Plasma cytokine concentration changes induced by the antitumor agents dipterinyl calcium pentahydrate (DCP) and related calcium pterins
2009, Moheno, Phillip, Pfleiderer, Wolfgang, Fuchs, Dietmar
Analysis of plasma cytokine concentration changes determined that oral dosing with the antitumor agent (1:4 mol:mol) calcium pterin (CaPterin) increased plasma IL-10, decreased plasma IL-6, and decreased plasma IFN-γ concentrations in nude mice with MDA-MB-231 xenograph tumors [Moheno, P., Pfleiderer, W., Dipasquale, A.G., Rheingold, A.L., Fuchs, D., 2008. Cytokine and IDO metabolite changes effected by calcium pterin during inhibition of MDA-MB-231 xenograph tumors in nude mice. Int. J. Pharm. 355, 238–248]. A further analysis, reported here, of plasma cytokine concentration changes in nude mice with the same tumor xenographs treated with dipterinyl calcium pentahydrate (DCP), (1:2 mol:mol) calcium pterin, and CaCl2·2H2O has been carried out. The measured cytokines included: IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IFN-γ, and TNF-α. The major preliminary findings from the analyses of these data are that (1) the overall relative tumor volumes for the treatments correlated significantly with a full study antitumor plasma cytokine pattern (fsAPCP), a composite measure consisting of decreased plasma IL-6 and increased IL-4 concentrations, and (2) DCP induces a significant threshold antitumor response strongly correlated to a derived DCP antitumor plasma cytokine pattern (DCP/APCP) consisting of plasma IL-12, IL-6, and IL-4 concentration changes. This DCP/APCP composite measure identifies plasma IL-12 concentration increases, plasma IL-6 concentration decreases, and plasma IL-4 concentration increases correlated to relative tumor volume decreases caused by DCP dosing. The finding that the novel calcium pterins and CaCl2·2H2O treatments decrease plasma IL-6 concentrations corroborates the previous finding that CaPterin dosing decreases plasma IL-6 concentrations in this mouse/tumor system [Moheno, P., Pfleiderer, W., Dipasquale, A.G., Rheingold, A.L., Fuchs, D., 2008. Cytokine and IDO metabolite changes effected by calcium pterin during inhibition of MDA-MB-231 xenograph tumors in nude mice. Int. J. Pharm. 355, 238–248].
Syntheses and properties of pterin ribonucleosides
2008, Pfadler, Werner, Pfleiderer, Wolfgang
Several pterin derivatives (1-8) have been ribosylated in form of their trimethylsilyl derivatives (9) with 1-bromo-(10) and 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose (11) under the catalysis of HgO/HgBr 2 , BF3 -etherate and trimethylsilyl triflate, respectively. Mixtures of the N-1- (19-25) and N-3-ribofuranosides (12-18) which are difficult to be separated were obtained. Debenzoylation by the Zemplen method led to the free pterin-nucleosides (28-30). A second approach starting from 2-methylthio-4(3H)pteridinones (31-33) gave again mixtures of the N-1-(35-37) and N-3-ribonucleosides (38-40). The 2-methylthio function in 35-37 can easily be substituted by various amines leading after subsequently debenzoylation to the N-2- substituted pterin-ribonucleosides (41-50). The structural assignments were based on comparisons of the UV spectra with the corresponding N-methyl substituted model substances. 1 H-NMR-spectra functioned as additional structural proof.
Triplet-Sensitized Photodeprotection of Oligonucleotides in Solution and on Microarray Chips
2004, Wöll, Dominik, Walbert, Stefan, Stengele, Klaus-Peter, Albert, Tom J., Richmond, Todd, Norton, Jason, Singer, Michael, Green, Roland D., Pfleiderer, Wolfgang, Steiner, Ulrich
Conditions and kinetics of triplet sensitization as a method for increasing the light sensitivity of photolabile protecting groups used for the photolithographic synthesis of oligonucleotide microarrays were quantitatively studied with the photolabile 2-(2-nitrophenyl)propyl protecting group in homogeneous solutions and on glass substrates by using laser flash photolysis, continuous illumination with HPLC analysis, fluorescence dye labelling, and hybridization. In terms of efficiency and avoidance of chemical side reactions, 9H-thioxanthen-9-one was the most-suitable sensitizer. Both in solution and on a glass substrate, the photostationary kinetics were quantitatively modelled and the relevant kinetic parameters determined. While the sensitization kinetics was diffusion-controlled both in solution and on the chip, the photostationary kinetics was essentially of zero order only on the chip because here the triplet-quenching effect of the released photoproduct 2-(2-nitrophenyl)propene was suppressed as a consequence of the inhomogeneous reaction that took place in a narrow diffusion zone above the surface from where the photoproducts could quickly escape. The kinetic simulation allowed quantitative estimate of the density of reactive groups on the surface. It was further demonstrated that, with 9H-thioxanthen-9-one as a sensitizer, high-density oligonucleotide microarrays of high quality can be produced with one-third of the normal exposure time.
Cytokine and IDO metabolite changes effected by calcium pterin during inhibition of MDA-MB-231 xenograph tumors in nude mice
2008-05-01, Moheno, Phillip, Pfleiderer, Wolfgang, DiPasquale, Antonio G., Rheingold, Arnold L., Fuchs, Dietmar
In vivo studies of the effectiveness of various forms of calcium pterin reveal significant antitumor activity associated with (1:4, mol/mol) calcium pterin (CaPterin), (1:2, mol/mol) calcium pterin, dipterinyl calcium pentahydrate (DCP), as well as unexpectedly for a calcium chloride dihydrate solution in nude mice with MDA-MB-231 xenographs. Stepwise regression analysis of nine plasma cytokine and indoleamine 2,3-dioxygenase (IDO) metabolite levels identified four effects correlated to (1:4, mol/mol) calcium pterin administration: (1) decreased IL-6, (2) increased IL-10, (3) decreased IFN-γ, and (4) increased kynurenine. Conclusion: (1:4, mol/mol) CaPterin exerts significant (by Spearman rank order correlation) dose–response antitumor activity in nude mice with MDA-MB-231 xenographs, and sustains both inflammatory and anti-inflammatory changes in the levels of certain plasma factors.
Intramolecular Sensitization of Photocleavage of the Photolabile 2-(2-Nitrophenyl)propoxycarbonyl (NPPOC) Protecting Group: Photoproducts and Photokinetics of the Release of Nucleosides
2008, Wöll, Dominik, Smirnova, Julia, Galetskaya, Marina, Prykota, Tamara, Bühler, Jochen, Stengele, Klaus-Peter, Pfleiderer, Wolfgang, Steiner, Ulrich
Novel photolabile protecting groups based on the 2-(2-nitrophenyl)propoxycarbonyl (NPPOC) group with a covalently linked thioxanthone as an intramolecular triplet sensitizer exhibit significantly enhanced light sensitivity under continuous illumination. Herein we present a detailed study of the photokinetics and photoproducts of nucleosides caged with these new protecting groups. Relative to the parent NPPOC group, the light sensitivity of the new photolabile protecting groups is enhanced by up to a factor of 21 at 366 nm and is still quite high at 405 nm, the wavelength at which the sensitivity of the parent compound is practically zero. A new pathway for deprotection of the NPPOC group proceeding through a nitroso benzylalcohol intermediate has been discovered to complement the main mechanism, which involves elimination. Under standard conditions of lithographic DNA-chip synthesis, some of the new compounds, while maintaining the same chip quality, react ten times faster than the unmodified NPPOC-protected nucleosides.
On the Mechanism of Intramolecular Sensitization of Photocleavage of the 2-(2-Nitrophenyl)propoxycarbonyl (NPPOC) Protecting Group
2007, Wöll, Dominik, Laimgruber, Stefan, Galetskaya, Marina, Smirnova, Julia, Pfleiderer, Wolfgang, Heinz, Björn, Gilch, Peter, Steiner, Ulrich
A spectroscopic study of a variety of covalently linked thioxanthone(TX)-linker-2-(2-nitrophenyl)propoxycarbonyl(NPPOC)-substrate conjugates is presented. Herein, the TX chromophore functions as an intramolecular sensitizer to the NPPOC moiety, a photolabile protecting group used in photolithographic DNA chip synthesis. The rate of electronic energy transfer between TX and NPPOC was quantified by means of stationary fluorescence as well as nanosecond and femtosecond time-resolved laser spectroscopy. A dual mechanism of triplet-triplet energy transfer has been observed comprising a slower mechanism involving the T1(*) state of TX with linker-length-dependent time constants longer than 20 ns and a fast mechanism with linker-length-dependent time constants shorter than 3 ns. Evidence is provided that the latter mechanism is due to energy transfer from the T2(n*) state which is in fast equilibrium with the fluorescent S1(*) state. In the case of direct linkage between the aromatic rings of TX and NPPOC, the spectroscopic properties are indicative of one united chromophore which, however, still shows the typical NPPOC cleavage reaction triggered by intramolecular hydrogen atom transfer to the nitro group.
Synthesis of caged nucleosides with photoremovable protecting groups linked to intramolecular antennae
2005, Smirnova, Julia, Wöll, Dominik, Pfleiderer, Wolfgang, Steiner, Ulrich
Based on the [2-(2-nitrophenyl)propoxy]carbonyl (nppoc) group, six new photolabile protecting groups (2, 8, 9b, 16b, 25b, and 26), each covalently linked to a 9H-thioxanthen-9-one (Tx) unit functioning as an intramolecular triplet sensitizer, were synthesized. Linkers were introduced between the Me group or the aromatic ring of nppoc and the 2-position of Tx by means of classical organic synthesis combined with Pd catalyzed CC coupling reactions. The new photolabile protecting groups to be used in light-directed synthesis of DNA chips were attached to the 5-O-atom of thymidine via a carbonate linkage, giving rise to the caged nucleosides 7, 11, 13, 19, 20, and 30.