PROPERTIES OF o•- AND [B-GLYCYRRHIZINS 179 o • 40 .•_ 30 lO I I I I -5 -4 -3 -2 log C ( mol/I ) Figure 2. Interfacial tension of Gs at water-liquid paraffin interface (25øC). 13C-N. MR(CD3OD + CDC13): 8 20.7, 20.9 (•H3COO-), 170.8, 171.0, 171.1 (CH3COO-). Anal. Calc. for C52H72017: C, 60.45 H, 7.02. Found: C, 60.59 H, 7.12. Other chemicals used in the present study were all of reagent grade. INTERFACIAL TENSION Measurements were carried out with a Rigosha Auto Tensionmeter, Model 6801 ESD, at 25øC by the ring method. The inner diameter of the ring and the diameter of the platinum wire were 1.909 and 0.060 cm, respectively. NUCLEAR MAGNETIC RESONANCE (NMR) •C-NMR spectra were recorded on a JEOL JNM-FX 100 Spectrometer with tetra- methylsilane as the external standard. Pulse width: 10 •sec (45ø). Pulse repetition: 1.0 sec. Spectral width: 6024 Hz. SCANNING ELECTRON MICROSCOPY (SEM) A Hitachi Scanning Electron Miscroscope, Model S-450, equipped with a cryosystem

180 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ß x m O ß 2 3 4 5 6 7 pH Figure 3. pH dependence of viscosity of Gs aqueous solution (1.0 wt%, 20øC). Table I Gelling behaviors of G derivatives H3Ci,•C OO R 3 CH3 (• H3 '• 3 )-o o H i COO R 2 OH OH R1 R2 R3 gel-formation H H H /3 ++ K(H} H(K} H /3 ++ K K H /3 - K K K /3 - K(H} H (K} CH3 /• - K salt of G Pentaacetate /3 K salt of Glycyrrhetin o• J-