Codeine is a common analgesic drug that is a pro-drug of morphine. It also has a high risk of abuse as a recreational drug because of its extensive distribution as an OTC drug. Therefore, sensitive and selective screening methods for codeine are crucial in forensic analytical chemistry. To date, a commercial analytical kit has not been developed for dedicated codeine determination, and there is a need for an analytical method to quantify codeine in the field. In the present work, potential modulation was combined with electrochemiluminescence (ECL) for sensitive determination of codeine. The potential modulated technique involved applying a signal to electrodes by superimposing an AC potential on the DC potential. When tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)3]2+) was used as an ECL emitter, ECL activity was confirmed for codeine. A detailed investigation of the electrochemical reaction mechanism suggested a characteristic ECL reaction mechanism involving electrochemical oxidation of the opioid framework. Besides the usual ECL reaction derived from the amine framework, selective detection of codeine was possible under the measurement conditions, with clear luminescence observed in an acidic solution. The sensitivity of codeine detection by potential modulated-ECL was one order of magnitude higher than that obtained with the conventional potential sweep method. The proposed method was applied to codeine determination in actual prescription medications and OTC drug samples. Codeine was selectively determined from other compounds in medications and showed good linearity with a low detection limit (150 ng mL−1).
Codeine, is used worldwide and abused as a recreational drug. The authors developed a system to selectively and sensitively detect codeine from over-the-counter medications containing interfering drug components by electrochemiluminescence (ECL) combined with potential modulated technique (PM). The sensitivity for detection of codeine by PM-ECL was more than one order of magnitude larger than that obtained in conventional potential sweep mode. The established technique was applied to codeine determination in over-the-counter drugs and medicines and was not affected by the presence of structurally similar chemicals. The proposed method expected to apply as a sensitive on-site analytical method for a wide range of detection, especially clinical and forensic analysis.
Generating reliable data on functional group compatibility and chemoselectivity is essential for evaluating the practicality of chemical reactions and predicting retrosynthetic routes. In this context, we performed systematic studies using a functional group evaluation kit including 26 kinds of additives to assess the functional group tolerance of carbene-mediated reactions. Our findings revealed that some intermolecular heteroatom–hydrogen insertion reactions proceed faster than intramolecular cyclopropanation reactions. Lewis basic functionalities inhibited rhodium-catalyzed C–H functionalization of indoles. While performing these studies, we observed an unexpected C–H functionalization of a 1-naphthol variant used as an additive.
Reliable data on the compatibility and chemoselectivity of functional groups are essential for assessing the usefulness of chemical reactions. Authors systematically evaluated the functional group tolerance of carbene-mediated reactions as a core project of the Grant-in-Aid for Transformative Research Area A “Digitalization-driven Transformative Organic Synthesis”. In the course of this study, unexpected C-H functionalization of a naphthol derivative used as an additive was observed. Authors believe that collecting dependable information, including negative experimental results, plays a crucial role in developing organic synthesis.
An improvement of the two-photon excitation was achieved using 8-azacoumarin-type caged compounds, which showed large values of the two-photon uncaging action cross-section (δu >0.1 Goeppert–Mayer (GM)). In particular, the 7-hydroxy-6-iodo-8-azacoumarin (8-aza-Ihc)-caged compound showed an excellent uncaging action cross-section value (δu = 1.28 GM). Therefore, 8-azacoumarin-type photolabile protecting groups (PPGs) can be used as two-photon excitation sources.
Photolabile protecting groups (PPGs) have been utilized in many research fields such as organic synthesis and chemical biology because their fast and selective photocleavage proceeds under mild conditions. The authors previously reported the design and synthesis of 8-azacoumarin-type PPGs based on the alkene-to-amide replacement of the 6-bromo-7-hydroxy-coumarin-4-ylmethyl (Bhc) group. The characteristic feature of these PPGs is their aqueous solubility, which is remarkably higher than that of Bhc. The authors found that 8-azacoumarin-type PPGs can also be used as two-photon excitation sources because the photolytic efficiency for two-photon excitation showed preferable physicochemical values for applications in cells and tissues.
Polymeric nanofibers generated via electrospinning offer a promising platform for drug delivery systems. This study examines the application of electrospun polyvinyl alcohol (PVA) nanofibers for controlled lysozyme (LZM) delivery. By using various PVA grades, such as the degree of polymerization/hydrolysis, this study investigates their influence on nanofiber morphology and drug-release characteristics. LZM-loaded PVA monolithic nanofibers having 50% drug content exhibit efficient entrapment, wherein rapid dissolution is achieved within 30 min. The initial burst of LZM from the nanofiber was reduced as the LZM content was lowered. The initial dissolution is greatly influenced by the choice of PVA grade used; fully hydrolyzed PVA nanofibers demonstrate controlled release due to the reduced water solubility of PVA. Furthermore, coaxial electrospinning, which creates core–shell nanofibers with polycaprolactone as a controlled release layer, enables sustained LZM release over an extended period. This study confirms a correlation between PVA characteristics and controlled drug release and provides valuable insights into tailoring nanofiber properties for pharmaceutical applications.
[Highlighted Paper selected
by Editor-in-Chief]
The authors investigated the use of electrospun
polyvinyl alcohol (PVA) nanofibers for the drug delivery of lysozyme (LZM),
focusing on how different PVA grades affect drug release characteristics. PVA
nanofibers with a 50% LZM content achieved efficient encapsulation and quick
release within 30 minutes. Using fully hydrolyzed PVA led to more controlled
release due to its reduced water solubility. Notably, the study highlighted
coaxial electrospinning to create PVA/LZM nanofibers coated with
polycaprolactone, facilitating extended drug release. This approach clarified
the relationship between the characteristics of PVA in nanofibers and drug
release properties, offering promising insights for pharmaceutical nanofibers.
Inhibition of the Thioesterase Activity of Human Fatty Acid Synthase by 1,4- and 9,10-Diones
Released on J-STAGE: September 01, 2014 | Volume 62 Issue 9 Pages 933-936
Herman Odens, Todd Lowther, Steven Kridel, Laura Watts, Lauren Filipponi, Jeffrey Schmitt
Views: 399