Two new malyngamides from a Madagascan Lyngbya majuscula.
The lipid extract of a Madagascan Lyngbya majuscula has yielded malyngamides Q and R, both amides of 7-methoxytetradec-4-enoic acid. The isolation of these metabolites was accomplished using preparative liquid chromatography, with final purification through repetitive reversed-phase HPLC. Structure elucidation was accomplished utilizing 1D and 2D NMR spectroscopic characterization of the natural products and comparisons with malyngamides A and B. DPFGSE 1D NOE data suggested a different geometrical stereochemistry at C-6 in malyngamides Q and R from that observed for malyngamide A, as well as the other known malyngamides. The Z stereochemistry was confirmed for malyngamide R by measurement of key diagnostic (3)J(CH) couplings utilizing the HSQMBC pulse sequence. The absolute stereochemistry of C-4' ' of the pyrrolidone ring was defined by chiral GCMS analysis of serine released by ozonolysis and acid hydrolysis.
College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, USA.
K E
KE
Milligan
B
B
Márquez
R T
RT
Williamson
M
M
Davies-Coleman
W H
WH
Gerwick
D000577:Amides / Q000737:chemistry / Q000302:isolation & purification*; D000458:Cyanobacteria / Q000737:chemistry*; D015394:Molecular Structure; D011758:Pyrroles / Q000737:chemistry / Q000302:isolation & purification*; D013057:Spectrum Analysis
D000577:Amides; D011758:Pyrroles; C413034:malyngamide Q; C413035:malyngamide R