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Leaves of Crataegus sinaica Boiss, contain the new C-glycosyl flavone 3',4'-di-O-acetyl-2-O-α-rhamnosylvitexin, together with the hitherto unknown, dihydroflavonol 3-O-xyloside, (2R:3R)-dihydroquercetin-3-O-β- xylopyranoside. The known compounds (+)-catechin, (-)-epicatechin, vicenin- II, 2-O-α-rhamnosylvitexin, and 4'-O-acetyl-2-O-α-rhamnosylvitexin were also characterized. Structures were established by conventional methods of analysis and confirmed by 1H-, 13C-NMR, and ESI-MS.

NMR, ESI-MS, leaves, rosaceae, (2R:3R)-dihydroquercetin 3-O-β-xylopyranoside, 3', 4'-di-O-acetyl-2-O-α-rhamnosylvitexin, C-glycosyl flavones, Crataegus sinaica, dihydroflavonol 3-O-xyloside

Journal NLM ID: 9714997
Publisher: Seoul, Korea: Korean Society of Pharmacognosy
Institutions: Faculty of Science, Zagazig University, Zagazig, Egypt
Methods: 13C NMR, 1H NMR, ESI-MS, acid hydrolysis, UV, extraction, CC

7-O-Methyltetrahydroochnaflavone (1), a new biflavanone, together with nine known flavonoids, afrormosin (2), 2,3-dihydroochnaflavone 7-O-methyl ether (3), kaempferol (4), 2,3-dihydroochnaflavone (5), ochnaflavone (6), (-)-epicatechin (7), kaempferol 3-O-rhamnoside (8), taxifolin 3-O-rhamnoside (9), and kaempferol 3-O-glucoside (10), were isolated from the leaves of Ochna beddomei, and the structures were elucidated by spectral and chemical studies.

flavonoid glycosides, leaves, Ochna beddomei, 7-O-methyltetrahydroochnaflavone, biflavanone

NCBI PubMed ID: 10785425
Publication DOI: 10.1021/np9902993
Journal NLM ID: 7906882
Publisher: American Society of Pharmacognosy
Correspondence: Gunasekar D
Institutions: Natural Products Division, Department of Chemistry, Sri Venkateswara University, Tirupati, India, Dr. Reddy’s Research Foundation, Hyderabad, India, Laboratoire de Chimie des Substances Naturelles, URA 401 CNRS, Museum National d’Histoire Naturelle, Paris, France
Methods: 13C NMR, 1H NMR, EI-MS, NMR-2D, IR, UV, extraction, optical rotation measurement, CD, CC, melting point determination, evaporation, HR-FAB-MS

Grape stems contain significant amounts of polyphenolic compounds, especially phenolic acids, flavonols, and flavanonols such as astilbin. The tannin content was characterized after the depolymerization reaction thiolysis. Tannins consisted of polymeric proanthocyanidins (up to 27 units) mainly consisting of (-)-epicatechin units along with smaller amounts of (+)-catechin, (-)-epicatechin gallate, and (-)-epigallocatechin. Flavanonols (astilbin) have been identified for the first time in stem and characterized by LC/MS and NMR. All phenolic compounds in grape stems were quantified by HPLC: quercetin 3-glucuronide was the most important, followed by catechin, caffeoyltartaric acid, and dihydroquercetin 3-rhamnoside (astilbin). Comparison was made of proanthocyanidin characteristics in different white and red grape varieties and also among parts of the cluster (skin, seed, and stem). Stem-condensed tannins were qualitatively intermediate between seed and skin but could not be differentiated between red and white varieties.

grape; stems; proanthocyanidins; flavanols; flavonols; flavanonols; phenolic acids

NCBI PubMed ID: 10775352
Publication DOI: 10.1021/jf991171u
Journal NLM ID: 0374755
Publisher: American Chemical Society
Correspondence: souquet@ensam.inra.fr
Institutions: ISVV-INRA, Institut des Produits de la Vigne, Unité de Recherche Biopolymères et Arômes, Montpellier, France
Methods: 13C NMR, 1H NMR, NMR-2D, TLC, enzymatic hydrolysis, acid hydrolysis, HPLC, optical rotation measurement, HR-FAB-MS