Synthesis and structure–activity relationship studies of novel tubulysin U analogues – effect on cytotoxicity of structural variations in the tubuvaline fragment
作者:Sreejith P. Shankar、Monika Jagodzinska、Luciana Malpezzi、Paolo Lazzari、Ilaria Manca、Iain R. Greig、Monica Sani、Matteo Zanda
DOI:10.1039/c3ob27111k
日期:——
Tubulysins are cytotoxic natural products with promising anti-cancer properties, originally isolated from myxobacterial cultures. Structurally, tubulysins are tetrapeptides, incorporating three unusual (Mep, Tuv and Tup) and one proteinogenic amino acid (Ile). Here we describe the synthesis and structureâactivity relationship studies of novel tubulysin U and V analogues, with variations in the central Tuv fragment, which is known to be of paramount importance for tubulysinsâ potency and hence cytotoxicity, but has seldom been modified in previous studies. Specifically, we replaced the natural iso-propyl and acetoxy functionalities with other structurally related groups. In general, the new analogues showed much lower potency relative to native tubulysin U. However, one of the synthetic analogues (1f) having a MOM function replacing the acetyl group exhibited a 22 nM IC50 on the HT-29 cell line which is comparable to the IC50 displayed by tubulysin U (3.8 nM). Furthermore, the synthetic methodology reported herein was found to be flexible enough to deliver different core-modified tubulysin analogues and hence may be regarded as a scalable and convenient strategy for the chemical generation of novel tubulysin analogues.
Tubulysins是一种细胞毒性天然产物,具有有前景的抗癌特性,最初从粘细菌培养物中分离出来。在结构上,Tubulysins是四肽,包含三个不寻常的(Mep、Tuv和Tup)和一个蛋白质原生的氨基酸(Ile)。在这里,我们描述了新型Tubulysin U和V类似物的合成及其构效关系研究,这些类似物在中央Tuv片段上有所变化,该片段对于Tubulysins的效力和细胞毒性至关重要,但在先前的研究中很少被修改。具体而言,我们用其他结构相关的基团替代了天然的异丙基和乙酰氧基功能。总的来说,与天然Tubulysin U相比,新的类似物显示出较低的效力。然而,其中一个合成类似物(1f)具有MOM功能替代乙酰基,在HT-29细胞系上显示出22 nM的IC50,与Tubulysin U(3.8 nM)显示的IC50相当。此外,本文报道的合成方法被发现足够灵活,可以提供不同核心修饰的Tubulysin类似物,因此可以被视为产生新型Tubulysins类似物的可扩展和便捷策略。