Application of an LC–ESI–QTOF–MS method for evaluating clindamycin concentrations in plasma and prostate microdialysate of rats

Clindamycin is used for infections caused by Gram-positive and Gram-negative anaerobic pathogens and Gram-positive aerobes. Propionibacterium acnes is an important opportunistic microorganism of the human skin and is related to prostatitis. An LC–electrospray ionization–quadrupole time-of-flight–MS method was validated for determining clindamycin concentrations in plasma and prostate microdialysate. Clindamycin separation was carried out on a C₁₈ column at 0.5 mL/min. The mobile phase employed gradient elution of formic acid and methanol. A mass spectrometer was operated in positive electrospray ionization mode to monitor ion 425.1784 and 253.1152 for clindamycin and cimetidine (internal standard), respectively. Linearity was obtained at 0.5–10.0 μg/mL (plasma) and 0.05–1.0 μg/mL (microdialysate) with coefficients of determination ≥0.999. The intra- and inter-day precision (coefficient of variation - CV%) values were ≤13.83% and 12.51% for plasma, respectively, and ≤10.90% and 9.35% for microdialysate, respectively. The accuracy was between 90.82% and 108.25% for plasma, and 96.97% and 106.98% for microdialysate. The present method was fully validated and applied to investigate clindamycin concentrations in both plasma and prostate by microdialysis in Wistar rats (80 mg/kg, intravenous). Because the penetration of antibiotics into the prostate may be restricted, this method allows us to investigate the prostate concentrations of clindamycin for the first time.     

A novel synthesis of benzo[c]phenanthridine skeleton and biological evaluation of isoquinoline derivatives.

Benzo[c]phenanthridine skeleton was synthesized from easily available starting N-methyl-o-toluamide 2 and o-methylbenzonitrile 5 in 7 steps. Radical cyclization of styrene 10 afforded 6,11-dimethyl-6,11-dihydro-5H-indeno[1,2-c]isoquinolin-5-one 13. Most 3-arylisoquinolines have displayed strong activities against human tumor cell lines. Especially, indenoisoquinolinone 13 exhibited excellent cytotoxicity (IC50 = 0.002 microgram/ml; HCT 15).     

Microwave-assisted domino access to C2-chain functionalized furans from tertiary propargyl vinyl ethers

Tertiary propargyl vinyl ethers armed with an electron-withdrawing group (amide or ester) at the tertiary propargylic position have been efficiently transformed into trisubstituted C(2)-chain functionalized furans. The metal-free domino transformation involves a microwave-assisted tandem [3,3]-propargyl Claisen rearrangement/5-exo-dig O-cyclization reaction. The manifold can be performed in a one-pot fashion from the primary components (1,2-ketoester/1,2-ketoamide or tertiary propargyl alcohols).     

Hypervalent organochalcogenanes as inhibitors of protein tyrosine phosphatases

A series of organochalcogenanes was synthesized and evaluated as protein tyrosine phosphatases (PTPs) inhibitors. The results indicate that organochalcogenanes inactivate the PTPs in a time- and concentration-dependent fashion, most likely through covalent modification of the active site sulfur-moiety by the chalcogen atom. Consequently, organochalcogenanes represent a new class of mechanism-based probes to modulate the PTP-mediated cellular processes.     

The annealing behavior of hydrogen implanted into Al-1.5 at.% Si alloy

We have studied effects of added elements as well as defects on trap-sites of hydrogen in metals. For the purpose, we observed depth profiles and thermal behaviors of hydrogen implanted into Al-1.5 at.% Si alloy samples in an implantation-temperature range of liquid nitrogen temperature (LNT) to 373 K at different doses. The results were compared with those for pure aluminum samples. It was found that hydrogen is trapped as molecules in grain boundaries of Al/Si.     

Strong optical nonlinearities of self-assembled polymorphic microstructures of phenylethynyl functionalized fluorenones

The polymorphs of a phenylethynyl functionalized fluorenone derivative, and their controlled self-assembly for microstructures with different morphologies have been studied. These polymorphic microcrystals exhibit very distinctive NLO properties, which are highly correlated to their electronic and supramolecular structures.     

Morphology and performance of CoOOH films synthesized via electrochemical oxidation: substrate effects

In the present work, CoOOH films are synthesized from the electrochemical oxidation of α-Co(OH)₂ as precursor. The substrate influences on the material electrochemical properties are studied. The samples are structural and morphologically characterized using techniques of X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques are used for the electrochemical characterization. The films deposited on steel substrate grew in the vertical hexagonal platelet form. Meanwhile, films on Ti plate presented morphology in agglomerated sphere form. After electrochemical oxidation, the film initial morphology is maintained. The films deposited on steel plate have a structure which favors charge storage showing a high specific capacity value (110.92 mA h g^?1) and cyclic stability of 92% after 1000 cycles. Finally, the relaxation time constant value calculated was 5.6 s. This fact is making this material as a possible good candidate for application as electrode material or additive for other materials, in energy storage devices.