Superhydrophilic molecularly imprinted polymers based on a single cross-linking monomer for the recognition of iridoid glycosides in Di-huang pills

Phytochemistry, synthesis, analytical methods, pharmacological activity, and pharmacokinetics of loganin: A comprehensive review

Iridoid glycosides (IGs) are found in many medicinal and edible plants, such as Gardenia jasminoides, Cistanche tubulosa, Eucommia ulmoides, Rehmanniae Radix, Lonicera japonica, and Cornus officinalis. Loganin, an IG, is one of the main active ingredient of Cornus officinalis Sieb. et Zucc., which approved as a medicinal and edible plant in China. Loganin has been widely concerned due to its extensive pharmacological effects, including anti-diabetic, antiinflammatory, neuroprotective, and anti-tumor activities, etc. Studies have shown that these underlying mechanisms include anti-oxidation, antiinflammation and anti-apoptosis by regulating a variety of signaling pathways, such as STAT3/NF-κB, JAK/STAT3, TLR4/NF-κB, PI3K/Akt, MCP-1/CCR2, and RAGE/Nox4/p65 NF-κB signaling pathways. In order to better understand the research status of loganin and promote its application in human health, this paper systematically summarized the phytochemistry, analysis methods, synthesis, pharmacological properties and related mechanisms, and pharmacokinetics based on the research in the past decades.

Recent advances and applications of molecularly imprinted polymers in solid-phase extraction for real sample analysis

Sample pretreatment is essential for the analysis of complicated real samples due to their complex matrices and low analyte concentrations. Among all sample pretreatment methods, solid-phase extraction is arguably the most frequently used one. However, the majority of available solid-phase extraction adsorbents suffer from limited selectivity. Molecularly imprinted polymers are a type of tailor-made artificial antibodies and receptors with specific recognition sites for target molecules. Using molecularly imprinted polymers instead of conventional adsorbents can greatly improve the selectivity of solid-phase extraction, and therefore molecularly imprinted polymer-based solid-phase extraction has been widely applied to separation, clean up and/or preconcentration of target analytes in various kinds of real samples. In this article, after a brief introduction, the recent developments and applications of molecularly imprinted polymer-based solid-phase extraction for determination of different analytes in complicated real samples during the 2015-2020 are reviewed systematically, including the solid-phase extraction modes, molecularly imprinted adsorbent types and their preparations, and the practical applications of solid-phase extraction to various real samples (environmental, food, biological, and pharmaceutical samples). Finally, the challenges and opportunities of using molecularly imprinted polymer-based solid-phase extraction for real sample analysis are discussed.

Molecularly imprinted polymers prepared from a single cross-linking functional monomer for solid-phase microextraction of estrogens from milk

In this work, a single cross-linking functional monomer, 2,5-divinylterephthalaldehyde, was designed and synthesized to simplify the preparation of molecularly imprinted polymers (MIPs). In the presence of estradiol as a template, MIPs were successfully prepared using 2,5-divinylterephthalaldehyde along with a solvent and initiator. This method reduced most of the complex variables encountered in the traditional synthesis. Characterization of the morphology and structure of the MIPs was performed by scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. Compared with non-imprinted polymers, the MIPs had higher adsorption capacities for five estrogens with imprinting factors above 2.9. The MIPs had high extraction efficiencies, good functional properties, long lifetimes, and good reproducibility, which made them suitable for solid-phase microextraction (SPME). Coupled with ultra-high performance liquid chromatography tandem mass spectrometry, the MIP-based fibers were applied to SPME for the analysis of five estrogens in milk samples. Under the best conditions, the established method had a wide linear range (0.5-10000 ng kg^-1), low limits of detection (0.08-0.26 ng kg^-1) and quantification (0.26-0.87 ng kg^-1), good precision (3.2-8.1%, n = 6), and fiber-to-fiber reproducibility (4.3%-8.8%, n = 3). The MIPs-based fibers can be reused at least 60 times without apparent loss of extraction efficiency. Finally, this method was applied to the determination of target estrogens in milk samples with satisfactory relative recoveries (84.3%-105%, relative standard deviation ≤ 7.8%).