1. Complex C-glycosyl flavonoid phytoalexins from Cucumis sativus.
- Author
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McNally DJ, Wurms KV, Labbé C, Quideau S, and Bélanger RR
- Subjects
- Flavonoids chemistry, Flavonoids pharmacology, Fungi drug effects, Glycosides chemistry, Glycosides pharmacology, Manitoba, Molecular Structure, Nuclear Magnetic Resonance, Biomolecular, Plant Extracts chemistry, Plant Extracts pharmacology, Plant Leaves chemistry, Sesquiterpenes, Stereoisomerism, Terpenes, Phytoalexins, Cucumis sativus chemistry, Flavonoids isolation & purification, Glycosides isolation & purification, Plant Extracts isolation & purification, Plants, Medicinal chemistry
- 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.
- Published
- 2003
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