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+-Kalkitoxin, a metabolite of the marine cyanobacterium Lyngbya majuscula, was synthesized from (R)-2-methylbutyric acid, (R)-cysteine, and (3S, 4S, 6S)-3,4,6-trimethyl-8-(methylamino)octanoic acid. A key step in the synthesis was installation of the anti,anti methyl stereotriad by means of a tandem asymmetric conjugate addition of an organocopper species(More)
Two epimers of malyngamide C, 8-O-acetyl-8-epi-malyngamide C (1) and 8-epi-malyngamide C (3) have been isolated along with known compounds 6-O-acetylmalyngamide F (5), H (6), J (7) K (8), and characterized from a Grenada field collection of the marine cyanobacterium Lyngbya majuscula. The structures of these compounds were deduced by 1D and 2D NMR(More)
Azonazine, a unique hexacyclic dipeptide, was isolated from a Hawaiian marine sediment-derived fungus eventually identified as Aspergillus insulicola. Its absolute configuration, 2R,10R,11S,19R, was established using NMR, HRESIMS, and CD data plus insights derived from molecular models. A possible route for its biogenesis is proposed, and biological(More)
We investigated a small-molecule modulator of tumor necrosis factor alpha (TNF-alpha), UTL-5g (also referred to as GBL-5g), as a potential chemoprotective agent against cisplatin-induced side effects including nephrotoxicity, hepatotoxicity and hematotoxicity. Pretreatment of UTL-5g i.p. in BDF1 mice reduced the levels of blood urea nitrogen (BUN) and(More)
Bioassay-guided fractionation of Papua New Guinea collections of Leucosolenia sp. resulted in the isolation of the novel compounds leucosolenamines A (5) and B (6) and the known compound thymidine (7). Compound 5 contains a 2-aminoimidazole core substituted at C-4 and C-5 by an N,N-dimethyl-5,6-diaminopyrimidine-2,4-dione and a benzyl group, respectively.(More)
The products synthesized from a hybrid polyketide synthase/nonribosomal peptide synthetase gene cluster in the genome of Pseudomonas fluorescens Pf-5 were identified using a genomics-guided strategy involving insertional mutagenesis and subsequent metabolite profiling. Five analogs of rhizoxin, a 16-member macrolide with antifungal, phytotoxic, and(More)
Cytotoxicity-guided fractionation of the organic extract from a Fijian Lyngbya majuscula led to the discovery of desmethoxymajusculamide C (DMMC) as the active metabolite. Spectroscopic analysis including 1D and 2D NMR, MS/MS, and chemical degradation and derivatization protocols were used to assign the planar structure and stereoconfiguration of this new(More)
One of the factors of importance in determining the killing of mammalian cells following exposure to a variety of anticancer agents is the proliferative state of the cell population. Generally, proliferating cells are much more sensitive to anticancer agents than are nonproliferating cells. In this review, the cellular aspects of this differential(More)
Three previously unknown pentaketides, (+)-formylanserinone B (3), (-)-epoxyserinone A (4), and (+)-epoxyserinone B (5), along with two known fungal pigments, anserinones A (1) and B (2), were isolated and identified from a deep water (-4380 ft), marine-derived saltwater fungal culture. Two other minor constituents, hydroxymethylanserinone B (6) and(More)
The sponge-derived polyketide macrolides fijianolides A (1) and B (2), isolaulimalide and laulimalide, have taxol-like microtubule-stabilizing activity, and the latter exhibits potent cytotoxicity. Insight on the biogeographical and phenotypic variations of Cacospongia mycofijiensis is presented that will enable a future study of the biosynthetic pathway(More)