RC-160的碘標方法比較及其生物分布特征

摘要

目的擬建立一種高效碘標多肽RC-160的方法.方法以溴代琥珀酰亞胺(NBS) 為氧化劑,常規氯胺T法作為對照,對125I-RC-160的標記率、比活度進行評價,并觀察125I-RC-160在正常小鼠體内的生物分布特征.結果在丙酮:生理鹽水=1:1體系中,測得125I-RC-160的標記率NBS法為92%,比放射性為1.75×1012Bq/mmoL,標記率隨NBS用量增加而增高,最佳用量比為RC-160(μg):125I(MBq):NBS(μg)=3:7.4:1,且產物無需純化;Ch-T法標記率為56%.,比放射性為0.65×1012Bq/mmoL,經SepPaK-C18反向色譜柱純化,125I-RC-160的放射化學純度＞98%.標記物在血中清除較快,注射后不到1小時血中的放射性就下降了87.2%;125I-RC-160在腎内濃集度很低,主要經過消化系統排出體外.結論NBS法可高效碘標多肽,標記后無需純化,减少了對操作者的輻射,是一種碘標的理想方法.%Objective We aims to establish a method of labeling of RC-160 with 125I. Methods NBS was used as oxi dant. Ch-T method was also performed as control. Labeling yield and specific activity of 125I-RC-160 were determined.Biodistribution of 125 I-RC-160 in normal mice was observed. Results When using acetone and saline (1: 1) as developer,labeling yield and specific radioactivity of 125 I-RC-160 was 92% and 1.75 × 10 12 Bq/mmol respectively with NBS method.The labeling yield was raised with the increase of NBS dose. The optimal dose of RC-160 (g): 125I (MBq): NBS (g)was 3: 7.4: 1. The 125 I-RC-160 prepared with NBS method needed no purification. Labeling yield and specific radioac tivity of 125I-RC-160 was 56% and 0. 65 1012 Bq/mmol respectively with Ch-T method. Reverse-phase (RP) chromatog raphy was used to purify the products. Radiochemical purity of 125I-RC-160 was over 98% with Ch-T method. Radioactiv-ity of 125 I-RC-160 in blood was decreased by 87.2% within less than 1 hr, which indicated that a substantial amount of the injected dose had been cleared from blood. Very little radioactivity was found in kidney. However, much radioactivity was found in intestines, suggesting that the route of clearance of 125 I-RC-160 was digestive system. Conclusion The results re-vealed that NBS method is an ideal iodine labeling method, with high labeling efficiency, unnecessary for no further purifi cation and minimization of the radiation damage.