Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.
Foodwest, Kärryväylä 4, FI-60100 Seinäjoki, Finland.
Molecules. 2021 Feb 16;26(4):1036. doi: 10.3390/molecules26041036.
Stilbenes or stilbenoids, major polyphenolic compounds of the bark of Norway spruce ( L. Karst), have potential future applications as drugs, preservatives and other functional ingredients due to their antioxidative, antibacterial and antifungal properties. Stilbenes are photosensitive and UV and fluorescent light induce to isomerisation via intramolecular cyclization. So far, the characterizations of possible new compounds derived from -stilbenes under UV light exposure have been mainly tentative based only on UV or MS spectra without utilizing more detailed structural spectroscopy techniques such as NMR. The objective of this work was to study the stability of biologically interesting and readily available stilbenes such as astringin and isorhapontin and their aglucones piceatannol and isorhapontigenin, which have not been studied previously. The effects of fluorescent and UV light and storage on the stability of stilbenes were assessed and the identification and characterisation of new compounds formed during our experiments were carried out by chromatographic (HPLC, GC) and spectroscopic techniques (UV, MS, NMR). The stilbenes undergo a to isomerisation under extended UV irradiation by intramolecular cyclisation (by the formation of a new C-C bond and the loss of two hydrogens) to phenanthrene structures. The characterised compounds are novel and not described previously.
松脂素或芪类化合物是挪威云杉（L. Karst）树皮中的主要多酚类化合物，由于其抗氧化、抗菌和抗真菌特性，具有作为药物、防腐剂和其他功能性成分的潜在未来应用。芪类化合物对光敏感，紫外线和荧光会通过分子内环化诱导其异构化。到目前为止，对紫外线照射下可能从 - 芪类化合物衍生的新化合物的特征主要是基于 UV 或 MS 光谱进行推测，而没有利用更详细的结构光谱技术，如 NMR。本工作的目的是研究生物上有趣且易于获得的芪类化合物的稳定性，如缩合单宁和异落叶松脂素，以及它们的苷元 piceatannol 和异落叶松脂素，这些化合物以前没有研究过。评估了荧光和紫外光以及储存对芪类化合物稳定性的影响，并通过色谱（HPLC、GC）和光谱技术（UV、MS、NMR）对实验过程中形成的新化合物进行了鉴定和表征。芪类化合物在长时间的紫外线照射下通过分子内环化（形成新的 C-C 键和失去两个氢）发生 a 到 异构化，生成菲结构。所鉴定的化合物是新颖的，以前没有描述过。
