PROPERTIES OF tx- AND [3-GLYCYRRHIZINS 185 shift reagents on the resonances of Gs. Lanthanide shift reagents have been widely utilized in NMR spectroscopy (8) to elucidate chemical structure or conformation of various compounds. This is due to their ability to cause a noticeable paramagnetic shift of resonance induced by the interaction between the shift reagents and a Lewis base moiety of a given molecule. Figure 6 shows CMR spectra of miceIlar solutions of Gs in which a shift reagent, Eu(fod) 3, is solubilized. As Eu(fod) 3 is oil-soluble, this reagent is adequate to probe the internal nature of micelles and thus obtain conformational infor- mation on the triterpene moiety serving as a lipophilic group. The reagent caused striking broadening of signals of the triterpene carbonyl and carboxyl carbons of or-G, which may be ascribable largely to the spin-nucleus relaxation brought about by strong interaction between Eu and carboxyl and/or carbonyl carbons. In contrast, no appreci- able broadening of signals was observed in [3-G, though a slight paramagnetic shift of resonances of triterpene carboxyl carbons was induced by the addition of the reagent. These findings strongly suggest that the carboxyl group of the triterpene moiety of is blocked by some molecular interaction, whereas that of ot-G is much more free. SEM OBSERVATIONS/AQUEOUS SOLUTIONS OF GLYCYRRHIZINS An SEM image of a lyophilized gel of [3-G is shown in Figure 7, where a regular /. : . f- Figure 8. Scanning electron micrograph image of lyophilized sample of o•-O aqueous solution (l. 0 wt%).

186 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS O CH3 ( :a CH• HO I CH:] ø•c o .... HO • ]'!%., / O, /O•,,/! 'C CHa .o .... HO' • 'OH OH Figure 9. Cyclic model of •-G in aqueous solution. lOO • 80 E • 60 c 40 • 20 0 0 I / O: Geranyl acetate •: Geraniol El .' Ionone •: Dipentene I • ß 0.5 1.0 1.5 2.0 Concentration of c•-G (wt%) øc Figure 10. Solubilizing ability of(x-G for several perfume materials (30 , pH 4.5). Ethanol: 9.95 wt%. Solubilizate: 0.05 wt%. Water + (x-G: 90.00 wt%.