Isolation and synthesis of falcitidin, a novel myxobacterial-derived acyltetrapeptide with activity against the malaria target falcipain-2
作者:Brinda Somanadhan、Santosh R Kotturi、Chung Yan Leong、Robert P Glover、Yicun Huang、Horst Flotow、Antony D Buss、Martin J Lear、Mark S Butler
DOI:10.1038/ja.2012.123
日期:2013.5
A 384-well microtitre plate fluorescence cleavage assay was developed to identify inhibitors of the cysteine protease falcipain-2, an important antimalarial drug target. Bioassay-guided isolation of a MeOH extract from a myxobacterium Chitinophaga sp. Y23 isolated from soil collected in Singapore, led to the identification of a new acyltetrapeptide, falcitidin (1), which displayed an IC50 value of 6âμM against falcipain-2. The planar structure of 1 was secured by NMR and MS/MS analysis. Attempts to isolate further material for biological testing were hampered by inconsistent production and by a low yield (<100âμg lâ1). The absolute configuration of 1 was determined by Marfeyâs analysis and the structure was confirmed through total synthesis as isovaleric acid-D-His-L-Ile-L-Val-L-Pro-NH2. Falcitidin (1) is the first member of a new class of falcipain-2 inhibitors and, unlike other peptide-based inhibitors, does not contain reactive groups that irreversibly bind to active cysteine sites.
开发了一种384孔微量滴定板荧光切割测定法,用于鉴定半胱氨酸蛋白酶falcipain-2的抑制剂,falcipain-2是一个重要的抗疟药物靶点。通过生物活性导向分离自新加坡采集的土壤中分离得到的粘细菌Chitinophaga sp. Y23的甲醇提取物,鉴定出一种新的酰基四肽falcitidin(1),其对falcipain-2的IC50值为6μM。通过NMR和MS/MS分析确定了1的平面结构。由于产量低且不稳定(<100μg/L),尝试分离更多用于生物测试的样品受到阻碍。通过Marfey分析确定了1的绝对构型,并通过全合成确认其结构为异戊酸-D-组氨酸-L-异亮氨酸-L-缬氨酸-L-脯氨酸-NH2。Falcitidin(1)是新型falcipain-2抑制剂的首个成员,与其他基于肽的抑制剂不同,它不含有与活性半胱氨酸位点不可逆结合的反应性基团。