RESUMO
A new lipopeptide, N-desmethylmajusculamide B (1), was isolated from the Okinawan cyanobacterium Okeania hirsuta along with 2 known compounds majusculamide A (2) and majusculamide B (3). The planar structure of (1) was elucidated by a detailed analysis of mass spectrometry and nuclear magnetic resonance spectra. The absolute configurations of the amino acid residues were determined using Marfey's analysis. The configuration of C-16 in the α-methyl-ß-keto-decanoyl moiety was determined unambiguously to be S by conducting a semisynthesis of N-desmethylmajusculamide B from 3. The cytotoxicity against mouse L1210 leukemia cells was evaluated for majusculamides (1-3).
Assuntos
Cianobactérias , Lipopeptídeos , Cianobactérias/química , Camundongos , Animais , Lipopeptídeos/química , Lipopeptídeos/isolamento & purificação , Lipopeptídeos/farmacologia , Linhagem Celular Tumoral , Antineoplásicos/química , Antineoplásicos/farmacologia , Antineoplásicos/isolamento & purificação , Espectroscopia de Ressonância MagnéticaRESUMO
Trihydroxy fatty acids are oxidative metabolites of polyunsaturated fatty acids isolated from plants, bacteria, fungi, and microalgae and have a variety of biological activities. In this study, a new trihydroxy fatty acid, okeanic acid-A (1), was isolated together with malyngic acid (2) and 15,16-dihydromalyngic acid (3) from the cyanobacterium Okeania hirsuta collected in Okinawa, Japan. The planar structure of 1 was elucidated by detailed analyses using high-resolution ESI-MS and 1D and 2D NMR spectroscopy. The absolute configurations of the hydroxy groups in 1 were determined unambiguously by chemical derivatisation and a modified Mosher's method. These cyanobacterial trihydroxy fatty acids (1-3) have identical configurations at their respective trihydroxy parts. Okeanic acid-A (1) showed mild growth-inhibitory activity against the marine diatom Nitzschia amabilis.