The flavonoids of the rhizomes ofRhodiola rosea. II. A flavonolignan and glycosides of herbacetin
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- Zapesochnaya, G.G. & Kurkin, V.A. Chem Nat Compd (1983) 19: 21. doi:10.1007/BF00579955
Three new derivatives of herbacetin (3,4′,5,7,8-pentahydroxyflavone) have been isolated from the rhizomes of roseroot sedum for the first time. Conclusions concerning their structures have been drawn on the basis of chemical transformations and UV, PMR, and mass spectra. The structure of herbacetin 7-O-α-rhamnopyranoside is proposed for rhodionin (I). Rhodiosin (II) has the structure of herbacetin 7-O-(3″-O-β-D-glucopyranosyl-α-L-rhamnopyranoside). The biose of which it contains a residue, which has been called rhodiose, is the first example of a 3-O-β-D-glucopyranosyl-L-rhamnopyranose residue to be found in natural flavonoid glycosides. A probable structure is put forward for the flavonolignan rhodiolin (III) — the product of the oxidative coupling of coniferyl alcohol with the 7,8-dihydroxy grouping of herbacetin.