- Minutissamides E-L, antiproliferative cyclic lipodecapeptides from the cultured freshwater cyanobacterium cf. Anabaena sp.
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The extract of UIC 10035, a strain obtained from a sample collected near the town of Homestead, South Florida, showed antiproliferative activity against MDA-MB-435 cells. Bioassay-guided fractionation led to the isolation of a series of cyclic lipodecapeptides, named minutissamides E-L (1-8). The planar structures were determined by analysis of HRESIMS, tandem MS, and 1D and 2D NMR data, and the stereoconfigurations were assigned by LC-MS analysis of the Marfey's derivatives after acid hydrolysis. Minutissamides E-L (1-8) exhibited antiproliferative activity against MDA-MB-435 cells with IC50 values ranging between 1 and 10 μM. The structures of minutissamides E-L (1-8) were closely related with those of the previously reported lipopeptides, puwainaphycins A-E and minutissamides A-D, characterized by the presence of a lipophilic β-amino acid and three non-standard amino acids NMeAsn, OMeThr and Dhb (α,β-dehydro-α-aminobutyric acid). The strain UIC 10035 was designated as cf. Anabaena sp. on the basis of morphological and 16S rRNA gene sequence analyses.
- Kang, Hahk-Soo,Sturdy, Megan,Krunic, Aleksej,Kim, Hyunjung,Shen, Qi,Swanson, Steven M.,Orjala, Jimmy
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- Homophymine A, an anti-HIV cyclodepsipeptide from the sponge Homophymia sp.
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(Chemical Equation Presented) A new anti-HIV cyclodepsipeptide, homophymine A, was isolated from a New Caledonian collection of the marine sponge Homophymia sp. The structure of homophymine A was determined by interpretation of spectroscopic data, acid hydrolysis, and LC-MS analysis. Homophymine A contains 11 amino acid residues and an amide-linked 3-hydroxy-2,4,6- trimethyloctanoic acid moiety. Along with four D-, two L-, and one N-methyl amino acids, it also contains four unusual amino acid residues: (2S,3S,4R)-3,4-diMe-Gln, (2R,3R,4S)-4-amino-2,3-dihydroxy-1,7-heptandioic acid, L-ThrOMe, and (2R,3R,4R)-2-amino-3-hydroxy-4,5-dimethylhexanoic acid. In a cell-based XTT assay, homophymine A exhibited cytoprotective activity against HIV-1 infection with a IC50 of 75 nM.
- Zampella, Angela,Sepe, Valentina,Luciano, Paolo,Bellotta, Filomena,Monti, Maria Chiara,D'Auria, Maria Valeria,Jepsen, Trine,Petek, Sylvain,Adeline, Marie-Therese,Laprevote, Olivier,Aubertin, Anne-Marie,Debitus, Cecile,Poupat, Christiane,Ahond, Alain
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- Syntheses of isotopically labelled L-?±-amino acids with an asymmetric centre at C-3
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Approaches are described to the synthesis of a series of isotopically labelled L-a-amino acids each with an asymmetric centre at C-3, including isoleucine, allo-isoleucine, threonine and allo-threonine. The methods may be simply adapted for the selective incorporation of an isotopic label at each site of L-valine including the selective labelling of either diastereotopic methyl group with carbon-13 and/or deuterium and labelling of the amine with nitrogen-15. ? The Royal Society of Chemistry 2000.
- Harding, John R.,Hughes, Rachael A.,Kelly, Nicholas M.,Sutherland, Andrew,Willis, Christine L.
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p. 3406 - 3416
(2007/10/03)
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- Enantioselective syntheses of α-amino-β-hydroxy acids, [15N]-L-allothreonine and [15N]-L-threonine
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The enantioselective synthesis of [15N]-L-allothreonine from ethyl (S)-lactate via methyl (S)-3-methoxymethoxy-2-oxobutanoate 15 is described. The stereogenic centre at C-2 was established by a one-pot, dual enzyme catalysed hydrolysis of the ester (by a lipase) and reductive amination of the ketone of 15 (with leucine dehydrogenase) to give, after deprotection, [15N]-(2S,3S)-2-amino-3-hydroxybutanoic acid as a single diastereomer in 93% yield. [15N]-L-Threonine was prepared by an analogous strategy from methyl (R)-lactate using phenylalanine dehydrogenase in the reductive amination step. This approach may be simply adapted for the incorporation of deuterium and carbon-13.
- Sutherland, Andrew,Willis, Christine L.
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p. 1837 - 1840
(2007/10/03)
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- General Method for the Asymmetric Synthesis of anti-Diastereoisomers of β-Substituted L-2-Aminobutanoic Acids via Chiral Nickel(II) Schiff's Base Complexes of Dehydroaminobutanoic Acid. X-Ray Crystal and Molecular Structure of the Nickel(II) Complex of the Schiff's Base from <(Benzyl...
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An efficient approach to the asymmmetric synthesis of (L)-allo-isomers of β-substituted α-aminobutanoic acid is described.The chiral NiII complex of a Schiff's base derived from (S)-o-benzophenone (BBP) and glycine was treated with acetaldehyde in MeOH.The addition proceeds with high diastereoselectivity to give, if catalysed by MeONa, the corresponding complex of (R)-threonine, and, if catalysed by Et3N, the corresponding complex of (S)-allo-threonine.The (R)-threonine complex was converted into the chiral NiII complex of dehydroaminobutanoic acid, and a X-ray diffraction structural study of its major isomer showed that the dehydroaminobutanoic acid moiety was in the E-configuration.The complex, in turn, entered into Michael addition reactions with nucleophiles, including MeOH, EtOH, PhSH, and PhCH2SH.The reaction proceeded with high diastereoselectivity, producing predominantly complexes of the allo-threonine derivatives (d.e. > 90percent).Diastereoisomerically and enantiomerically pure α-amino acids were obtained after chromatographic purification, decomposition of the complexes, and recovery of the initial chiral auxiliary, BBP.The thiol addition reaction is accompanied by a side reaction leading to the formation of sizeable amounts of the vinylglycine complex.An approach to the synthesis of optically active vinylglycine starting with racemic methionine is described.
- Belokon', Yuri N.,Sagyan, Ashot S.,Djamgaryan, Silva A.,Bakhmutov, Vladimir I.,Vitt, Sergei V.,et al.
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p. 2301 - 2310
(2007/10/02)
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- Peptide substituted penicillins
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A compound of formula I or a physiologically acceptable salt thereof STR1 wherein X represents sulphur or methylene, R1 represents hydrogen, amino or an acylated or carbamylated amino group, R2 represents hydrogen or an alkyl group and R3 represents an alkoxy group.
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- Diamine compounds
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Compounds of the general formula I wherein R1 represents an optionally substituted C6-10 aryl group, or R1 represents an optionally substituted 5- or 6--membered heterocyclic moiety;, X represents a single bond, -CH2-, -OCH2/su
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