ABSOLUTE STEREOSTRUCTURES OF BETAVULGAROSIDE-III AND BETAVULGAROSIDE-IV, INHIBITORS OF GLUCOSE-ABSORPTION, FROM THE ROOTS OF BETA-VULGARIS L (SUGAR-BEET)

The absolute stereostructures of betavulgarosides III and IV, which we re isolated from the roots of Beta vulgaris L. (sugar beet) and exhibi ted inhibitory activity on glucose absorption, were determined by the chemical correlation of betavulgaroside IV with a known saponin momord in I, which included the conversion from the alpha-1-arabinopyranosyl moiety of momordin I to the acidic acetal-type substituent of betavulg arosides III and IV via the alpha-L-ribopyranosyl derivative. Furtherm ore, four acidic acetal-type substituent analogues were synthesized fr om L- and D-arabinose.