Design and synthesis of novel xyloketal derivatives and their protective activities against H2O2-induced HUVEC injury.

In this work, we designed and synthesized a series of amide derivatives (1-13), benzoxazine derivatives (16-28) and amino derivatives (29-30) from xyloketal B. All 28 new derivatives and seven known compounds (14, 15, 31-35) were evaluated for their protection against H2O2-induced HUVEC injury. 23 and 24 exhibited more potential protective activities than other derivatives; and the EC50 values of them and the leading compound 31 (xyloketal B) were 5.10, 3.59 and 15.97 µM, respectively. Meanwhile, a comparative molecular similarity indices analysis (CoMSIA) was constructed to explain the structural activity relationship of these xyloketal derivatives. This 3D QSAR model from CoMSIA suggested that the derived model exhibited good predictive ability in the external test-set validation. Derivative 24 fit well with the COMSIA map, therefore it possessed the highest activity of all compounds. Compounds 23, 24 and 31 (xyloketal B) were further to examine in the JC-1 mitochondrial membrane potential (MMP) assay of HUVECs using flow cytometry (FCM). The result indicated that 23 and 24 significantly inhibited H2O2-induced decrease of the cell mitochondrial membrane potential (ΔΨm) at 25 µM. Collectively, the protective effects of xyloketals on H2O2-induced endothelial cells may be generated from oxidation action by restraining ROS and reducing the MMP.

Isolation of fucoxanthin from edible brown algae by microwave-assisted extraction coupled with high-speed countercurrent chromatography.

A rapid and efficient method for the separation and purification of fucoxanthin from edible brown algae by microwave-assisted extraction coupled with high-speed countercurrent chromatography was developed. The algae were first extracted using microwave-assisted extraction, then the dried extract was dissolved and directly introduced into the high-speed countercurrent chromatography system with a two-phase solvent system consisting of hexane-ethyl acetate-ethanol-water (5:5:6:4, v/v/v/v). The isolation was done in less than 75 min, and a total of 0.83 mg, 1.09 mg, and 0.20 mg fucoxanthin were obtained from 25.0 g fresh Laminaria japonica Aresch, 1.5 g dry Undaria pinnatifida (Harv) Sur, and 15.0 g dry Sargassum fusiforme (Harv) Setch, respectively. The purity of fucoxanthin determined by HPLC was over 90% and its structure was further identified by LC-ESI-MS and (1) H-NMR.

Evaluation of microwave-assisted extraction for aristolochic acid from Aristolochiae Fructus by chromatographic analysis coupled with nephrotoxicity studies.

In this paper, a microwave-assisted extraction (MAE) method was established for aristolochic acid-I from Aristolochiae Fructus, and the advantage of MAE was evaluated by chromatographic analysis coupled with nephrotoxicity studies. The experimental parameters of MAE for aristolochic acid-I in Aristolochiae Fructus were investigated and MAE was compared with Soxhlet extraction and ultrasound-assisted extraction in terms of extraction yields and extraction conditions. Under the optimum conditions, MAE could provide higher extraction yields of aristolochic acid-I (1.10 mg/g) than ultrasound-assisted extraction (0.82 mg/g) and Soxhlet extraction (0.95 mg/g), in addition to using less solvent and having a shorter extraction time. Furthermore, the nephrotoxicities of the extracts of Aristolochiae Fructus from different extraction procedures were investigated in Sprague-Dawley rats. The results of nephrotoxicity studies of, for example, general conditions, biochemistry parameters and histopathology examination showed no significantly differences in the nephrotoxicity levels of the extracts from MAE and that from Soxhlet extraction. These results indicated that MAE technique is a simple, rapid and effective extraction method, and the microwave irradiation during MAE procedure did not have any influence on the nephrotoxicity of Aristolochiae Fructus compared with Soxhlet extraction.

Rapid analysis of ractopamine in pig tissues by dummy-template imprinted solid-phase extraction coupling with surface-enhanced Raman spectroscopy.

Ritodrine has similar skeleton structure to ractopamine and it was selected as the dummy-template molecule to synthesize the molecular imprinted polymers (MIPs). The MIPs exhibited better selectivity to ractopamine than to the dummy-template molecule: the imprint factor for ractopamine was 8.9, while 7.6 for ritodrine. The MIPs were used as sorbents in solid-phase extraction for selective enrichment of ractopamine, and some key parameters were optimized. After that, a rapid surface-enhanced Raman spectroscopy method was developed for analysis of ractopamine and isoxuprine in pig tissue samples. Under the optimal conditions, good linearity was achieved in the range of 20.0-200.0 µg/L for ractopamine and isoxsuprine at 842 cm(-1) and 993 cm(-1), respectively. The limits of detection were 3.1-4.3 µg/L, which were lower than the maximum allowed by U. S. Food and Drug Administration. The recoveries of ractopamine and isoxsuprine were 72.4-79.7% and 71.0-78.2% for the spiked pork and pig liver, respectively, while the relative standard deviations ranging from 7.4% to 13.0%. The results suggest that the proposed method is sensitive and selective, and it has good potential on the quantitative analysis of trace amounts of ß-agonists in complex samples.

Optic properties of bile liquid crystals in human body.

AIM:To further study the properties of bile liquid crystals, and probe into the relationship between bile liquid crystals and gallbladder stone formation, and provide evidence for the prevention and treatment of cholecystolithiasis.METHODS:The optic properties of bile liquid crystals in human body were determined by the method of crystal optics under polarizing microscope with plane polarized light and perpendicular polarized light.RESULTS:Under a polarizing microscope with plane polarized light, bile liquid crystals scattered in bile appeared round, oval or irregularly round. The color of bile liquid crystals was a little lighter than that of the bile around. When the stage was turned round, the color of bile liquid crystals or the darkness and lightness of the color did not change obviously. On the border between bile liquid crystals and the bile around, brighter Becke-Line could be observed. When the microscope tube is lifted, Becke-Line moved inward, and when lowered, Becke-Line moved outward. Under a perpendicular polarized light, bile liquid crystals showd some special interference patterns, called Malta cross. When the stage was turning round at an angle of 360(o), the Malta cross showed four times of extinction. In the vibrating direction of 45(o) angle of relative to upper and lower polarizing plate, gypsum test-board with optical path difference of 530nm was inserted, the first and the third quadrants of Malta cross appeared to be blue, and the second and the fourth quadrants appeared orange. When mica test-board with optical path difference of 147nm was inserted, the first and the third quadrants of Malta cross appeared yellow, and the second and the fourth quadrants appeared dark grey.CONCLUSION:The bile liquid crystals were distributed in bile in the form of global grains. Their polychroism and absorption were slight, but the edge and Becke-Line were very clear. Its refractive index was larger than that of the bile. These liquid crystals were uniaxial positive crystals. The interference colors were the first order grey-white. The double refractive index of the liquid crystals was n = 0.011-0.015.