ABSTRACT
Cubozoan nematocyst venoms contain known cytolytic and hemolytic proteins, but small molecule components have not been previously reported from cubozoan venom. We screened nematocyst extracts of Alatina alata and Chironex yamaguchii by LC-MS for the presence of small molecule metabolites. Three isomeric compounds, cnidarins 4A (1), 4B (2), and 4C (3), were isolated from venom extracts and characterized by NMR and MS, which revealed their planar structure as cyclic γ-linked tetraglutamic acids. The full configurational assignments were established by syntheses of all six possible stereoisomers, comparison of spectral data and optical rotations, and stereochemical analysis of derivatized degradation products. Compounds 1-3 were subsequently detected by LC-MS in tissues of eight other cnidarian species. The most abundant of these compounds, cnidarin 4A (1), showed no mammalian cell toxicity or hemolytic activity, which may suggest a role for these cyclic tetraglutamates in nematocyst discharge.
Subject(s)
Cubozoa/chemistry , Glutamic Acid/biosynthesis , Glutamic Acid/isolation & purification , Animals , Aquatic Organisms/chemistry , Cell Death/drug effects , Chromatography, High Pressure Liquid , Chromatography, Reverse-Phase , Cnidarian Venoms/chemistry , Cnidarian Venoms/toxicity , Glutamic Acid/chemistry , HEK293 Cells , Hemolysis/drug effects , Humans , Proton Magnetic Resonance Spectroscopy , Tissue DistributionABSTRACT
A preparation of 2-formyl-2-cyclohexenone in nearly quantitative yield and purity of approximately 95% is described. It is scalable and has been extended to the synthesis of the 5- and 7-membered ring homologs with comparable yields. Conditions have also been developed for the successful conjugate addition of dimethylmalonate to 2-formyl-2-cyclohexenone, in good and scalable yield (60%). This result has been extended to 5 other nucleophile classes, and the dimethylmalonate conjugate addition has been demonstrated with 2-formyl-2-cyclopentenone and 2-formyl-2-cycloheptenone.
ABSTRACT
Attachment of targeted ligands to nonviral DNA or RNA delivery systems is a promising strategy that seeks to overcome the poor target selectivity generally observed in systemic delivery applications. Several methods have been developed for the conjugation of ligands to lipids or polymers, however, direct conjugation of ligands onto lipid- or polymer-nucleic acid complexes is not as straightforward. Here, we examine an oximation approach to directly label a lipoplex formulation. Specifically, we report the synthesis of a cationic diketo lipid DMDK, and its use as a convenient ligation tool for attachment of aminooxy-functionalized reagents after its complexation with DNA. We demonstrate the feasibility of direct lipoplex labeling by attaching an aminooxy-functionalized fluorescent probe onto pre-formed plasmid DNA-DMDK lipoplexes (luciferase, GFP). The results reveal that DMDK protects DNA from degradation on exposure to either DNase or human cerebral spinal fluid, and that simple mixing of DMDK lipoplexes with the aminooxy probe labels the complexes without sacrificing transfection efficiency. The biocompatibility and selectivity of this method, as well as the ease of bioconjugation, make this labeling approach ideal for biological applications.
Subject(s)
DNA/chemistry , Drug Carriers/chemical synthesis , Fatty Acids, Unsaturated/chemical synthesis , Lipids/chemistry , Oximes/chemistry , Animals , CHO Cells , Cerebrospinal Fluid/chemistry , Cerebrospinal Fluid/enzymology , Cricetinae , Cricetulus , Deoxyribonucleases/chemistry , Drug Carriers/chemistry , Drug Carriers/pharmacology , Fatty Acids, Unsaturated/chemistry , Fluorescent Dyes/chemistry , Green Fluorescent Proteins/biosynthesis , Green Fluorescent Proteins/chemistry , Green Fluorescent Proteins/genetics , Humans , Ligands , Luciferases/chemistry , Molecular Structure , Oximes/chemical synthesis , Oximes/pharmacology , Stereoisomerism , Transfection/methodsABSTRACT
The total synthesis of racemic terpestacin and 11-epi-terpestacin using the allene ether Nazarov reaction as the key step is described. All stereochemistry is derived from the stereogenic carbon atom that is formed during the Nazarov reaction.
Subject(s)
Bridged Bicyclo Compounds/chemical synthesis , Bridged Bicyclo Compounds/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Spectrometry, Mass, Electrospray Ionization , Spectrophotometry, Infrared , StereoisomerismABSTRACT
[reaction: see text] The alpha-hydroxycyclopentenone core structure of terpestacin has been prepared in a model system through an allene ether Nazarov cyclization of an alkylidene-gamma-butyrolactone followed by regio- and stereoselective alkylation reactions. The stereochemistry at C15 (terpestacin numbering) has been used to control stereochemistry at C1 and at C23. The use of E-alkylidene-gamma-butyrolactones extends the scope of the cationic cyclopentannelation reaction.
Subject(s)
Cyclopentanes/chemistry , Alkylation , Bridged Bicyclo Compounds/chemistry , Molecular Structure , StereoisomerismABSTRACT
We present a short synthesis of 1-(2-indenyl)-2-(3-indenyl)ethane (5) and a method for its conversion to the ansa-metallocene [ethylene(eta5-inden-1-yl)(eta5-inden-2-yl)]titanium dichloride (13). The synthetic strategy applied to prepare bisindene 5 relies on the efficient alkylation of 2-(phenylsulfonyl)indane followed by HMPA-assisted E1cB-elimination of phenylsulfinate. This tandem sequence circumvents the predisposition of indene to undergo C(1)-alkylation and enables access to C(2)-substituted indenes. The key step in the synthesis of the title ansa-titanocene (4) features a previously unreported equilibration step to generate the bis(indenide anion) of 5. Complexation with TiCl4.(THF)2 followed by hydrogenation of the product metallocene furnishes ansa-titanocene 4.
ABSTRACT
Our previous screen of flavones and related heterocycles for the ability to activate the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel indicated that UCCF-029, a 7,8-benzoflavone, was a potent activator. In the present study, we describe the synthesis and evaluation, using cell-based assays, of a series of benzoflavone analogues to examine structure-activity relationships and to identify compounds having greater potency for activation of both wild type CFTR and a mutant CFTR (G551D-CFTR) that causes cystic fibrosis in some human subjects. Using UCCF-029 as a structural guide, a panel of 77 flavonoid analogues was prepared. Analysis of the panel in FRT cells indicated that benzannulation of the flavone A-ring at the 7,8-position greatly improved compound activity and potency for several flavonoids. Incorporation of a B-ring pyridyl nitrogen either at the 3- or 4-position also elevated CFTR activity, but the influence of this structural modification was not as uniform as the influence of benzannulation. The most potent new analogue, UCCF-339, activated wild-type CFTR with a K(d) of 1.7 microM, which is more active than the previous most potent flavonoid activator of CFTR, apigenin. Several compounds in the benzoflavone panel also activated G551D-CFTR, but none were as active as apigenin. Pharmacophore modeling suggests a common binding mode for the flavones and other known CFTR activators at one of the nucleotide-binding sites, allowing for the rational development of more potent flavone analogues.
