| Alginate is a linear block compound,which is composed ofβ-D-mannose uronic acid (M) andα-L-guluronic acid (G). Anti-cardiovascular drugs PSS, lipid-lowering drugs PMS, anti-urolithiasis drugs PGS are three drugs based on the sodium alginate, ploymannuronic acid and polyguluronic acid as the main raw materials sulfate derivatives. Because of M and G for the C5 epimer, it makes these three drugs in the structure and physico-chemical properties very similar. It is difficult to separate these three drugs through quality standards in general. At present, a fast and easy detection method in vivo and in vitro is not used, especially the small amount of research methods. In this paper, based on the PSS, PMS and PGS three marine drugs of different uronic acid components, the method of a suitable microanalysis of three drugs in the pre-column derivatization high-performance liquid chromatography and high-performance anion chromatography with pulsed amperometric detection is established.In this paper, alginate as raw material is degraded by acid, then precipitayed by ethanol–acetone(1:1). G and M mixture obtained from the supernatant. M and G monosaccharide standard are separated by gel exclusion chromatography and ion-exchange chromatography. After PSS, PMS and PGS are degraded by trifluoroacetic acid (TFA), and carried out pre-column derivatization with 1-phenyl -3-methyl-5-pyrazolone (PMP), Then the three drugs uronic acid composition is analysd by high-performance liquid chromatography. Results show that the optimum degradation conditions of PSS, PMS and PGS are as follows: the reaction temperature is 110℃, the reaction time is 6 h and the concentration of TFA is 3 mol/L. The optimum derivation conditions are as follows: the reaction temperature is 70℃, the reaction time is 90 min, the molar ratio of PMP to uronic acid is 12:1, and the molar ratio of NaOH to uronic acid is 2:1. The chromatographic conditions are as follows: the mobile phase consists of 0.1 mol/L phosphate buffer-acetonitrile (V/V, 82: 18) at a flow rate of 1 mL/min, and the detection wavelength at 245 nm. M and G are well separated under the optimum chromatographic conditions. The M/G ratios of PSS, PMS and PGS determined by HPLC are 2.37±0.05, 6.60±0.22 and 0.22±0.03, respectively. Sample recovery is about 97.6% 101.2%. Detection limit is 5.2×10-3 nmol(1.01ng). The method has good precision and reproducibility, low detection which is suitable for the microanalysis of marine brown alga polysaccharide drugs.And through the use of ion-exchange CarboPac PA 20 column with Au as the working electrode, Ag / AgCl as reference electrode, another method of a suitable mi croanalysis of three drugs is established by high-performance anion chromatography with pulsed amperometric detection. The results showed that optimal conditions for PSS, PMS, PGS degradation is temperature 115℃, the degradation time 4 h and TFA concentration of 3 mol/L; the best chromatographic conditions are as follows mobile phase: 100 mmol / L NaAc / 20 mmol / L NaOH, flow rate: 0.4mL/min, column temperature: 20℃at the chromatographic conditions, mannuronic acid (M) and guluronic acid (G) have a good separation. The M/G ratios of PSS, PMS and PGS determined by HPAEC are 2.06±0.06, 6.21±0.08 and 0.04±0.05, sample recovery is about 90.1% 98.0%. Detection limit is 6.4×10-3nmol(1.25ng). The method has good precision and reproducibility, low detection limit, the sample can be directly derived without derivatization, fit in the trace analysis of polysaccharide drugs. This paper set up pre-column derivatization high-performance liquid chromatogr aphy and high-performance anion chromatography with pulsed amperometric detection trace analysis method of three marine brown algae polysaccharide drugs.This method provides the basis of their quality control, qualitative and quantitative analysis. Because the body does not contain M and G , we can get rid of the possibility of endogenous uronic acid interference, so the method can also be used as microanalysis of these three drugs in vivo and pharmacokinetic study.
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