ナカヤマ エイコ    NAKAYAMA Eiko
   中山 榮子
   所属
環境デザイン学部 環境デザイン学科
 
生活機構研究科 環境デザイン研究専攻
 
生活機構研究科 生活機構学専攻
   職種
教授
言語種別 英語
発行・発表の年月 2020/01
形態種別 学術雑誌
査読 査読あり
標題 Enhancement of Norway spruce bark side-streams: Modification of bioactive and protective properties of stilbeneoid-rich extracts by UVA-irradiation
執筆形態 共著
掲載誌名 Industrial Crops and Products
掲載区分国外
巻・号・頁 145,pp.112150
著者・共著者 Anna-Liisa Valimaa, Eiko Nakayama et al.
概要 Bark of Norway spruce (Picea abies [L.] Karst.) trees contains large amounts of polyphenolic stilbene glucosides. Stilbene-rich bark extracts could be utilized as e.g., preservatives due to their anti-oxidative, antifungal, and antibacterial properties. As stilbenes are photosensitive compounds, ultraviolet (UV) light induces a well-known intramolecular cyclization, leading to the formation of substituted phenanthrenes via a dihydro-phenanthrene intermediate. The possible UV-induced changes in the biological activities of the stilbene extracts remain, however, poorly known. Such information is crucial for practical application development. This study elucidated for the first time, how UVA-treatments of spruce bark extracts affect the chemical composition of the extracts, and further change their antimicrobial and anti-oxidative activities. Norway spruce inner bark was extracted ('Extract') and soluble mono- and disaccharides removed using Amberlite XADHP7 ('Extract XAD'). These extracts were then treated with UVA-light ('Extract UV', 'Extract XAD UV'), and chemical properties analyzed by GC/MS and HP-SEC. The antimicrobial activities of untreated and modified extracts against Staphylococcus aureus, Candida albicans, and Escherichia coli, were evaluated. Additionally, differences in the antioxidant activity between the untreated and UV-treated bark extracts were measured at a total stilbene concentration of 0.5 mg/mL EtOH, using the FRAP and ORAC methods. Also, antioxidant effects were evaluated in a liposome model to assess the ability of the extract to prevent lipid oxidation. Our novel results show that UVA-induced modification of the stilbene-rich inner bark extracts increased the radical scavenging activity. However, UVA-irradiation decreased the capacity of the extracts to prevent lipid oxidation in the liposome system method. The results also indicate a maintained or slightly increased antimicrobial activity after UVA-modification. This study shows that Norway spruce bark stilbenoids and the compounds formed by UVA-irradiation thereof show biological activity, and thus have commercial potential as e.g., preservatives.