Abstract
This study is a comparative investigation of antioxidant and antibacterial properties of tree bark extracts of three common European species, Prunus avium L., Larix decidua Mill. and Castanea sativa Mill. The bioactive compounds present in the bark were recovered in 80% aqueous ethanol using ultrasound as the green extraction method. The antioxidant potential of the extracts was assessed with multiple biochemical assays: total phenol content (TPC) expressed in gallic acid equivalent (GAE), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) expressed in trolox equivalent (TE), and ferric reducing ability of plasma (FRAP) expressed in ascorbic acid equivalent (AAE). Sweet chestnut bark extract showed the highest antioxidant activity with TPC of 174.25 ± 16.95 mg GAE/g dry weight, DPPH (IC50) of 2.69 ± 0.03 μg/mL, ABTS of 739.65 ± 24.41 mg TE/g dry weight and FRAP of 207.49 ± 3.62 mg AAE/g dry weight. The antibacterial activity of the extracts was evaluated by disk diffusion test, minimal inhibitory concentration (MIC) assay and bacterial growth curves. Sweet chestnut bark extract gave IC50 values of 0.25 mg/mL and 1.00 mg/mL against E. coli and S. aureus, respectively. The polyphenolic profiling of the bark extracts was performed to identify the major compounds responsible for the bioactivities using high-performance liquid chromatography/tandem mass spectrometry (HPLC–MS/MS). The bark extracts were rich in natural antioxidants, thus holding tremendous potential for use as natural additives in food industry.Graphic abstract
Highlights
In Europe, forests cover 215 million ha, i.e., one-third of the land area, and the forest-sector constitutes about 0.8% of its GDP giving a livelihood to over 3 million people [1]
The highest total phenol content (TPC) was obtained for the chestnut bark (174.25 ± 16.95 mg gallic acid equivalent (GAE)/g dw), while the lowest TPC was obtained for the cherry bark (112.88 ± 17.27 mg GAE/g dw)
One of the earlier studies evaluated the phenolic content of the bark extracts after separating the outer bark from the inner bark [10]; for practical reasons and from a commercialization point of view, we chose to study the whole bark of the tree trunks
Summary
In Europe, forests cover 215 million ha, i.e., one-third of the land area, and the forest-sector constitutes about 0.8% of its GDP giving a livelihood to over 3 million people [1]. The polyphenols in plants are involved in their internal defense, regulation of growth, hormonal activity, pH and metabolism [4]. They exhibit numerous physiological properties such as antioxidant, antimicrobial, antiinflammatory, anti-carcinogenic, and have tremendous potential to be used in making dietary supplements, functional food additives, pharmaceutical products and cosmetics [5]. The choice of extraction method and solvent depends on the plant matrix properties, physicochemical properties of analyte, analyte-solvent compatibility, process efficiency in terms of yield and purity, environmental impact, as well as the overall cost [3]. The principle of ultrasonic extraction is based on cavitation, i.e., the formation, growth and violent collapse of bubbles in the solvent medium giving rise to local hotspots. The resulting physical effects cause the fragmentation and erosion of the plant cells, increased solvent penetration (sonocapillary effect) and subsequent washing out of the cell contents (sonoporation) [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
