New 3-hydroxyflavanone (dihydroflavonol) phytoalexins from the papilionate legume Shuteria vestita.

Diffusates from the fungus-inoculated leaflets of Shuteria vestita have yielded four novel 3-hydroxyflavanone (dihydroflavonol) phytoalexins. From spectroscopic and chemical evidence, three of these phytoalexins have been identified as (2R,3R,2''R)--3,5,4'-trihydroxy-2'-isopropenyldihydrofurano (4'',5''; 6,7) flavanone (shuterol,1), (2R,3R)--3,5,7,4'-tetrahydroxy-6-(3,3-dimethylally) flavanone (shuterin, 2), and (2R,3R,2''R)--3,5,2',4'-tetrahydroxy-2''-isopropenyldihydrofurano (4'',5''; 6,7)flavanone (shuterone A, 3). The fourth compound (shuterone B, 4) is considered to be the 2S,3R stereoisomer of shuterone A.

Analysis of soybean sapogenins by high-performance liquid chromatography.

A method for the analysis of soybean sapogenins is described. The method is based on the extraction of soybean saponins from a defatted sample. The triterpene glycosides are then hydrolysed with subsequent analysis of the liberated sapogenins by high-performance liquid chromatography using gradient elution and mass detection. By use of a sapogenin/carbohydrate ratio, an estimate of the total saponin content can be made.

Structural functions of the sweet pharmacophore.

The relative sweetness, onset times, and durations of response of D-glucose, D-xylose, D-quinovose, D-galactose, L-arabinose, and D-fucose were determined at four temperatures. The results can be interpreted by simple concepts of intramolecular hydrogen bonding which indicate that the so-called gamma-function of the tripartite AH,B, gamma sweet pharmacophore plays little or no part in sugar sweetness. Probably the Lemieux effect (intramolecular hydrogen bonding between the hydroxymethyl substituent and the 4-hydroxy group) is of overriding importance in determining sugar sweetness, and the separate features of intensity and time of response indicate distinct functions of chemoreception. The absence of a gamma-function in simple hydrophilic molecules such as glucose has already been emphasized. This function distinguishes them from the artificial sweetners such as saccharin, which may be 500 times or more sweeter than sucrose, depending on their stereostructure and lipophilicity.