^(99m)Tc-depreotide异构体的分离及鉴定

Isolation and identification of Syn and anti diastereomers of ^(99m)Tc-depreotide

目的分离、鉴定99mTc-depreotide异构体,并比较其生物活性。方法采用高压液相色谱仪分离99mTc-depreotide的一对顺式和反式异构体,采用质谱、CD光谱、1 H NMR分析异构体的结构特征,比较A549细胞对这对异构体的受体亲和性。结果高压液相色谱仪分离的顺式和反式异构体的含量比约为90∶10,顺式和反式异构体的分子质量均为1 469.5,均有不同的科顿效应;1 H NMR结果可显示二者的氨基酸序列和结构特征;顺式异构体的受体亲和性明显高于反式异构体(P<0.01)。结论 99mTc-depreotide存在顺式和反式异构体,且生物活性不同,在实际应用中应将2个异构体视作2个化合物。

Objective To isolate and identify Syn and anti diastereomers of ^99mTc-depreotide, and compare the biological activity. Methods Syn and anti distereomers of ^99mTc-depreotide were isolated by HPLC, and were identified by mass spectrograph, circular dichroism spectra and ^1H NMR. The binding affinities of Syn/anti ^99mTc-depreotide to SSTRs were evaluated with A549 cells. Results Syn/anti ^99mTc-depreotide products were observed by reversed phase HPLC in approximately 90 ： 10 ratio. The mass of both distereomers was 1469. 5 corresponding to results of mass spectrograph. The different Cotton effect of the Syn/anti distereomers was observed. The amino acids and structural features of the Syn/anti distereomers were showed by 1 H NMR. The Syn diastereomer showed higher binding affinities than the anti distereomer in A549 cells （P〈0.01）. Conclusion There are a pair of Syn and anti distereomers in ^99mTc depreotide, and the Syn distereomer has higher bioactivity than anti distereomer. In practical applications the two diastereomers chould be considered as two compounds.