Application of stable isotope dilution liquid chromatography-mass spectrometry in medical research / 国际药学研究杂志

Stable isotope dilution mass spectrometry(ID-MS)is a quantitative method for determining the content of unla?beled compounds with stable isotope labeled compounds as internal standard. Stable isotope dilution liquid chromatography-mass spec?trometry(ID-LC-MS)has the advantages of high sensitivity,no quantitative separation of the analytes,and effective elimination of the biological matrices. The method has been widely used in quantitative analysis of biomarkers,drugs and their metabolites. In this pa?per,the mechanism and characteristics of ID-LC-MS are briefly introduced,and its medical applications are summarized.

Isoprenoids and phenylpropanoids from Saussurea deltoidea / 中国中药杂志

To investigate the chemical constituents of Saussurea deltoidea, 10 compounds were isolated from the title plant by various chromatography methods such as silica gel, RP-18 silica gel, Sephadex LH-20 column chromatography, HPLC, et al. Their structures were elucidated by spectral analysis. Five isoprenoids and Five phenylpropanoids were isolated and elucidated as (3R, 6R, 7E) -3-hydroxy-4, 7-megastigmadien-9-one (1), (3S, 5R, 6S, 7E) -5, 6-epoxy-3-hydroxy-7-megastigmen-9-one (2), 3-hydroxy-beta-damascone (3), S-(+) -dehydrovomifoliol (4), megastigman-5-ene-3beta, 9R-diol (5), coniferaldehyde (6), beta-hydroxypropiovanillone (7), 3-hydroxy-1-(4-hydroxy-3, 5-dimethoxyphenyl) -1-propanone (8), dihydrosyringenin (9), 4-[(1S) -3-hydroxy-1-methoxypropyl]-2, 6-dimenthoxyphenol (10). All the compounds were isolated from S. deltoidea for the first time.

Tyrosinase inhibition of Potentilla bifurca / 中国中药杂志

<p><b>OBJECTIVE</b>To identify the tyrosinase inhibitory constituent quickly from Potentilla bifurca.</p><p><b>METHOD</b>The active constituent was found through fraction collecting and tyrosinase inhibitory activity by bioassay-linked HPLC method.</p><p><b>RESULT</b>The methanol extracts and BuOH fraction of Potentilla bifurca showed strong tyrosinase inhibitory activities. From BuOH fraction of Potentilla bifurca, the tyrosinase inhibitory constituent was isolated and identified as flavonoid, quercetin-4'-O-beta-D-glucoside. It express stronger tyrosinase inhibition than the known tyrosinase inhibitor, kojic acid (IC50 = 0.28 mmol x L(-1)) with IC50 value of 0.001 9 mmol x L(-1).</p><p><b>CONCLUSION</b>Bioassay-linked HPLC fractionation method was provided for determination the active constituents quickly from herbal medicines.</p>

Tyrosinase inhibitor from Angelica dahurica roots / 中国中药杂志

<p><b>OBJECTIVE</b>To isolate and identify the tyrosinase inhibitory constituent from Angelica dahurica.</p><p><b>METHOD</b>A tyrosinase inhibitory constituent was isolated by silica gel column chromatography combined with a bioassay-linked HPLC method.</p><p><b>RESULT</b>An extract of heat-processed A. dahurica roots showed more potent tyrosinase inhibitory activity than that of the crude drug. Tyrosinase inhibitory furanocoumarin, 8-hydroxy-5-methoxypsoralen,was isolated. It express stronger tyrosinase inhibition than the known tyrosinase inhibitor, kojic acid (IC50 = 0.0907 mmol x L(-1)) with IC50 value of 0.0086 mmol x L(-1). Therefore, it is contributive to the increased tyrosinase inhibitory activity of the heat-processed A. dahurica.</p><p><b>CONCLUSION</b>The active constituent was 8-hydroxy-5-methoxypsoralen from the heat-processed A. dahurica.</p>