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Dopamine (DA) and uric acid (UA) are essential for many physiological processes in the human body. Abnormal levels of DA and UA can lead to multiple diseases, such as Parkinson's disease and gout. In this work, a three-dimensional reduced graphene oxide–MXene (3D rGO-Ti3C2) composite electrode was prepared using a simple one-step hydrothermal reduction process, which could separate the oxidation potentials of DA and UA, enabling the simultaneous detection of DA and UA. The 3D rGO-Ti3C2 electrode exhibited excellent electrocatalytic activity towards both DA and UA. In 0.01 M PBS solution, the linear range of DA was 0.5–500 µM with a sensitivity of 0.74 µA·µM−1·cm−2 and a detection limit of 0.056 µM (S/N = 3), while the linear range of UA was 0.5–60 µM and 80–450 µM, with sensitivity of 2.96 and 0.81 µA·µM−1·cm−2, respectively, and a detection limit of 0.086 µM (S/N = 3). In 10% fetal bovine serum (FBS) solution, the linear range of DA was 0.5–500 µM with a sensitivity of 0.41 µA·µM−1·cm−2 and a detection limit of 0.091 µM (S/N = 3). The linear range of UA was 2–500 µM with a sensitivity of 0.11 µA·µM−1·cm−2 and a detection limit of 0.6 µM (S/N = 3). The modified electrode exhibited advantages such as high sensitivity, a strong anti-interference capability, and good repeatability. Furthermore, the modified electrode was successfully used for DA measurement in vivo. This could present a simple reliable route for neurotransmitter detection in neuroscience. [ABSTRACT FROM AUTHOR]

In this paper, an imine-based porous 3D covalent organic polymer (COP) was synthesized via solvothermal condensation. The structure of the 3D COP was fully characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and powder X-ray diffractometry, thermogravimetric analysis, and Brunauer–Emmer–Teller (BET) nitrogen adsorption. This porous 3D COP was used as a new sorbent for the solid-phase extraction (SPE) of amphenicol drugs, including chloramphenicol (CAP), thiamphenicol (TAP), and florfenicol (FF) in aqueous solution. Factors were investigated for their effects on the SPE efficiency, including the types and volume of eluent, washing speed, pH, and salinity of water. Under the optimized conditions, this method gave a wide linear range (0.1–200 ng/mL) with a high correlation coefficient value (R2 > 0.99), low limits of detection (LODs, 0.01–0.03 ng/mL), and low limits of quantification (LOQs, 0.04–0.10 ng/mL). The recoveries ranged from 83.98% to 110.7% with RSDs ≤ 7.02%. The good enrichment performance for this porous 3D COP might contribute to the hydrophobic and π–π interactions, the size-matching effect, hydrogen bonding, and the good chemical stability of 3D COP. This 3D COP-SPE method provides a promising approach to selectively extract trace amounts of CAP, TAP, and FF in environmental water samples in ng quantities. [ABSTRACT FROM AUTHOR]

Investigation of the chemical constituents from the fruits of Citrus medica L. var. sarcodactylis Swingle has led to the characterization of a new sesquiterpene 1 along with thirty-two known compounds. The structure of 1 was established on the basis of 2D NMR spectroscopic and mass spectrometric analyses, and the known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. In addition, most of the isolated compounds were evaluated for the activity assayed by the in vitro inhibition of superoxide anion generation and elastase release by human neutrophils. The results showed that only 6,7-dimethoxycoumarin (5) exhibited significant inhibition of superoxide anion generation, with IC50 value of 3.8 ± 1.4 μM. [ABSTRACT FROM AUTHOR]

Five new iridoids, salvialosides A–E (compounds 1–5), together with fifty known compounds were isolated from the roots of Salvia digitaloides. The structures of the new compounds were completely elucidated using a combination of 2D NMR techniques (COSY, NOESY, HMQC and HMBC) and HR-ESI-MS analyses. The known compounds were identified by comparison of their spectroscopic and physical data with those reported in the literature. [ABSTRACT FROM AUTHOR]

In the present study, the chemical investigation of the bioactive fractions of the rhizomes of Zingiber officinale has resulted in the identification of twenty-nine compounds including one new compound, O-methyldehydrogingerol (1). Some of the isolates were subjected into the evaluation of their antiplatelet aggregation and vasorelaxing bioactivities. Among the tested compounds, [6]-gingerol (13) and [6]-shogaol (17) exhibited potent anti-platelet aggregation bioactivity. In addition, [10]-gingerol (15) inhibited the Ca2+-dependent contractions in high K+ medium. According to the results in the present research, the bioactivity of ginger could be related to the anti-platelet aggregation and vasorelaxing mechanism. [ABSTRACT FROM AUTHOR]

Molecular latent representations, derived from autoencoders (AEs), have been widely used for drug or material discovery over the past couple of years. In particular, a variety of machine learning methods based on latent representations have shown excellent performance on quantitative structure–activity relationship (QSAR) modeling. However, the sequence feature of them has not been considered in most cases. In addition, data scarcity is still the main obstacle for deep learning strategies, especially for bioactivity datasets. In this study, we propose the convolutional recurrent neural network and transfer learning (CRNNTL) method inspired by the applications of polyphonic sound detection and electrocardiogram classification. Our model takes advantage of both convolutional and recurrent neural networks for feature extraction, as well as the data augmentation method. According to QSAR modeling on 27 datasets, CRNNTL can outperform or compete with state-of-art methods in both drug and material properties. In addition, the performances on one isomers-based dataset indicate that its excellent performance results from the improved ability in global feature extraction when the ability of the local one is maintained. Then, the transfer learning results show that CRNNTL can overcome data scarcity when choosing relative source datasets. Finally, the high versatility of our model is shown by using different latent representations as inputs from other types of AEs. [ABSTRACT FROM AUTHOR]

A highly specific and sensitive proton nuclear magnetic resonance (1H-NMR) method has been developed for the quantification of ephedrine alkaloid derivatives in Ephedra herbal commercial prescriptions. At the region of δ 4.0 to 5.0 ppm in the 1H NMR spectrum, the characteristic signals are separated well from each other, and six analogues in total, methylephedrine (ME), ephedrine (EP), norephedrine (NE), norpseudoephedrine (NP), pseudoephedrine (PE), and methylpseudoephedrine (MP) could be identified. The quantities of these compounds are calculated by the relative ratio of the integral values of the target peak for each compound to the known concentrations of the internal standard anthracene. The present method allows for a rapid and simple quantification of ephedrine alkaloid derivatives in Ephedra-related commercial prescriptions without any preliminary purification steps and standard compounds, and accordingly it can be a powerful tool to verify different Ephedra species. In comparison to conventional chromatographic methods, the advantages of this method include the fact that no standard compounds are required, the quantification can be directly performed on the crude extracts, a better selectivity for various ephedrine alkaloid derivatives, and the fact that a very significant time-gain may be achieved. [ABSTRACT FROM AUTHOR]

Fifty-five compounds were isolated from the fresh stems of Cissus assamica, including 14 benzenoids, 11 triterpenes, nine steroids, five tocopherols, five chlorophylls, four flavonoids, two benzoquinones, two tannins, and three other compounds. Their structures were constructed by 1D and 2D nuclear magnetic resonance (NMR) and mass spectral data, and were also identified by a comparison of their spectral data with those reported in the literature. Among these isolates, 1,2-bis-(5-γ-tocopheryl) ethane (51) was reported for the first time from natural sources. Some purified compounds were examined for their anti-inflammatory and anticancer bioactivities. The results indicated that betulinic acid (16) exhibited strong inhibition of superoxide anion generation with IC50 value of 0.2 ± 0.1 μM, while betulinic acid (16) and pheophytin-a (47) inhibited elastase release with IC50 value of 2.7 ± 0.3 and 5.3 ± 1.0 μM, respectively. In addition, betulinic acid (16) and epi-glut-5(6)-en-ol (18) exhibited potential cytotoxicity to non-small-cell lung carcinoma (NCI-H226) and colon cancer (HCT-116) cell lines with IC50 values in the range of 1.6 to 9.1 μM. [ABSTRACT FROM AUTHOR]