Smenamides are an intriguing class of peptide/polyketide molecules of marine origin showing antiproliferative activity against lung cancer Calu-1 cells at nanomolar concentrations through a clear pro-apoptotic mechanism. To probe the role of the activity-determining structural features, the 16-epi-analogue of smenamide A and eight simplified analogues in the 16-epi series were prepared using a flexible synthetic route. The synthetic analogues were tested on multiple myeloma (MM) cell lines showing that the configuration at C-16 slightly affects the activity, since the 16-epi-derivative is still active at nanomolar concentrations. Interestingly, it was found that the truncated compound 8, mainly composed of the pyrrolinone terminus, was not active, while compound 13, essentially lacking the pyrrolinone moiety, was 1000-fold less active than the intact substance and was the most active among all the synthesized compounds.
Totalsynthesis of modified pentapeptide, caldoramide, a cytotoxic linear pentapeptide from the marine cyanobacterium Caldora penicillate is described. Notable features of the route include the efficient preparation of three key fragments and final assembly to the natural product via sequential amide couplings. The spectral data of the synthetic compound was found to be in comparison with that of the
natural pyrrolidone derived from phenylalanine, for the first time as a single compound. Compound 1, with an (S)‐l absolutestereochemistry, was previously identified as a substructure that is common among several bioactive natural peptides. Surprisingly, the absolutestereochemistry of the isolated natural 1, determined through total synthesis, was (R)‐d. This result was unambiguously determined by
Synthesis and anticancer activity of the proposed structure of caldoramide, an N-peptidyltetramate from the cyanobacterium Caldora penicillata
作者:Anja Wunder、Matthias Rothemund、Rainer Schobert
DOI:10.1016/j.tet.2018.04.004
日期:2018.9
The structure proposed in the literature for caldoramide, a formal pentapeptide metabolite of the marine cyanobacterium Caldora penicillata, was synthesised in 12 steps and 16% yield (longest linear sequence from isoleucine) following the strategy of a stepwise consecutive extension of an N-oligopeptidyl chain on a tetramate anchor. The synthetic product differed from the natural isolate in optical rotation, some NMR data, and cytotoxicities. Its antiproliferative effect on three human cancer cell lines was distinctly lower than that of related dolastatin 10 and belamide A. (C) 2018 Elsevier Ltd. All rights reserved.
A Flexible Asymmetric Approach to Methyl 5-Alkyltetramates and Its Application in the Synthesis of Cytotoxic Marine Natural Product Belamide A
By using a methyl tetramate derivative (R)‐ or (S)‐9 as a novel chiral building block, a direct, flexible, and highly enantioselective approach to methyl (R)‐ or (S)‐5‐alkyltetramates (2) is disclosed. Among the synthesized methyl 5‐alkyltetramates 2, methyl 5‐methyltetramate (2 a) is found in cytotoxic mirabimide E (4) and dysideapyrrolidone (5), and methyl 5‐benzyltetramate (2 g) is a substructure
通过使用四甲基甲酸酯衍生物(R)‐或(S)‐9作为新型手性结构单元,可以直接,灵活且高度对映选择性地合成四甲基(R)‐或(S)‐5‐烷基四酸酯(2)。披露。在合成的5-烷基四酸甲酯2中,在细胞毒性的mirabimide E(4)和dysideapyrrolidone(5)中发现了5-甲基四酸甲酯(2 a),而5-苄基四酸甲酯(2 g)是有效的抗肿瘤药物dolastatin 15中的子结构。 (3)。在此方法的基础上,从(S)-9的七个步骤完成了抗有丝分裂四肽belamide A(7)的首次不对称合成,总收率为23.8%。不仅确认了(+)-belamide A(7)的结构和绝对构型,还确认了用于记录13 C NMR光谱,13 C NMR光谱数据相关性和天然belamide A的旋光度数据的溶剂。 (7)已被修改。