Synthesis of C-2 Unsubstituted Furanonaphthoquinones

Four C-2 unsubstituted naphtho[2,3-b]furan-4,9-quinones were prepared via the corresponding phthalides obtained by directed ortho-metalation-based route.     

New Nitrogen Derivatives of Podophyllotoxin and a Novel Access to Dehydroanhydropicropodophyllin

The new compounds podophyllotoxone oxime (3) and epipodophyllotoxin azide (5) were prepared. The known dehydroanhydropicropodophyllin (6) was unexpectedly obtained from podophyllotoxin (1) by treatment with TMSCl/NaI/MeCN.     

Rational Perturbation of the Fluorescence Quantum Yield in Emission‐Tunable and Predictable Fluorophores (Seoul‐Fluors) by a Facile Synthetic Method Involving C?H Activation

Fluorescence imaging enables the uniquely sensitive observation of functional‐ and molecular‐recognition events in living cells. However, only a limited range of biological processes have been subjected to imaging because of the lack of a design strategy and difficulties in the synthesis of biosensors. Herein, we report a facile synthesis of emission‐tunable and predictable Seoul‐Fluors, 9‐aryl‐1,2‐dihydrolopyrrolo[3,4‐b]indolizin‐3‐ones, with various R¹ and R² substituents by coinage‐metal‐catalyzed intramolecular 1,3‐dipolar cycloaddition and subsequent palladium‐mediated C H activation. We also showed that the quantum yields of Seoul‐Fluors are controlled by the electronic nature of the substituents, which influences the extent of photoinduced electron transfer. On the basis of this understanding, we demonstrated our design strategy by the development of a Seoul‐Fluor‐based chemosensor 20 for reactive oxygen species that was not accessible by a previous synthetic route.     

Radioactive 129I in surface water of the Celtic Sea

Relatively large amounts of radioactive iodine ¹²⁹I (T _1/2  = 15.7 Ma) have been documented in seawater such as the English Channel, the Irish Sea and the North Sea. Data on the concentration of the iodine isotopes in waters of the Celtic Sea are missing. Aiming to provide first ¹²⁹I data in the Celtic Sea and compare them with levels in the other close-by seawater bodies, surface seawater samples were analyzed for the determination of ¹²⁷I and ¹²⁹I concentrations. The results revealed a high level of ¹²⁹I in these waters and suggest strong influence by liquid discharges from La Hague and Sellafield reprocessing facilities. ¹²⁷I concentrations are rather constant while the ¹²⁹I/¹²⁷I ratio reaches up to 2.8 × 10^?8 (ranging from 10^?10 to 10^?8), which is 2–4 orders of magnitude higher than pre-nuclear era natural level. Transport of ¹²⁹I to the Celtic Sea is difficult to depict accurately since available data are sparse. Most likely, however, that discharges originated from La Hague may have more influence on the Celtic Sea ¹²⁹I concentrations than the Sellafield. Comprehensive surface water and depth profiles ¹²⁹I data will be needed in the future for assessment of environmental impact in the region.     

Direct determination of antibacterial norfloxacin in urine by isopotential fluorimetry

A novel and simple method is presented for the determination of norfloxacin in human urine by matrix isopotential synchronous fluorescence spectrometry (MISF). This method is useful for the determination of compounds in samples with unknown background fluorescence, such as norfloxacin in urine, without the need for tedious sample pre-treatment. The method was performed in ethanol-water medium (10% v/v), at an apparent pH of 4.8 provided by adding sodium acetate-acetic acid buffer solution. In the determination of norfloxacin in urine the fluorescent intensity varied linearly with its concentration from 20 to 200 ng/mL. An exhaustive statistical analysis has been developed to all calibration graphs, this treatment includes robust regression such as least median of squares, which also detects outliers and leverage points. The overall least-squares regression has been applied to find the more exact straight line that fits the experimental data. The error propagation has been considered to calculate the detection limit and the repeatability of the method. The method shows very low detection limits with acceptable recoveries and precisions. The applicability of the proposed method was illustrated in the determination of norfloxacin in human urine sample without sample pre-treatment.     

Synthesis and Evaluation of GdIII‐Based Magnetic Resonance Contrast Agents for Molecular Imaging of Prostate‐Specific Membrane Antigen

Magnetic resonance (MR) imaging is advantageous because it concurrently provides anatomic, functional, and molecular information. MR molecular imaging can combine the high spatial resolution of this established clinical modality with molecular profiling in vivo. However, as a result of the intrinsically low sensitivity of MR imaging, high local concentrations of biological targets are required to generate discernable MR contrast. We hypothesize that the prostate‐specific membrane antigen (PSMA), an attractive target for imaging and therapy of prostate cancer, could serve as a suitable biomarker for MR‐based molecular imaging. We have synthesized three new high‐affinity, low‐molecular‐weight Gd^III‐based PSMA‐targeted contrast agents containing one to three Gd^III chelates per molecule. We evaluated the relaxometric properties of these agents in solution, in prostate cancer cells, and in an in vivo experimental model to demonstrate the feasibility of PSMA‐based MR molecular imaging.