Design and synthesis of FAJANU: a de novo C(2) symmetric cyclopeptide family.

A novel cyclic peptide has been designed from several potent marine cytotoxic peptides, including IB-01212, luzopeptin, triostin, and thiocoraline. The FAJANU scaffold maintains C 2 symmetry, cyclic structure, and the construction of aromatic and aliphatic character at the N- and C-terminal extremes. A first six-member family was previously synthesized and evaluated biologically. Several analogues presented greater activity than IB-01212. Furthermore, on the basis of the most active candidate, we have performed a more exhaustive synthetic and structural analysis: (i) structure-activity relationship provided clues about the key elements in the framework, (ii) NMR assignment confirmed C 2 symmetry, and (iii) confocal images revealed its penetration and cellular localization.