S.P. Li

Discrimination of polysaccharides from traditional Chinese medicines using saccharide mapping—Enzymatic digestion followed by chromatographic analysis

Polysaccharides isolated from traditional Chinese medicines (TCMs) exhibit multiple pharmacological activities. However, quality control of polysaccharides is a challenge because of their complicate structure and macro-molecular mass. In this study, saccharide mapping based on specific enzymatic digestion of polysaccharides and chromatographic analysis was proposed to discriminate the polysaccharides from different TCMs. Endo-carbohydrase such as glucanase, arabinanase, xylanase, galactanase, cellulase, amylase and pectinase were used for enzymatic digestion of polysaccharides from 9 TCMs namely Panax ginseng, P. notoginseng, P. quinquefolium, Cordyceps sinensis, C. militaris, Ganoderma lucidum, G. sinense, Astragalus membranaceus and Angelica sinensis. By using high performance size exclusion chromatography (HPSEC) as well as derivatization with 1-Phenyl-3-methyl-5-pyrazolone (PMP) and HPLC analysis, the enzymatic hydrolysis properties of polysaccharides and their saccharide mapping were determined. The polysaccharides from 9 TCMs were firstly successfully distinguished based on their characteristic saccharide maps, which is helpful to improve the quality control of polysaccharides.

Analysis of sterols and fatty acids in natural and cultured Cordyceps by one-step derivatization followed with gas chromatography-mass spectrometry

Ten free fatty acids namely lauric acid, myristic acid, pentadecanoic acid, palmitoleic acid, palmitic acid, linoleic acid, oleic acid, stearic acid, docosanoic acid and lignoceric acid and four free sterols including ergosterol, cholesterol, campesterol and beta-sitosterol in natural (wild) Cordyceps sinensis, Cordyceps liangshanensis and Cordyceps gunnii, as well as cultured C. sinensis and Cordyceps militaris were first determined using pressurized liquid extraction (PLE), trimethylsilyl (TMS) derivatization and GC-MS analysis. The conditions such as the amount of reagent, temperature and time for TMS derivatization of analytes were optimized. Under the optimum conditions, all calibration curves showed good linearity within the tested ranges. The intra- and inter-day variations for 14 investigated compounds were less than 3.4% and 5.2%, respectively. The results showed that palmitic acid, linoleic acid, oleic acid, stearic acid and ergosterol are main components in natural and cultured Cordyceps which could be discriminated by hierarchical clustering analysis based on the contents of 14 investigated compounds or the 4 fatty acids, where the contents of palmitic acid and oleic acid in natural Cordyceps are significantly higher than those in the cultured ones.

Advanced development in chemical analysis of Cordyceps.

Cordyceps sinensis, also called DongChongXiaCao (winter worm summer grass) in Chinese, is a well-known and valued traditional Chinese medicine. In 2006, we wrote a review for discussing the markers and analytical methods in quality control of Cordyceps (J. Pharm. Biomed. Anal. 41 (2006) 1571-1584). Since then this review has been cited by others for more than 60 times, which suggested that scientists have great interest in this special herbal material. Actually, the number of publications related to Cordyceps after 2006 is about 2-fold of that in two decades before 2006 according to the data from Web of Science. Therefore, it is necessary to review and discuss the advanced development in chemical analysis of Cordyceps since then.

Simultaneous determination of five flavonoids in licorice using pressurized liquid extraction and capillary electrochromatography coupled with peak suppression diode array detection.

Pressurized liquid extraction (PLE) and capillary electrochromatography (CEC) methods were developed for the simultaneous determination of five flavonoids, namely liquiritin, isoliquiritin, ononin, liquiritigenin and isoliquiritigenin, in licorice using baicalein as internal standard (IS). Peak suppression technique was used for the quantification of ononin because of its poor resolution with isoliquiritin. The analysis was performed on a Hypersil C(18) capillary (3 microm, 100 microm/25 cm) with a mixture of 10mM phosphate buffer (pH 3.0)/ACN (65:35, v/v) as mobile phase running at 25 kV and 30 degrees C. The detection wavelengths were set at 275 nm (without reference wavelength for liquiritin and liquiritigenin), 360 nm (without reference wavelength for isoliquiritin and isoliquiritigenin) and 254 nm (with reference wavelength of 405 nm for ononin). All calibration curves showed good linearity (R(2)>0.9993) within the test ranges. The LOD and LOQ were lower than 2.1 and 8.3 microg/mL, respectively. The RSDs of intra- and interday for relative peak areas of five analytes to IS were less than 3.8 and 4.7%, respectively, and the recoveries were 98.2-103.8%. The validated method was successfully applied to the quantitative analysis of five flavonoids in licorice, which is helpful to its quality control.

Simultaneous determination of nucleobases, nucleosides and saponins in Panax notoginseng using multiple columns high performance liquid chromatography

A new multiple columns HPLC method for simultaneous determination of 16 characteristic components, 5 nucleobases and nucleosides (uracil, cytidine, uridine, guanosine and adenosine), and 11 saponins (notoginsenoside R1, ginsenoside Rg1, ginsenoside Re, notoginsenoside R4, notoginsenoside Fa, ginsenoside Rb1, notoginsenoside R2, ginsenoside Rg2, ginsenoside Rh1, ginsenoside Rd and notoginsenoside K), in the root of Panax notoginseng, a valued traditional Chinese medicinal herb, were developed. Notoginsenoside R4, Fa and K were first quantitatively determined in P. notoginseng. The 5 nucleobases and nucleosides compounds were separated on a Zorbax SB-Aq column (150 x 4.6 mm, 5.0 microm) and 11 saponins were analyzed using a Zorbax Bonus-RP column (150 x 4.6 mm, 5.0 microm) with column switching. The column temperature was set at 30 degrees C. Mobile phase was composed of 5mM ammonium acetate aqueous (A), water (B) and acetonitrile (C) using a gradient elution. The flow rate was 1.5 mL/min and detection wavelengths were set at 260 nm for nucleobases and nucleosides, and 203 nm for saponins. The developed method had good repeatability and sensitivity for quantification of 16 analytes with overall precision (including intra- and inter-day) less than 3% (RSD), and LOD and LOQ were less than 1.33 microg/mL and 5.12 microg/mL, respectively. The method was successfully applied to the simultaneous determination of 16 analytes in 15 samples of P. notoginseng collected from different places of China, which indicated that multiple columns HPLC can be used for comprehensive quality control of P. notoginseng.

Rapid method for simultaneous determination of flavonoid, saponins and polyacetylenes in Folium Ginseng and Radix Ginseng by pressurized liquid extraction and high-performance liquid chromatography coupled with diode array detection and mass spectrometry

A rapid pressurized liquid extraction (PLE) and high-performance liquid chromatography coupled with diode array detection and mass spectrometry (HPLC-DAD-MS) method for the simultaneous determination of one flavonoid (panasenoside), nine saponins (ginsenoside Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2, Rb3 and Rd) and two polyacetylenes (panaxydol and panaxynol) in folium ginseng and radix ginseng was developed. A Prevail C(18) rocket column (33 mm x 7 mm, 3.0 microm) and gradient elution were used during the analysis. Flavonoid was quantified at 355 nm, and saponins and polyacetylenes were determined at 203 nm. The chromatographic peaks of 12 investigated compounds in samples were unambiguously identified by compared their UV spectra and/or MS data with the related reference compounds. All calibration curves showed good linearity (r>0.999) within the test ranges. The intra- and inter-day variations for 12 analytes were less than 1.17% and 2.17%, respectively. The developed method was successfully applied to determine the investigated compounds in 10 samples of radix ginseng and folium ginseng, respectively. The result showed that PLE combined with rocket column HPLC analysis could provide a rapid method for analysis of compounds in traditional Chinese medicines (TCMs), which is helpful to comprehensive evaluation of quality of radix ginseng and folium ginseng.

Qualitative and quantitative analysis of four species of Curcuma rhizomes using twice development thin layer chromatography.

The rhizomes of Curcuma phaeocaulis, Curcuma kwangsiensis, Curcuma wenyujin and Curcuma longa are used as Ezhu or Jianghuang in traditional Chinese medicine for a long time. Due to their similar morphological characters, it is difficult to distinguish their origins of raw materials used in clinic. In this study, a simple, rapid and reliable twice development TLC method was developed for qualitative and quantitative analysis of the four species of Curcuma rhizomes. The chromatography was performed on silica gel 60F(254) plate with chloroform-methanol-formic acid (80:4:0.8, v/v/v) and petroleum ether-ethyl acetate (90:10, v/v) as mobile phase for twice development. The TLC markers were colorized with 1% vanillin-H(2)SO(4) solution. The four species of Curcuma were easily discriminated based on their characteristic TLC profiles, and simultaneous quantification of eight compounds, including bisdemethoxycurcumin, demethoxycurcumin, curcumine, curcumenol, curcumol, curdione, furanodienone and curzerene, in Curcuma were also performed densitometrically at lambda(scan)=518nm and lambda(reference)=800 nm. The investigated compounds had good linearity (r(2)>0.9905) within test ranges. Therefore, the developed TLC method can be used for quality control of Curcuma rhizomes.

Comparison of polysaccharides from different Dendrobium using saccharide mapping

Multiple species of Dendrobium are widely used as Shihu, a well known Chinese herb, for medicinal purpose in China. Small molecules such as phenols, alkaloids and coumarins are obviously varied in different species of Dendrobium. But there are few reports on polysaccharides, one of major active components, from Dendrobium. In this study, polysaccharides from different species or locations of Dendrobium were compared using saccharide mapping. The results showed that polysaccharides of Dendrobium from different species or locations were obviously varied in spite of they had some similar characters, which is helpful to control the quality of Dendrobium.

Quality evaluation of Polygonum multiflorum in China based on HPLC analysis of hydrophilic bioactive compounds and chemometrics

Polygonum multiflorum is one of the most commonly used Chinese medicines. In this study, an effective pressurized water extraction and HPLC method was developed for first simultaneous determination of 8 hydrophilic compounds, including gallic acid, Hypaphorine, Catechin, Proanthocyanidin B1, Epicatechin, Proanthocyanidin B2, Emodin-8-O-β-d-glucopyranoside, stilbene glycosides, in P. multiflorum. The analysis was performed on a Zorbax SB-AQ column with gradient elution of 0.05% phosphoric acid aqueous solution and acetonitrile in 45 min. All calibration curves showed good linearity (R(2)>0.9994) within test ranges. The LOD and LOQ were lower than 0.2 and 1.0 μg/mL on column, respectively. RSD for intra- and inter-day of 8 analytes were less than 4.1% and 4.0%, respectively, and the overall recovery was 96.0-100.7%. The validated method was successfully applied to quantification of 8 hydrophilic compounds in samples of P. multiflorum from different locations of China. Chemometrics such as principal component analysis (PCA) and hierarchical clustering analysis (HCA) were used to evaluate homogeneity of P. multiflorum in China, which suggested that their quality homogeneity was good.

A novel sample preparation and on-line HPLC–DAD–MS/MS–BCD analysis for rapid screening and characterization of specific enzyme inhibitors in herbal extracts: Case study of α-glucosidase

Drug discovery from complex mixture like Chinese herbs is a challenge and extensive false positives make the obtainment of specific bioactive compounds difficult. In the present study, a novel sample preparation method was proposed to rapidly reveal the specific bioactive compounds from complex mixtures using α-glucosidase as a case. Firstly, aqueous and methanol extracts of 500 traditional Chinese medicines were carried out with the aim of finding new sources of α-glucosidase inhibitors. As a result, the extracts of fruit of Terminalia chebula (FTC), flowers of Rosa rugosa (FRR) and Eugenia caryophyllata (FEC) as well as husk of Punica granatum (HPG) showed high inhibition on α-glucosidase. On-line liquid chromatography-diode array detection-tandem mass spectrometry and biochemical detection (HPLC-DAD-MS/MS-BCD) was performed to rapidly screen and characterize α-glucosidase inhibitors in these four extracts. After tentative identification, most of compounds with inhibitory activity in the investigated crude extracts were found to be tannins commonly recognized as non-specific enzyme inhibitors in vitro. Subsequently, the four extracts were treated with gelatin to improve specificity of the on-line system. Finally, two compounds with specific α-glucosidase inhibition were identified as corilagin and ellagic acid. The developed method could discover specific α-glucosidase inhibitors in complex mixtures such as plant extracts, which could also be used for discovery of specific inhibitors of other enzymes.