Synthesis of 8-substituted 5-deazaflavins

To obtain 5-deazaflavins exhibiting red-shifted light absorption spectra, a number of C(8) substituted 5-deazaisoalloxazines were synthesized. This was accomplished a) by the oxidative cyclization of 5,5′-arylmethylenebis(6-methylaminouracil) derivatives and b) by the cyclization of N-methylanilinouracil derivatives with a one-carbon reagent. The latter method led to the formation of impure products. Condensation and oxidation reactions with the π-electron deficient C(8) methyl group in 5-deazalumiflavin did not occur. Introduction of substituents at the C(8) position caused a bathochromic shift that varied between 10 and 40 nm.     

Über die Synthese der Pilocarpus-Alkaloide Isopilosin und Pilocarpin,sowie die absolute Konfiguration des (+)-Isopilosins

A novel synthesis for rac-pilosinine ( 6 rac) and transformation of (+)-pilosinine ( 6 ) into the pilocarpus alkaloids (+)-isopilosine ( 9 ) and (+)-pilocarpine ( 18 ) are described. By correlation via 5 with 18 the absolute configuration of (+)-isopilosine ( 9 ) is established.     

Synthesis of water soluble 8-substituted 5-deazaflavins

By oxidative cyclization of 5,5′-arylmethylenebis(6-methylaminouracil) derivatives with diethyl azodicarb-oxylate a number of 5-deazaisoalloxazines were synthesized having at the C(8) position a substituent that causes a bathochromic shift varying between 20 and 130 nm, depending on the substituent. To increase the solubility in aqueous media 8-substituted 5-deazaflavins were prepared having a carboxymethyl group at the N(3) position. The carboxymethyl group was introduced prior to the oxidative cyclization.     

High-performance liquid chromatographic quantitation of rhodamines 123 and 110 from tissues and cultured cells

Rhodamine 123 is a fluorescent vital dye which has potential for therapeutic use in cancer treatment. The dye concentrates in mitochondria of normal and neoplastic cells but accumulates in and is toxic to neoplastic cells. When dye-treated cells are irradiated with blue laser light at 514 nm, mitochondrial injury or cell death results. Rhodamine concentration in cultured cells and tumor tissue was quantitated to correlate cell or tumor death with drug dose. A reversed-phase separation of rhodamine 123 was accomplished using a gradient of 0.05 M phosphate buffer pH 2.85 (mobile phase A) and acetonitrile (mobile phase B), 10-80% B in 15 min with a DuPont Golden Series C8 column. Effluent was monitored with a fluorescence detector at 295 nm excitation and 520 nm emission. Stock rhodamine 123 contained approximately 6-8% of rhodamine 110, the parent compound, which eluted at 9.8 min whereas rhodamine 123 eluted at 11.7 min. Structural verification of both compounds by field desorption mass spectrometry was performed. This is the first report of the chemical separation and quantitation of rhodamine 123 from cultured tumor cells or tumor tissue.     

Abkömmlinge der 3-Chinolincarbonsäure mit Sauerstoffsubstitution in Stellung 4, 5 and 8: Synthese,Reaktionen, NMR.-Studien

Derivatives of 3-Quinolinecarboxylic Acid with Oxygen Substitution in Positions 4, 5 and 8: Synthesis, Reactions, NMR. Studies Starting from either 1, 4-dibenzyloxybenzene (7) or 2, 5-dimethoxyaniline ( 16 ), synthetic routes have been developed to benzenoid and quinoid derivatives of 4-oxo-1, 4-dihydro-3-quinolinecarboxylic acid with O-bearing substituents in the positions 5 and 8 (compounds 12 - 15 , 19 , 20 , 23 , and 24 ). With the 1-ethyl-4, 5, 8 trioxo acid 14 as a dienophile, a series of linear tricyclic diene adducts ( 29 - 32 ) has been prepared, the structures of which were further modified by aromatization, reduction or dehydrogenation (compounds 33 - 40 ). A series of benzenoid and quinoid compounds with an additional substituent in position 6 or 7 (Table 1) has been derived mainly from the quinone 14 , primarily by addition of nucleophiles and eventually subsequent steps, and by aromatic electrophilic substitution of the 1-ethyl-5, 8-dimethoxy acid 23 . The substitution pattern of some of these compounds has been elucidated by detailed ¹³C-NMR. studies (Table 2) and/or nuclear Overhauser-effect studies (Table 3). Correlations, based essentially on chemical arguments, allowed to define the structures of most of the residual new compounds (Table 4).     

SPECTROSCOPY AND PHOTOCHEMISTRY OF 8-SUBSTITUTED 5-DEAZAFLAVINS

Abstract— Absorption, fluorescence and phosphorescence spectra as well as fluorescence and phosphorescence quantum yields of 8-X-5-deazaflavins (X = C1, NO₂, p -NO₂-C₆H₄, N(CH₃)₂, NH₂, p -NH₂-C₆H₄, p -N(CH₃)₂-C₆H₄-N=N) were determined. It was found that all these data are highly influenced by the substituent at position 8 of the 5-deazaisoalloxazine skeleton. Also the photoreduction of 8-X-5-deazaflavins in the presence of electron donors was studied. It was established that the photoreduction leads to the formation of a 5,5'-dimer and/or a 6,7-dihydro compound. Reduction of the C(6)-C(7) bond is promoted by strong electron-donating substituents and bulky electron donors. 5-Deazaftavins with a reducible substituent at position 8 exhibit reduction of the substituent prior to the reduction of the 5-deazaisoalloxazine skeleton.     

Selection and rapid purification of murine antibody fragments that bind a transition-state analog by phage display

Functional antibody fragments may be displayed on the surface of filamentous bacteriophage by introducing variable region genes into the viral genome at a gene encoding a viral coat protein. “Phage display” enables the isolation of antibody genes from large libraries according to the binding specificities they encode. We have constructed a new phage-display vector encoding a polyhistidine tag that has been used for rapid purification of soluble antibody fragments. An antibody library derived from immunized mice was cloned into this vector. This library was panned against the transition state analog RT3, and a high proportion of binders isolated after two rounds of panning. PCR analysis revealed that there were 24 different pattern groups. Sequencing of 15 clones within the major pattern group revealed 10 related clones with a range of point mutations. Thus, phage display can provide a large diverse repertoire of candidate catalytic antibodies based on TSA selection and screening.     

Synthese von 2,4-Diamino-thieno[2,3-d]pyrimidin-Derivaten

Synthesis of 2,4-Diamino-thieno[2,3-d]pyrimidines Condensation of 2-aminothiophene-3-carbonitrile ( 4 ) with guanidine or sequential addition of CS₂ and NH₃ to 4 provides 2,4-diaminothieno[2,3-d]pyrimidine ( 7 ). This compound yields, after sequential addition of sec-BuLi and either [3-(trifluoromethyl)benzene]sulfenyl chloride ( 8 ) or the corresponding disulfide 9 , followed by acidic work up, 2,4-diamino-6-{[3-(trifluoromethyl)phenyl]thio}thieno[2,3-d]pyrimidine ( 10 ). In another approach, 2-amino-5-{[3-(trifluoromethyl)phenyl]thio}thiophene-3-carbonitrile ( 11 ) obtained from 4 and 8 is transformed to 10 by condensation with guanidine. Corresponding to the second route, 2,4-diamino-6-[(naphth-2-yl)thio]thieno-[2,3-d]pyrimidine ( 16 ) is synthesized. Oxidation of 10 with m-chloroperbenzoic acid gives 2,4-diamino-6-{[3-(tri-fluoromethyl)phenyl]sulfinyl}thieno[2,3-d]pyrimidine ( 13 ).