利用native chemical ligation 方式修飾樹枝狀高分子及 於藥物輸送上的應用

Synthesis of peptide-modified dendrimers through native chemical ligation as drug carrier

巫政融(Cheng-Jung Wu)

指導教授 ： 高佳麟

高雄醫學大學/生命科學院/醫藥暨應用化學研究所/碩士(2009年)

摘要

利用藥物載體，如多價離子高分子、微胞，或是樹狀高分子微載體來輸送藥物，文獻上已有記載。藥物載體的優勢除了可利用化學修飾方式，增加藥物對患部的專一性外，亦可藉由載體的體積間接提高藥物分子的大小，使藥物不易被腎臟代謝，且更容易進入病變細胞中。然而截至目前為止，載體對於藥物釋放的專一性仍舊不足。因此本論文的目的在於加強藥物載體之專一性釋放，並探討修飾前後對藥物載體包覆量的影響。並以前列腺特異抗原(PSA)為例，利用可被PSA辨識且水解的胺基酸序列SSYYSG，修飾作為藥物載體的樹枝狀高分子(dendrimer)表面，增加載體體積，以提高專一性並提升載體藥物攜帶量。前列腺發生病變時，血漿中PSA濃度會異常上升，當以特定胺基酸序列GRLSSYYSGCGGG修飾的樹枝狀高分子輸送至患部時，大量的PSA可辨識並進一步水解序列，造成樹枝狀高分子的體積驟降，進而使載體的藥物攜帶能力下降，藉此達到專一性釋放。然而胺基酸序列合成不易，隨著序列的長度增長，在合成與純化上皆有一定的困難。有鑑於此，利用接合方式合成所要的胺基酸序列，比起直接合成後再純化要來的簡單快速。接合方式是利用1994年所發展的native chemical ligation (NCL) 接合GRLSSYYSG與CGGG兩段序列。而兩段序列的純化，已發展出一套可靠的流程，並以核磁共振光譜與質譜鑑定。而在藥物釋放部分，為探討用以修飾樹枝狀高分子表面，氨基酸序列之長度對藥物包覆量的影響，利用序列GRLSSYYSG修飾第二代、第三代與第四代PAMAM-dendrimers，並和未修飾樹枝狀高分子的藥物攜帶能力比較。

關鍵字

樹枝狀高分子 ； 藥物載體 ； 接合 ； 胜肽

並列摘要

One of the important features for drug delivery is drug carrier. Hitherto, there are a variety of drug carriers, including ionic polymer, micelle and dendrimers. Drug carrier not only achieves the purpose of targeting delivery, but also increase volume of drug, so that prolong the duration by diminish the secretion from kidney. Unfortunately, the ability to release the carried drug at specific site is not well-studied until now. The objective of this thesis is to design a novel drug carrier for specific release. Accordingly, prostate specific antigen (PSA) was selected as platform to demonstrate this principle and a specific peptide with sequence of SSYYSG, which is proved as ligand of PSA, was introduced to the surface of dendrimer. While the presence of PSA, the dendrimers functionalized with GRLSSYYSGCGGG will be hydrolyzed and causes the size of dendrimers shrinks. We postulate the carrying drug will be free due to the decreasing of volume.
Despite of the applying of solid-phase-peptide-synthesis, the preparation and purification of long peptides remains challenge. To avoid the tedious purification process, ligation strategy was applied to reduce the synthetic effort. We have developed a reliable protocol for manually solid phase peptide synthesis, and the desired peptides GRLSSYYSG and CGGG has been prepared and identified by NMR and mass spectrum. Regarding to the drug release experiment, we modify the dendrimer surface by peptide sequence for found the relationship between the volume of drug carrier and the amount of encapsulated. We have coupled G:2-4 PAMAM dendrimers with the GRLSSYYSG peptide, meanwhile, compared the volume of encapsulated with commercial PAMAM dendrimer.

並列關鍵字

dendrimer ； drug carrier ； native chemical ligation ； peptide

參考文獻

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