4348-77-0

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A new flavonol-diglycoside was isolated from the methanolic extract of the aerial parts of Melastoma melabathricum.Its structure was established as quercetin-3-O-α-L-rhamnosyl-(1->2)-β-D-galactoside on the basis of physical and chemical evidences.

Key Word Index-Euphorbia acaulis; Euphorbiaceae; 3,3'-di-O-methyl ellagic acid 4'-rutinoside; 3,4,3'-tri-O-methyl ellagic acid 4'-rutinoside.Abstract-A new ellagic acid glycoside, 3,3'-di-O-methyl ellagic acid 4'-rutinoside, along with 3,4,3'-tri-O-methyl ellagic acid 4'-rutinoside and 3,4,3'-tri-O-methyl ellagic acid have been isolated from the rhizomes of Euphorbia acaulis.The structures of these compounds have been established on the basis of spectral (1H NMR, 13C NMR, MS, IR, UV) and chemical evidence.

A new steroid glycoside of the spirostan series - taccaoside (I) - has been isolated from an ethanolic extract of the roots of Tacca cheancer (family Taccaceae).An acid hydrolysate was found to contain the aglycone diosgenin (II) and the sugars D-glucose and L-rhamnose in a ratio of 1:2.By methyletion and hydrolysis of the permethylete (IV) it has been established that the two terminal L-rhamnose residues are attached at C-2 and C-3 of the D-glucose molecule which, in its turn, substitutes the hydroxy group at C-3 of diosgenin.Glycoside (I) has the structure of (25R)-spirost-5-en-3β-ol 3-O-2)>3)>-β-D-glucopyranoside>.