Pseudotsuga menziesii, Tsuga canadensis) commonly found in Hungary were investigated in the present study, which provides methodology for future investigations. The comparison of green, mature, and opened cones were carried out for each taxon. Folin-Ciocâlteu total phenol content, ferric reducing ability of plasma (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays were used to assess the antioxidant properties. The 30 min ultrasonic extraction using acetone:water 80:20 v/v solution resulted in the optimum yield on total polyphenols, FRAP, and DPPH. Best values were found for green cones, followed by mature, and opened cones for each species. Overall antioxidant power was determined by a scoring system that combined the three assay results. Taxa with the highest scores were Picea abies and Tsuga Canadensis, which contained high amounts of antioxidants in both green and mature cones and, surprisingly, also in opened cones (P. abies). Results provide a basis for future investigation and comparison involving a large number of taxa.

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