Doubly prenylated tryptamines: cytotoxicity, antimicrobial activity and cyclisation to the marine natural product flustramine A
作者:Santosh Kumar Adla、Florenz Sasse、Gerhard Kelter、Heinz-Herbert Fiebig、Thomas Lindel
DOI:10.1039/c3ob40896e
日期:——
The marine natural product flustramine A was synthesised via oxidative cyclisation of Nb-methylated 1-prenyl-2-tert-prenyl-6-bromotryptamine and subsequent reduction of the resulting amidinium salt. Only the tert-prenyl group migrated, whereas the 1-prenyl group remained in place. Interestingly, the 2-tert-prenylated precursor revealed to be the biologically most active of our entire series of 21 compounds. Required for cytotoxicity and antimicrobial activity was the presence of a non-cyclised tryptamine side chain carrying a free secondary amine, whereas the presence of a 6-bromo substituent did not enhance cytotoxicity. In a panel of 42 human tumor cell lines, most sensitive were the lung and mammary cancer cell lines LXFA629L (IC50 1.9 μM) and MAXF401NL (IC50 2.4 μM), respectively. In a serial dilution assay, satisfying IC50 values of 5.9 μM against Micrococcus luteus and 7.7 μM each against Mycobacterium phlei were determined for Nb-methyl-1-prenyl-2-tert-prenyl-6-bromotryptamine.
海洋天然产物flustramine A是通过N-甲基化1-异戊烯基-2-叔异戊烯基-6-溴色胺的氧化环合反应合成,随后还原所得的脒盐制得的。只有叔异戊烯基发生了迁移,而1-异戊烯基保持原位。有趣的是,2-叔异戊烯基前体显示出是我们21个化合物中生物活性最强的。细胞毒性和抗菌活性需要一个非环化的色胺侧链携带一个自由的二级胺,而6-溴取代基的存在并未增强细胞毒性。在对42种人体肿瘤细胞系的测试中,最敏感的是肺和乳腺癌细胞系LXFA629L(IC50 1.9 μM)和MAXF401NL(IC50 2.4 μM)。在连续稀释实验中,Nb-甲基-1-异戊烯基-2-叔异戊烯基-6-溴色胺对藤黄微球菌的IC50值为5.9 μM,对草分枝杆菌为7.7 μM。