Fu X, Do T, Schmitz F J, Andrusevich V, Engel M H
Department of Chemistry and Biochemistry, and School of Geology and Geophysics, University of Oklahoma, Norman, Oklahoma 73019, USA.
J Nat Prod. 1998 Dec;61(12):1547-51. doi: 10.1021/np9802872.
Four new cyclic peptides, patellamide G (2) and ulithiacyclamides E-G (3-5), along with the known patellamides A-C (6-8) and ulithiacyclamide B (9), were isolated from the ascidian Lissoclinum patella collected in Pohnpei, Federated States of Micronesia. The planar structures of these peptides were determined from 1D and 2D 1H and 13C NMR spectra. The absolute stereochemistries of the amino acid units, except for cysteine, were assigned by chiral GC analysis of N(O)-trifluoroacetyl isopropyl ester derivatives of amino acids obtained by acid hydrolysis of the intact and ozonized peptides. The structures of ulithiacyclamides E-G (3-5) were confirmed by chemical conversion. Patellamides B (7) and C (8) exhibited in vitro modulation of multidrug resistance in CEM/VBL100 cells.
从密克罗尼西亚联邦波纳佩岛采集的海鞘扁海鞘（Lissoclinum patella）中分离出了四种新的环肽，即扁海鞘酰胺G（2）和uliithiacyclamides E - G（3 - 5），以及已知的扁海鞘酰胺A - C（6 - 8）和uliithiacyclamide B（9）。这些肽的平面结构通过一维和二维氢谱及碳谱核磁共振光谱确定。除半胱氨酸外，氨基酸单元的绝对立体化学结构通过对完整肽和经臭氧处理的肽进行酸水解后得到的氨基酸的N（O）-三氟乙酰异丙酯衍生物进行手性气相色谱分析来确定。uliithiacyclamides E - G（3 - 5）的结构通过化学转化得以确认。扁海鞘酰胺B（7）和C（8）在CEM/VBL100细胞中表现出对多药耐药性的体外调节作用。
