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《Acta Pharmaceutica Sinica》 1985-01
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STUDIES ON ~1H-NMR CHANGE AT DIFFERENT TEMPERATURES AND ~(13)C-NMR T_1 OF POLYPHASE (139)

ZHENG Jun-Min, GU Xue-Qiu, ZHANG Er-Zhi and Yang Hong(Shenyang College of Pharmacy; Liaoning Provincial Center of Physical & Chemical Analysis, Shenyang)  
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—CH_3(0.88) and—(CH_2)_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 ~(13)CNMR spectra cf polyphase liposome (139) were observed, we found that the relaxation time of ~(13)carbon nuclei T_1 increased along the alkyl chains towards the terminal methyl group. When comparisons were made between liposomes and lecithin, a smaller T_1 value of the terminal methyl group and a larger T_1 value of—N(CH_3)_3 group were obtained for the former. This indicates that the terminal methyl group is less mobile and the—N(CH_3)_3 group has a higher degree of mobility compared with the lecithin in H_2OAll the measurements were performed on Jeol-FX60 QNMR.
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