Determination of corilagin in rat plasma using a liquid chromatography–electrospray ionization tandem mass spectrometric method

A sensitive and simple liquid chromatography–tandem mass spectrometric (HPLC‐MS/MS) method for the determination of corilagin in rat plasma has been developed. Samples were prepared with protein precipitation method and analyzed with a triple quadrupole tandem mass spectrometer. We employed negative electrospray ionization as the ionization source and the analytes were detected in multiple reaction monitoring mode. Separation was achieved on a C₈ column eluted with mobile phase consisting of methanol–0.1% formic acid in a gradient mode at the flow rate of 0.3 mL/min. The total run time was 7.0 min.This method was proved to have good linearity in the concentration range of 2.5–1000.0 ng/mL. The lower limit of quantification of corilagin was 2.5 ng/mL. The intra‐ and inter‐day relative standard deviationa across three validation runs for four concentration levels were both <9.8%. The relative error was within ±6.0%. This assay offers advantages in terms of expediency and suitability for the analysis of corilagin in rat plasma. The practical utility of this new HPLC‐MS/MS method was confirmed in pilot plasma concentration studies in rats following oral administration. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous Induction of Axial and Planar Chirality in Arene–Chromium Complexes by Molybdenum‐Catalyzed Enantioselective Ring‐Closing Metathesis

The molybdenum‐catalyzed asymmetric ring‐closing metathesis of the various C_s‐symmetric (π‐arene)chromium substrates provides the corresponding bridged planar‐chiral (π‐arene)chromium complexes in excellent yields with up to >99 % ee. With a bulky and unsymmetrical substituent, such as N‐indolyl or 1‐naphthyl, at the 2‐positions of the η⁶‐1,3‐diisopropenylbenzene ligands, both biaryl‐based axial chirality and π‐arene‐based planar chirality are simultaneously induced in the products. The axial chirality is retained even after the removal of the dicarbonylchromium fragment, and the chiral biaryl/heterobiaryl compounds are obtained with complete retention of the enantiopurity.     

Dual‐signal amplification strategy for ultrasensitive chemiluminescence detection of PDGF–BB in capillary electrophoresis

Many efforts have been made toward the achievement of high sensitivity in capillary electrophoresis coupled with chemiluminescence detection (CE‐CL). This work describes a novel dual‐signal amplification strategy for highly specific and ultrasensitive CL detection of human platelet‐derived growth factor–BB (PDGF–BB) using both aptamer and horseradish peroxidase (HRP) modified gold nanoparticles (HRP–AuNPs–aptamer) as nanoprobes in CE. Both AuNPs and HRP in the nanoprobes could amplify the CL signals in the luminol–H₂O₂ CL system, owing to the excellent catalytic behavior of AuNPs and HRP in the CL system. Meanwhile, the high affinity of aptamer modified on the AuNPs allows detection with high specificity. As proof‐of‐concept, the proposed method was employed to quantify the concentration of PDGF–BB from 0.50 to 250 fm with a detection limit of 0.21 fm. The applicability of the assay was further demonstrated in the analysis of PDGF–BB in human serum samples with acceptable accuracy and reliability. The result of this study exhibits distinct advantages, such as high sensitivity, good specificity, simplicity, and very small sample consumption. The good performances of the proposed strategy provide a powerful avenue for ultrasensitive detection of rare proteins in biological sample, showing great promise in biochemical analysis. Copyright © 2015 John Wiley & Sons, Ltd.