Noducyclamides A1–A4, B1, and B2 from the Cyanobacterium <i>Nodularia</i> sp. NIES-3585
Jakia Jerin Mehjabin, Chin‐Soon Phan, Tatsufumi Okino
Abstract
A chemical investigation of the hydrophilic fraction of a cultured Nodularia sp. (NIES-3585) afforded six new cyclic lipopeptides, noducyclamides A1–A4 ( 1 – 4 ) containing 10 amino acid residues and dodecapeptides noducyclamides B1 and B2 ( 5 and 6 ). The planar structures of these lipopeptides were elucidated based on the combination of HRMS and 1D and 2D NMR spectroscopic data analyses. These peptides are structurally analogous to laxaphycins and contain the nonproteinogenic amino acids 3-hydroxyvaline and 3-hydroxyleucine and a β-amino decanoic acid residue. The absolute configurations of the noducyclamides ( 1 – 6 ) were determined by acid hydrolysis, followed by advanced Marfey’s analysis. Noducyclamide B1 ( 5 ) showed cytotoxic activities against MCF7 breast cancer cell lines with an IC 50 value of 3.0 μg/mL (2.2 μM).