Recognition mechanism of water-compatible molecularly imprinted solid-phase extraction and determination of nine quinolones in urine by high performance liquid chromatography.

Novel water-compatible molecularly imprinted polymers (MIPs) were synthesized in methanol-water systems with ofloxacin as templates and methacryclic acid as functional monomers. The MIPs were used as a special sorbent for the selective solid-phase extraction (SPE) of nine quinolones from urine samples, showing high affinity to the quinolones in aqueous environment. Its molecular recognition mechanisms were investigated by the molecular simulation and the experimental validation with UV and infrared spectrogram as well as (1)H NMR. Binding capability and chromatographic characteristic were also evaluated. By using the water-compatible MIPs as SPE sorbents, the nine quinolones can be selectively extracted and enriched, while all matrices interferences were eliminated simultaneously. Under the optimal conditions of SPE and high performance liquid chromatography (HPLC), the good linearity of the method was obtained in a range of 0.05-30microg/mL with the correlation coefficient of >0.999 and the relative standard division of 2.0-7.4%. The detection limits (s/n=3) were in a range of 0.036-0.10microg/mL. The proposed method was successfully applied for the selective extraction and separation of the studied quinolones in urine samples.

Characteristic of theophylline imprinted monolithic column and its application for determination of xanthine derivatives caffeine and theophylline in green tea.

Theophylline imprinted monolithic columns were designed and prepared for rapid separation of a homologous series of xanthine derivatives, caffeine, and theophylline by an in situ thermal-initiated copolymerization technique. Caffeine and theophylline were fully separated both under isocratic and gradient elutions on this kind of monolithic molecularly imprinted polymers (MIP) column. The broad peak showed in isocratic elution could be improved in gradient elution. Some chromatographic conditions such as mobile phase composition, flow rate, and the temperature on the retention times were investigated. Hydrogen bonding interaction and hydrophobic interaction played an important role in the retention and separation. The binding capacity was evaluated by static adsorption and Scatchard analysis, which showed that the dissociation constant (KD) and the maximum binding capacity (Qmax) were 1.50 mol/L, and 236 micromol/g for high affinity binding site, and 7.97 mol/L and 785 micromol/g for lower affinity binding site, respectively. Thermodynamic data (DeltaDeltaH and DeltaDeltaS) obtained by Van't Hoff plots revealed an enthalpy-controlled separation. The morphological characteristics of monolithic MIP were investigated by scanning electron microscope, which showed that both mesopores and macropores were formed in the monolith. The present monolithic MIP column was successfully applied for the quantitative determination of caffeine and theophylline in different kinds of green tea.

Experimental treatment of complications in alloxan diabetic rats with alpha-glucosidase inhibitor from the Chinese medicinal herb ramulus mori.

AIM: To assess the effects of the alpha-glucosidase inhibitor Sangzhi (Ramulus mori, SZ) on the relief of diabetic symptoms of hyperglycemia and the prevention of its late complications in alloxan diabetic rats with high-calorie chow. METHODS: The aqueous extract of Sangzhi was given orally to alloxan diabetic rats for 15 days. The hyperglycemic symptoms were observed. The blood glucose, lipid levels and the nephrotic representations were measured. RESULTS: When alloxan diabetic rats on high-calorie chow were treated with SZ, the hyperglycemic symptoms were improved, the blood lipid levels were improved, the ratio of kidney over body weight and the blood N-acetyl-beta-D-glucosaminidase (NAG) activity were lowered. The degree of renal pathological changes was significantly reduced. CONCLUSION: SZ may be useful for treating diabetes and its complications.