Duolong Di

Adsorption Characteristics of (−)-Epigallocatechin Gallate and Caffeine in the Extract of Waste Tea on Macroporous Adsorption Resins Functionalized with Chloromethyl, Amino, and Phenylamino Groups

According to the Friedel-Crafts and amination reaction, a series of macroporous adsorption resins (MARs) with novel structures were synthesized and identified by the Brunauer-Emmett-Teller (BET) method and Fourier transform infrared (FTIR) spectra, and corresponding adsorption behaviors for (-)-epigallocatechin gallate (EGCG) and caffeine (CAF) extracted from waste tea were systemically investigated. Based on evaluation of adsorption kinetics, the kinetic data were well fitted by pseudo-second-order kinetics. Langmuir, Freundlich, Temkin-Pyzhev, and Dubinin-Radushkevich isotherms were selected to illustrate the adsorption process of EGCG and CAF on the MARs. Thermodynamic parameters were adopted to explain in-depth information of inherent energetic changes associated with the adsorption process. The effect of temperature on EGCG and CAF adsorption by D101-3 was further expounded. Van der Waals force, hydrogen bonding, and electrostatic interaction were the main driving forces for the adsorption of EGCG and CAF on the MARs. This study might provide a scientific reference point to aid the industrial large-scale separation and enrichment of EGCG from the extracts of waste tea using modified MARs.

Preparative Separation and Purification of Rebaudioside A from Steviol Glycosides Using Mixed-Mode Macroporous Adsorption Resins

Preparative separation and purification of rebaudioside A from steviol glycosides using mixed-mode macroporous adsorption resins (MARs) were systematically investigated. Mixed-mode MARs were prepared by a physical blending method. By evaluation of the adsorption/desorption ratio and adsorption/desorption capacity of mixed-mode MARs with different proportions toward RA and ST, the mixed-mode MAR 18 was chosen as the optimum strategy. On the basis of the static tests, it was found that the experimental data fitted best to the pseudosecond-order kinetics and Temkin-Pyzhev isotherm. Furthermore, the dynamic adsorption/desorption experiments were performed on the mini column packed with mixed-mode MAR 18. After one run treatment, the purity of rebaudioside A in purified product increased from 40.77 to 60.53%, with a yield rate of 38.73% (W/W), and that in residual product decreased from 40.77 to 36.17%, with a recovery yield of 57.61% (W/W). The total recovery yield reached 96.34% (W/W). The results showed that this method could be utilized in large-scale production of rebaudioside A from steviol glycosides in industry.

Simultaneous separation and purification of flavonoids and oleuropein from Olea europaea L. (olive) leaves using macroporous resin

BACKGROUND This study developed a feasible process to simultaneously separate and purify polyphenols, including flavonoids and oleuropein, from the leaves of Olea europaea L. Macroporous resins were used as the separation and purification materials. The performance and separation capabilities of eight resins (D101, DM130, HPD450, LSA-21, LSA-40, 07C, LSD001 and HPD600) were systematically evaluated. The contents of target polyphenols in different extracts were determined using ultraviolet (for flavonoids) and high-performance liquid chromatographic (for oleuropein) methods. The static adsorption and desorption results showed that resin LSA-21 had better adsorption properties among the eight resins. Influential factors such as extraction method, pH value of feeding solution, desorption solution, adsorption kinetics and adsorption isotherm, etc. to the extraction and purification of these polyphenols were successively investigated on resin LSA-21. RESULTS The target flavonoids and oleuropein were selectively purified using resin LSA-21. Compared with the contents in raw leaves, the contents of total flavonoids and oleuropein in the final purified products were increased 13.2-fold (from 16 to 211 g kg(-1) ) and 7.5-fold (from 120 to 902 g kg(-1) ) with recovery yields of 87.9% and 85.6%, respectively. CONCLUSION This extraction and purification method could be used in the large-scale enrichment or purification of flavonoids, oleuropein and other polyphenols from O. europaea L. leaves or other herbal materials in industrial, food processing and medical manufacture.

Polysaccharides from Enteromorpha prolifera enhance the immunity of normal mice

The effects of polysaccharides from Enteromorpha prolifera (PEP) on cell-mediated immunity, humoral immunity and mononuclear phagocytic system function were evaluated to assess the immunomodulatory potential of these macromolecules. Relevant immunological mechanisms were verified by biochemical assays and western blot analysis. Results showed that PEP could induce splenocyte proliferation. In vivo experiments on Kunming mice confirmed that PEP could improve cell-mediated immunity, humoral immunity and mononuclear phagocytic system function. To illustrate the mechanism, we determined several immune-related enzymes in the thymus and spleen. The results indicated that PEP could enhance the activities of alkaline phosphatase, superoxide dismutase and lactate dehydrogenase. PEP could also increase the level of NF-κB. These results suggested that PEP exhibited potent immunomodulatory properties and could be used as a novel potential immunostimulant in food and pharmaceutical industries.

Cytotoxic Diarylheptanoids from the Pericarps of Walnuts (Juglans regia)

Two new diarylheptanoids, juglanin A (1) and B (2), together with 15 known compounds, were isolated from the extract of the seed husks of walnuts (Juglans regia L.). The structures of 1 and 2 were elucidated by various spectroscopic methods including intensive 2D-NMR techniques, HR-ESI-MS, and X-ray single-crystal diffraction analysis, and the cytotoxic activities of 1, 2, and 10 against human hepatoma (Hep G2) cells was reported.

Study on the adsorption feature of rutin aqueous solution on macroporous adsorption resins.

The adsorption feature of different kinds of polystyrene-based macroporous adsorption resins (MARs) was investigated systemically at constant temperature employing Rutin as the adsorbate. Different from traditional adsorption patterns, Langmuir and Freundlich adsorption, and the results showed interesting aspects: (1) With the increase of the volume of the initial solution, the adsorption capacity increased to the maximum, and then decreased gradually. (2) Experimental results clearly verified the opinion that the adsorption process of MARs could be divided into three stages-macropores, mesopores, and micropores-by the capillary effects occurring at the two intersections, and the adsorption feature for every stage could be described well by the fourth type of Brunauer model. (3) The model that the inductive effect transmitted to the first layer could not interpret our experimental results reasonably. Thus, the model that the inductive effect passed on to a higher layer was proposed by investigating regression of the experimental results and the conclusion that the inductive effect transmitted to the third layer was drawn.

A metabolic profiling analysis of symptomatic gout in human serum and urine using high performance liquid chromatography-diode array detector technique

BACKGROUND Uric acid (UA) is the only biomedical indicator for gout in clinic that always leads to an uncertain diagnose. Due to the lack of reliable metabolites, it is now already highly desirable to diagnose gout definitely. METHODS Metabonomics was employed to screen and identify novel biomarkers of gout based on human serum and urine. High performance liquid chromatography-diode array detector (HPLC-DAD) and orthogonal signal correction partial least squares discriminate analysis (OSC-PLS-DA) were also used for metabonomics study. RESULTS Several potential biomarkers including uric acid, creatinine, tryptophan in serum and uric acid, creatinine, guanosine, hippuric acid in urine, were respectively screened and identified. For serum and urine, the predictive levels about the OSC-PLS-DA models of the gout and controls were 95.76% and 100%, and the correction levels about the seriousness of the disease were 90.32% and 87.5%, respectively. CONCLUSION Compared with intermittent gout, the acute gout shows clearly the dysfunctions of purine, protein and glucose metabolism. The metabolizing of guanosine to UA increases the levels of UA in serum at the acute stage. Our research contributes to a better understanding of the metabolic mechanism and allowing the targeted therapy of gout at different stages.

Preparative separation and purification of Rebaudioside A from Stevia rebaudiana Bertoni crude extracts by mixed bed of macroporous adsorption resins

The separation and purification of Rebaudioside A (RA) from Stevia rebaudiana Bertoni crude extracts (Steviosides) by macroporous adsorption resin (MAR) mixed bed were systematically investigated. MAR mixed bed of HPD750-LSA40-LSA30-DS401 was selected due to its better separation degree. Based on the kinetics/thermodynamics experiment of the mixed bed, it was found that the experimental data fitted better to the pseudo-second-order model, and intra-particle diffusion was rate-limiting step. The adsorption isotherm was consistent with IV equilibrium adsorption isotherm classified by Brunauer. Furthermore, the influencing factors for the separation of RA based on HPLC were also investigated. Under the optimal conditions, the separation degree for RA (DAS) increased from 0.771 to 1.54. Moreover, the experimental results showed that the purity of the obtained product increased from 60% to 97%.

New way to analyze the adsorption behavior of flavonoids on macroporous adsorption resins functionalized with chloromethyl and amino groups

A series of macroporous adsorption resins (MARs) with novel structure were synthesized on the basis of the Friedel-Crafts catalyzed and amination reaction. Adsorption feature of the synthetic resins with respect to the purification effect were investigated systemically by employing rutin as the adsorbate. Different from traditional adsorption patterns, the results showed interesting conclusions: (1) With the increase in the temperature of the experiment, the adsorption capacity increased gradually; with the increase in the concentration of the initial solution, the adsorption capacity increased to the maximum and then decreased gradually. (2) The classical models that the inductive effect transmitted to the first layer and the adsorption process contained in one compartment could not explain our experimental results reasonably. Thus, a new adsorption isotherm model that the inductive effect passed on to a higher layer and a new adsorption kinetics model in which the adsorption process contained more compartments were created according to the multiparameter theory and Karickhoffs theory by investigating the regression of the experimental results. The conclusion that the inductive effect passed to the fourth layer and the adsorption process contained four compartments was drawn.

Simultaneous determination of three diarylheptanoids and an α-tetralone derivative in the green walnut husks (Juglans regia L.) by high-performance liquid chromatography with photodiode array detector

By optimizing extraction, separation and analytical conditions, a reliable and accurate high-performance liquid chromatographic (HPLC) method coupled with photodiode array detector (DAD) at room temperature is developed for simultaneous determination of three diarylheptanoids (juglanin A, juglanin B, rhoiptelol) and an alpha-tetralone derivative (regiolone) in methanol extracts from the green walnut husks (Juglans regia L.) The sample pretreatment process involved the reflux extraction using methanol as the extract with a ratio of liquor to sample of 15 mL/g. The separation was achieved on a SinoChrom ODS-AP C(18) column with gradient elution using acetonitrile and 2% (v/v) acetic acid in water. The intra-day and inter-day precision (RSD%) for the analytes ranged from 1.08 to 1.51 and 0.60 to 1.13, respectively. The average recoveries obtained were from 88.4% to 96.2% for the analytes with RSDs below 3.13%. The correlation coefficients of the calibration curve exceeded 0.999. The detection limits were 0.51, 0.25, 0.32 and 0.35 ng at a signal-to-noise ratio of 3, respectively. Quantitative analyses of the samples from different grown sites and in obtained different months showed that the contents of the analytes varied significantly. The method was then successfully applied for the detection and isolation of a new diarylheptanoid derivative in the green walnut husks (J. regia L.). The structure of the new compound was elucidated by various spectroscopic methods including 2D NMR techniques (COSY, HMQC, HMBC), HR-ESI-MS and X-ray single-crystal diffraction analysis.