Design, synthesis and evaluation of constrained methoxyethyl (cMOE) and constrained ethyl (cEt) nucleoside analogs.
Design, synthesis and evaluation of constrained methoxyethyl (cMOE) and constrained ethyl (cEt) nucleoside analogs.
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DOI：
10.1093/nass/nrn280
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发表时间：
2008-01-01
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影响因子：
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通讯作者：
Swayze, Eric E
中科院分区：
文献类型：
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作者：
Seth, Punit P;Siwkowski, Andrew;Swayze, Eric E
反义药物发现技术是调控动物基因表达的一种强有力的方法，代表了一种新的治疗平台。(1)我们先前已经证明，用LNA(3)核苷取代第二代反义寡核苷酸(ASO)中的2‘O-甲氧基乙基(MoE，2)残基可以提高某些ASO在动物中的效力。然而，伴随着肝脏毒性的风险显著增加。(2)我们假设用结合了MOE和LNA结构元素的新型核苷单体取代LNA可能在保持效力的同时减轻LNA的毒性。为此，我们设计并合成了新的核苷类似物4(S约束的MoE，S-cMOE)和5(R-约束的MoE，R-cMOE)，其中2‘O-MoE的乙链被约束在呋喃糖环的4’位置。作为SAR系列的一部分，我们还制备了核苷类似物7(S约束的乙基，S-CET)和8(R约束的乙基，R-CET)，其中cMOE核苷中的甲氧甲基被甲基取代。从廉价的商业原料出发，开发了一种以最小的层析纯化步骤高效合成核苷亚磷酰胺的方法。生物物理评价表明，cmoe和cet修饰使互补核酸与LNA具有相同的亲和力，同时大大提高了核酸酶的稳定性。对含有cmoe和cet修饰的寡核苷酸的动物生物学评价表明，与第二代MoE ASO相比，它们都具有更好的效力，与LNA相比，其毒性特征有很大改善。
Antisense drug discovery technology is a powerful method to modulate gene expression in animals and represents a novel therapeutic platform.(1) We have previously demonstrated that replacing 2'O-methoxyethyl (MOE, 2) residues in second generation antisense oligonucleotides (ASOs) with LNA (3) nucleosides improves the potency of some ASOs in animals. However, this was accompanied with a significant increase in the risk for hepatotoxicity.(2) We hypothesized that replacing LNA with novel nucleoside monomers that combine the structural elements of MOE and LNA might mitigate the toxicity of LNA while maintaining potency. To this end we designed and prepared novel nucleoside analogs 4 (S-constrained MOE, S-cMOE) and 5 (R-constrained MOE, R-cMOE) where the ethyl chain of the 2'O-MOE moiety is constrained back to the 4' position of the furanose ring. As part of the SAR series, we also prepared nucleoside analogs 7 (S-constrained ethyl, S-cEt) and 8 (R-constrained Ethyl, R-cEt) where the methoxymethyl group in the cMOE nucleosides was replaced with a methyl substituent. A highly efficient synthesis of the nucleoside phosphoramidites with minimal chromatography purifications was developed starting from cheap commercially available starting materials. Biophysical evaluation revealed that the cMOE and cEt modifications hybridize complementary nucleic acids with the same affinity as LNA while greatly increasing nuclease stability. Biological evaluation of oligonucleotides containing the cMOE and cEt modification in animals indicated that all of them possessed superior potency as compared to second generation MOE ASOs and a greatly improved toxicity profile as compared to LNA.