ABSTRACT
The marine-derived filamentous fungus Asteromyces cruciatus 763, obtained off the coast of La Jolla, San Diego, USA, yielded the new pentapeptide lajollamide A (1), along with the known compounds regiolone (2), hyalodendrin (3), gliovictin (4), ¹N-norgliovicitin (5), and bis-N-norgliovictin (6). The planar structure of lajollamide A (1) was determined by Nuclear Magnetic Resonance (NMR) spectroscopy in combination with mass spectrometry. The absolute configuration of lajollamide A (1) was unambiguously solved by total synthesis which provided three additional diastereomers of 1 and also revealed that an unexpected acid-mediated partial racemization (2:1) of the L-leucine and L-N-Me-leucine residues occurred during the chemical degradation process. The biological activities of the isolated metabolites, in particular their antimicrobial properties, were investigated in a series of assay systems.
Subject(s)
Anti-Infective Agents/pharmacology , Aquatic Organisms/metabolism , Fungi/metabolism , Peptides, Cyclic/pharmacology , Anti-Infective Agents/chemistry , Anti-Infective Agents/isolation & purification , California , Magnetic Resonance Spectroscopy , Mass Spectrometry , Peptides, Cyclic/chemistry , Peptides, Cyclic/isolation & purification , StereoisomerismABSTRACT
As part of the Panama International Cooperative Biodiversity Groups (ICBG) project, two new (2, 4) and two known (1, 3) linear alkynoic lipopeptides have been isolated from a Panamanian strain of the marine cyanobacterium Lyngbya majuscula. Carmabin A (1), dragomabin (2), and dragonamide A (3) showed good antimalarial activity (IC50 4.3, 6.0, and 7.7 microM, respectively), whereas the nonaromatic analogue, dragonamide B (4), was inactive. The planar structures of all four compounds were determined by NMR spectroscopy in combination with mass spectrometry, and their stereoconfigurations were established by chiral HPLC and by comparison of their optical rotations and NMR data with literature values.
Subject(s)
Antimalarials/isolation & purification , Antimalarials/pharmacology , Cyanobacteria/chemistry , Oligopeptides/isolation & purification , Oligopeptides/pharmacology , Plasmodium falciparum/drug effects , Animals , Antimalarials/chemistry , Chlorocebus aethiops , Marine Biology , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Oligopeptides/chemistry , Panama , Vero CellsABSTRACT
Nine known alkaloids [(+)-isodomesticine (1), (+)-norisodomesticine (2), (+)-nantenine ( 3), (+)-neolitsine (4), (+)-lirioferine (5), (+)-N-methyllaurotetanine (6), (+)-norlirioferine (7), (+)-isoboldine (8) and (+)-reticuline (9)] were isolated from young leaves of Guatteria dumetorum. Their structures were confirmed by NMR, mass and UV spectral analysis and by comparison to literature data. The growth inhibitory activity of each alkaloid was determined against the parasite Leishmania mexicana. Compounds 1-4 all showed significant activity whereby potency increased when a methylenedioxy functionality was present, especially at the 1,2-positions.
