Two novel cyclodepsipeptides, geodiamolides A (1) and B (2), were isolated from the marine sponge Geodia sp. and their stereostructures determined by X-ray crystallography. The geodiamolides contain a tripeptide unit of two (S)-alanines and a (R)-3-halotyrosine joined to a polypropionate unit in an 18-membered ring; the halogens are iodine and bromine in 1 and 2, respectively. 1 and 2 showed some activity against the fungus Candida albicans.
Seven new labdane diterpenes, sibiricinones A-E (1-4, 6) and 15-epi-sibiricinones D and E (5 and 7), and the flavone genkwanin were isolated from the aerial parts of Leonurus sibiricus. Sibiricinone D (4) and 15-epi-sibiricinone D (5), and sibiricinone E (6) and 15-epi-sibiricinone E (7), respectively, were isolated as C-15 epimeric pairs. These secondary metabolites were identified on the basis of 1D and 2D NMR including (1)H-(1)H COSY, HSQC, and HMBC spectroscopic techniques. The stereochemical configurations of compounds 4-7 were assigned through 2D T-ROESY and selective NOE experiments.
Four cassane furanoditerpenes, designated bonducellpins
A (1), B (2), C (3), and D
(4), were
isolated from the roots of Caesalpinia bonduc. The
1H- and 13C-NMR spectra of all
four
compounds were completely assigned by using a combination of 2D NMR
experiments, which
included COSY, HMQC, HMBC, and NOESY sequences.
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