Effect of Hybrid Type and Harvesting Season on Phytochemistry and Antibacterial Activity of Extracted Metabolites from Salix Bark

Hundreds of different fast-growing Salix hybrids have been developed mainly for energy crops. In this paper, we studied water extracts from the bark of 15 willow hybrids and species as potential antimicrobial additives. Treatment of ground bark in water under mild conditions extracted 12-25% of the dry material. Preparative high-performance liquid chromatography is proven here as a fast and highly efficient tool in the small-scale recovery of raffinose from Salix bark crude extracts for structural elucidation. Less than half of the dissolved material was assigned by chromatographic (gas chromatography and liquid chromatography) and spectroscopic (mass spectrometry and nuclear magnetic resonance spectroscopy) techniques for low-molecular-weight compounds, including mono- and oligosaccharides (sucrose, raffinose, and stachyose) and aromatic phytochemicals (triandrin, catechin, salicin, and picein). The composition of the extracts varied greatly depending on the hybrid or species and the harvesting season. This information generated new scientific knowledge on the variation in the content and composition of the extracts between Salix hybrids and harvesting season depending on the desired molecule. The extracts showed high antibacterial activity on Staphylococcus aureus with a minimal inhibitory concentration (MIC) of 0.6-0.8 mg/mL; however, no inhibition was observed against Escherichia coli, Enterococcus faecalis, and Salmonella typhimurium. MIC of triandrin (i.e., 1.25 mg/mL) is reported for the first time. Although antibacterial triandrin and (+)-catechin were present in extracts, clear correlation between the antibacterial effect and the chemical composition was not established, which indicates that antibacterial activity of the extracts mainly originates from some not yet elucidated substances. Aquatic toxicity and mutagenicity assessments showed the safe usage of Salix water extracts as possible antibacterial additives.

Description

Funding Information: This work was a part of the Academy of Finland’s Flagship Programme under projects no. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES) and BioColour project supported by the Strategic Research Council at the Academy of Finland (funding nos. 327178, 327213, and 327195). Funding Information: The authors would like to thank Markku Suutari (Carbons Finland Oy), Bo Gertsson (Plant Breeding of Lantmännen Lantbruk), and Matti Virkkunen (VTT Technical Research Center of Finland Ltd.) for supplying the Salix hybrids. They also thank the DDCB core facility at the Faculty of Pharmacy, supported by the University of Helsinki and Biocenter Finland, for providing access to screening instrumentation. Appreciation is also extended to Chunlin Xu and Annika Smeds from Åbo Akademi University for their skillful assistance and discussion. GAU and NOF thank funds provided by FAPESP project 2020/04628-8 and CAPES Financial Code 001. Publisher Copyright: © 2022 The Authors. Published by American Chemical Society.

Keywords

antimicrobial activity, mutagenicity, raffinose, toxicity, triandrin, water extract, willow bark

DOI

10.1021/acs.jafc.1c08161

Citation

Dou , J , Ilina , P , Hemming , J , Malinen , K , Mäkkylä , H , Oliveira De Farias , N , Tammela , P , De Aragão Umbuzeiro , G , Räisänen , R & Vuorinen , T 2022 , ' Effect of Hybrid Type and Harvesting Season on Phytochemistry and Antibacterial Activity of Extracted Metabolites from Salix Bark ' , Journal of Agricultural and Food Chemistry , vol. 70 , no. 9 , pp. 2948–2956 . https://doi.org/10.1021/acs.jafc.1c08161

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202203282661

Collections

[article-cris] Kemian tekniikan korkeakoulu / CHEM

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