AI Article Synopsis
- Researchers discovered two new C-glycosyl flavonoids, cucumerin A (1) and cucumerin B (2), in cucumber leaves that are resistant to powdery mildew fungi.
- In addition to these new compounds, they found higher levels of several known flavonoids and acids in the resistant plants, including vitexin (3) and isovitexin (4).
- The study highlights the importance of these compounds in the plant's defense mechanisms, suggesting they function as phytoalexins to protect against fungal infections.
Article Abstract
Extraction of cucumber leaf tissue expressing induced resistance against powdery mildew fungi revealed the presence of two new major C-glycosyl flavonoid products: vitexin-6-(4-hydroxy-1-ethylbenzene) (cucumerin A, 1) and isovitexin-8-(4-hydroxy-1-ethylbenzene) (cucumerin B, 2). In addition, the known C-glycosyl flavonoids apigenin-8-C-beta-D-glucopyranoside (vitexin, 3), apigenin-6-C-beta-D-glucopyranoside (isovitexin, 4), luteolin-8-C-beta-D-glucopyranoside (orientin, 5), and luteolin-6-C-beta-D-glucopyranoside (isoorientin, 6), as well as 4-hydroxycinnamic acid (p-coumaric acid, 7) and its methyl ester (p-came, 8), were found in higher quantities within resistant plants. The structures of 1-8 were elucidated using spectroscopic methods and unambiguously confirmed for 3-8 using co-chromatography experiments with authentic standards. On the basis of the results of this study and the reported biological activities of C-glycosyl flavonoids, these compounds would play a vital role in the defense strategy of this species by acting as phytoalexins.
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| http://dx.doi.org/10.1021/np030150y | DOI Listing |
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