Xeractinol: a new flavanonol C-glucoside from Paepalanthus argenteus var. argenteus (Bongard) Hensold (Eriocaulaceae)

Abstract

Um novo composto, isolado a partir do extrato metanólico das folhas de Paepalanthus argenteus var. argenteus (Bongard) Hensold foi caracterizado como xeractinol, um novo diidroflavonol C-glucosilado. Sua estrutura foi elucidada com base em extensiva análise espectroscópica (RMN uni-e bidimensionais, EM, HREIMS, IV, UV). Cálculos ab initio de estrutura eletrônica corroboram nossa proposição para a estrutura molecular. O diidroflavonol aqui isolado pode servir como marcador taxonômico de Paepalanthus subg. Xeractis, uma vez que este flavonóide não foi encontrado em nenhum outro taxon de Eriocaulaceae.New compound isolated from methanolic extract from the leaves of Paepalanthus argenteus var. argenteus (Bongard) Hensold was characterized as xeractinol, a new dihydroflavonol C-glucoside. The structure was elucidated on the basis of extensive spectroscopic analysis (1D and 2D NMR, MS, HREIMS, IR and UV). Ab initio electronic structure calculations support our proposal to the molecular structure. The dihydroflavonol herein isolated may serve as taxonomic marker of Paepalanthus subgenus Xeractis, because this flavonoid have not been reported in any other taxon of Eriocaulaceae.

Characterization of Flavonoids and Naphthopyranones in Methanol Extracts of Paepalanthus chiquitensis Herzog by HPLC-ESI-IT-MSn and Their Mutagenic Activity

“…This dihydroflavonol served as a taxonomic marker of Paepalanthus subg. xeractis [ 26 ]. Since such flavanonols have been identified in P. chiquitensis , we suggest that this class of compounds can be of use in the chemotaxonomy of Paepalanthus .…”

Insights into the Phytochemistry of the Cuban Endemic Medicinal Plant Phyllanthus orbicularis: Fideloside, a Novel Bioactive 8-C-glycosyl 2,3-Dihydroflavonol

“…MS/MS fragmentation of the precursor ion at m / z 465.1039 [M-H] − gives rise to a m / z 345.0620 [(M − H) − 120] − fragment, generated by the cleavage in the glycoside portion on position 2″. These data are consistent with a C-type glycosidic structure [34,35]. Further MS/MSof m / z 345 generates ions at m / z 179and 167 resulting from the retro-Diels–Alder fragmentation of flavonoid ring C, indicating the position of the glycoside moiety to be on ring A.…”

New flavonoids and other constituents from Ouratea hexasperma (Ochnaceae)

“…The presence of γ,γ-dimethylallyl group was identified by two signals of three-protons at d 1.75 and 1.61 (-CMe 2 ), multiplets at d 3.31, 3.14 (CH 2 -CH=C<), and the signal at d 5.17 (t, 7.0 Hz, CH 2 -CH=C<). The 13 C NMR chemical shifts of the prenyl group (C-1'"-5'"), the d CH at 94.2 (CH-8) and d C at 199.7 (C-4) and 109.9 (C-6) detected in the 13 C NMR (BBD and DEPT) and HMQC spectra (Table 1) were compatible with this group being located at C-6 of flavononol ( Figure 1). According to the values of J H-2,H-3 11Hz, d CH-2 83.2 and d CH-3 71.8, the aryl and hydroxyl substituents at C-2 and C-3 are equatorially oriented (2,3-trans), with the same stereochemistry proposed for xeractinol.…”

“…According to the values of J H-2,H-3 11Hz, d CH-2 83.2 and d CH-3 71.8, the aryl and hydroxyl substituents at C-2 and C-3 are equatorially oriented (2,3-trans), with the same stereochemistry proposed for xeractinol. 13 The sugar moiety was identified from five additional resonances of oxymethyne carbons including a signal at d CH 100.2 (HC-1''), and of a CH 2 at 60.7 (H 2 C-6'') ( Table 1), corresponding to a O-β-D-glucopyranosyl moiety.…”

“…14 The analysis of 13 C NMR (BBD and DEPT) and HMQC spectra, and data comparison of 1 ( Table 1) Related compounds have been previously isolated from other plant species, such as 7-O-glycopyranosyl-6-prenyl-3,5,3',4'-tetrahydroxyflavanone, the only glycoside of this type isolated from Ochnaceae (Ochna integerrima), 15 7-O-glycopyranosyl-6-(3-hydroxy-3-methyl-butyl-3,5,4'-trihydroxyflavanone isolated from Phellodendron chinese (Rutaceae), 16 and the diphyllosides identified in Epimedium diphyllum (Berberidaceae). .…”