STUDIES ON ¹H-NMR CHANGE AT DIFFERENT TEMPERATURES AND ¹³C-NMR T₁ OF POLYPHASE (139)

The polyphase liposome (139) was made of soybean lecithin, cholesterol, tween, span, PVP and a vegetable constituent. Its technological characteristics were investigated by means of ¹HNMR at different temperatures. It was found that two distinct high resonances for—CH₃(0.88) and—(CH₂)_n—(1.27)appeareal from 78° to 90℃ in the upfield region of the ¹HNMR spectrum of liposomes in deuterowater. This shows that the liposome preparation produces phase change at temperatures above 78℃. However, when the preparation was cooled to room temperature, the spectrum returned to its original pattern. So the injectable preparation may be subjected to steam sterilization for large scale production.The addition of amphipathic compounds broadened the resonances of terminal methyl group, methylene group and headgroup of lecithin. When ¹³CNMR spectra cf polyphase liposome (139) were observed, we found that the relaxation time of ¹³carbon nuclei T₁ increased along the alkyl chains towards the terminal methyl group. When comparisons were made between liposomes and lecithin, a smaller T₁ value of the terminal methyl group and a larger T₁ value of—N(CH₃)₃ group were obtained for the former. This indicates that the terminal methyl group is less mobile and the—N(CH₃)₃ group has a higher degree of mobility compared with the lecithin in H₂OAll the measurements were performed on Jeol-FX60 QNMR.