Ribes alpinum L. (alpine currant) (Grossulariaceae), is a shrub widespread in montainous areas across western Europe. Unlike R. nigrum (black currant), R. rubrum (red currant) and R. grossularia (gooseberry), this species is not cultivated to-day, although its berries collected in the wild were traditionally used to prepare a cheap 'wine'. Renewed attention is currently being given to these species as part of the revival of 'natural' food sources and the search for their valorization as pharmaceuticals; here the use of leaf infusions in traditional medicine draws attention to their polyphenolic content, such molecules being the active components of many commercialized plant preparations. While hydrolysates from R. nigrum and other species are currently screened for their antioxydant flavonols, such work deals mainly with the edible berries.1,2) As for the leaves, most knowledge dates from chemotaxonomic surveys of flavonol aglycones 3,4) ; sampling investigated for native O-glycosides is very limited.5-7) As part of a multidisciplinary analysis of regional wild and cultivated Ribes biodiversity, the flavonoid pattern of leaves from 120 individual plants, half representing R. alpinum, was assessed. HPLC coupled with PDA detection revealed that R. alpinum differed from the other species under study, in agreement with its botanical assignment to subgenus Berisia (Leclerc et al., to be published). We report here the isolation and structural elucidation of the six major flavonol glycosides characteristic of the leaves of R. alpinum, three of which were hitherto undescribed. A phloracetophenone glycoside was also isolated.The ethanolic extract of dried leaves from R. alpinum, once defatted, was fractionated by a combination of gel filtration and chromatographic techniques including cellulose preparative TLC and diol-bonded silica CC to give 1-7.Analysis of the 1 H-and 13 C-NMR spectra of compound 1 (Table 1; all assignments based on HSQC-TOCSY and HMBC experiments) showed the presence of one aromatic and one aliphatic system as well as a sugar moiety. The 1 H-NMR resonances of two meta coupled doublets at d 6.23 and 6.40 ppm (1H, Jϭ1.9 Hz), correlated with the carbons at 99.7 and 94.7 ppm respectively in the HSQC spectrum, characterized the 6-and 8-protons of a flavonoid 5, 7 dihydroxy Aring.8) The doublet at d 6.80 (2H, Jϭ0.9 Hz) was attributed * To whom correspondence should be addressed. Three new flavonol malonylrhamnosides, 3-O-(4؆-O-malonyl)-a a-L-rhamnopyranosides of mearnsetin, myricetin and quercetin respectively, together with the corresponding mearnsitrin, myricitrin, quercitrin and the 4-O-methyl phloracetophenone 2-O-b b-D-glucopyranoside, were isolated from the leaves of Ribes alpinum and fully characterized by spectrocopic methods including 2D NMR.
