Tao Yi

Publications of Tao Yi

• Study of the relationship between genetics and geography in determining the quality of Astragali Radix.

  Authors: Jing Liu, Hu-Biao Chen, Bao-Lin Guo, Zhong-Zhen Zhao, Zhi-Tao Liang, Tao Yi

  Biological & pharmaceutical bulletin. 01/2011; 34(9):1404-12.

  Astragali Radix (AR), prepared from the roots of Astragalus membranaceus (FISCH. ex LINK) BUNGE or its variey, A. membranaceus (FISCH. ex LINK) BUNGE var. mongholicus (BUNGE) HSIAO., is one of theAstragali Radix (AR), prepared from the roots of Astragalus membranaceus (FISCH. ex LINK) BUNGE or its variey, A. membranaceus (FISCH. ex LINK) BUNGE var. mongholicus (BUNGE) HSIAO., is one of the most used and valuable traditional Chinese medicines (TCMs). Historically, Hunyuan, Shanxi Province in China is the geo-authentic producing area of AR and crude AR from here called "geo-authentic." According to tradition, geo-authentic TCMs define both authenticity and quality. However, no scientific investigation has ever determined whether the superior quality of Hunyuan AR is due to the genetic characteristics or to the local environment. In our study, seeds of 30 AR samples representing the two varieties from different regions were cultivated in Hunyuan under the same conditions. A method, using ultra-performance liquid chromatography coupled with photodiode array detector and evaporative light scattering detectors, was developed to evaluate the quality through a simultaneous determination of four major isoflavonoids and four major saponins. The two AR varieties were successfully distinguished by principal component analysis while samples of the same species with different seeds origins could not be distinguished. A genetic study demonstrated that the internal transcribed spacer sequences of the nuclear ribosomal DNA in A. membranaceus var. mongholicus samples from different geographical regions were highly conservative. These results indicate that the content of active components in AR depends on the interaction of genotype and environment. At the varietal level, genetic properties appear to be more important for pharmaceutical quality than environmental factors, while on the intraspecific level environmental factors might be more important than genetic properties.

• Comparison of the chemical profiles and anti-platelet aggregation effects of two "Dragon's Blood" drugs used in traditional Chinese medicine.

  Authors: Tao Yi, Hu-Biao Chen, Zhong-Zhen Zhao, Zhi-Ling Yu, Zhi-Hong Jiang

  Journal of ethnopharmacology. 11/2010; 133(2):796-802.

  "Dragon's Blood" has been used as a medicine since ancient times by many cultures. In traditional Chinese medicine, the resin obtained from Daemonorops draco (RDD) and the resin from Dracaena"Dragon's Blood" has been used as a medicine since ancient times by many cultures. In traditional Chinese medicine, the resin obtained from Daemonorops draco (RDD) and the resin from Dracaena cochinchinensis (RDC) are equally prescribed as "Dragon's Blood" for facilitating blood circulation. To verify the traditional efficacy and elucidate the mechanism, the present study compared the chemical profiles and the pharmacological effects of two species of "Dragon's Blood" mainly used in China. A UPLC-MS fingerprinting method was developed to compare the chemical profiles of the two medicines. The anti-platelet aggregation effects of the two medicines induced by arachidonic acid (AA) were investigated. The chemical profiles of these two species of "Dragon's Blood" were significantly different. The characteristic constituents were found to be: flavanes in RDD and stilbenes in RDC. In the in vivo platelet inhibition test, performed with the dose of 200 mg/kg on rats, the peak inhibitory effects of RDD and RDC were 35.8% and 27.6%, respectively, compared with the control group. With the in vitro concentrations of 0.2, 0.4 and 0.8 mg/ml, RDD exerted significant inhibition of aggregation by 18.7%, 20.0%, and 61.6%, respectively, and RDC exerted significant inhibition of aggregation by 13.3%, 20.2%, and 31.6%, respectively. The fingerprinting method used here is suitable for distinguishing them. All pharmacological tests indicated that RDD was more potent than RDC against platelet aggregation.

• Comparison of the anti-inflammatory and anti-nociceptive effects of three medicinal plants known as "Snow Lotus" herb in traditional Uighur and Tibetan medicines.

  Authors: Tao Yi, Zhong-Zhen Zhao, Zhi-Ling Yu, Hu-Biao Chen

  Journal of ethnopharmacology. 03/2010; 128(2):405-11.

  Saussurea involucrata (Kar. et Kir.) Sch.-Bip. (Compositae) has long been used under the herbal name "Snow Lotus" for the treatment of rheumatoid arthritis, stomachache and dysmenorrhea in UighurSaussurea involucrata (Kar. et Kir.) Sch.-Bip. (Compositae) has long been used under the herbal name "Snow Lotus" for the treatment of rheumatoid arthritis, stomachache and dysmenorrhea in Uighur folk medicine. In traditional Tibetan medicine, Saussurea laniceps Hand.-Mazz. and Saussurea medusa Maxim. have also been used under the name "Snow Lotus" and prescribed for the treatment of pain and inflammatory conditions. The present study evaluated the pharmacological effects of three species of "Snow Lotus" in experimental inflammation and pain models, and determined the chemical compounds that may correlate with their pharmacological activities. The anti-inflammatory activities of the three herbs were observed by using carrageenan-induced paw edema in rats and xylene-induced ear edema in mice. Investigations on the analgesic effects were conducted, including acetic acid-induced writhing and hot-plate test. An UPLC-MS method was developed to analyze the chemical composition of the three herbs and of plasma samples after herb administration. In rat paw edema model, the peak inhibitory effects of Saussurea laniceps and Saussurea involucrata (55.1% and 42.2%, respectively) were recorded with the dose of 400mg/kg at 3h post-carrageenan injection. In mouse ear edema model, oral administration of Saussurea laniceps, Saussurea involucrata and Saussurea medusa extract (400mg/kg) resulted in a significant inhibition of ear edema by 40.9%, 33.3%, and 9.1%, respectively. In the writhing test, oral administration of Saussurea laniceps extract (100, 200 and 400mg/kg) resulted in a significant inhibition of writhings by 13.5%, 22.3%, and 43.5%, respectively. In the hot-plate test, Saussurea laniceps extract significantly increased the latency of jumping response by 38.2% and 52.7% when treated orally at 200 and 400mg/kg in mice, respectively. Flavonoids, coumarins and lignins were found to be present in plasma after administration of the extracts and may be the basis of the observed pharmacological effects. The results clearly demonstrated that Saussurea laniceps was most effective; Saussurea involucrata exhibited a moderate potency, whereas Saussurea medusa possessed little effect against the experimental edema and pains. This study also supported discrimination among the three herbs when using them in folk medicine.

• Comparison of the immunoregulatory function of different constituents in radix astragali and radix hedysari.

  Authors: Jing Liu, Xuguang Hu, Quan Yang, Zhiling Yu, Zhongzhen Zhao, Tao Yi, Hubiao Chen

  Journal of biomedicine & biotechnology. 01/2010; 2010:479426.

  Radix Astragali (RA), known as "Huangqi" in China, is one of the most popular herbal medicines known worldwide to reinforce "Qi". RA is traditionally prepared from the dried roots of AstragalusRadix Astragali (RA), known as "Huangqi" in China, is one of the most popular herbal medicines known worldwide to reinforce "Qi". RA is traditionally prepared from the dried roots of Astragalus membranaceus (MJHQ) and A. membranaceus var. mongholicus (MGHQ). Radix Hedysari is named "Hongqi" (HQ), which is similar to RA. We assessed and compared the chemical constituents and bioactivity of RA and HQ. Different constituents were extracted into five major parts and were analyzed using different methods. Comparison of the immunological effects of extracts was done by using two immunological models. Results showed that flavonoids and saponins present in RA and HQ were not only structurally significantly different but also different in their immunological effect. Amino acids extract (AE) in MGHQ shows immunological effect while AE in MJHQ and HQ did not. Polysaccharides comprised the major constituents in RA and HQ. All polysaccharides extract (PE) of the three herbs showed similar levels of immunological effect in both immunological assays.

• Anti-inflammatory activity of the extracts and fractions from Erigeron multiradiatus through bioassay-guided procedures.

  Authors: Pei Luo, Zhifeng Zhang, Tao Yi, Hao Zhang, Xinfu Liu, Zhengji Mo

  Journal of ethnopharmacology. 08/2008;

  ETHNOPHARMACOLOGICAL RELEVANCE: Erigeron multiradiatus (Lindl.) Benth., an herb that grows in the alpine and subalpine meadow of Qinghai-Tibet plateau, has been widely used as a folk remedy by theETHNOPHARMACOLOGICAL RELEVANCE: Erigeron multiradiatus (Lindl.) Benth., an herb that grows in the alpine and subalpine meadow of Qinghai-Tibet plateau, has been widely used as a folk remedy by the native people for treatment of various inflammatory ailments. AIM OF THE STUDY: In order to isolate and identify the active components of Erigeron multiradiatus for anti-inflammatory activity, a preliminary phytochemical study and a bioassay-guided fractionation and purification process was performed. MATERIAL AND METHODS: The dry whole plant Erigeron multiradiatus was extracted with 50% ethanol and then separated into CHCl(3), n-BuOH, and aqueous fractions. The anti-inflammatory activities of each fraction were investigated using two in vivo inflammation models. RESULTS: These results exhibited varying degrees of anti-inflammatory activities and the n-BuOH fraction showed the strongest anti-inflammatory activities. The n-BuOH fraction was then subjected to separation and purification using macroporous resins column chromatography and Sephadex LH-20 leading to two flavonoids glucuronides identified as scutellarein-7-O-beta-glucuronide and apigenin-7-O-beta-glucuronide. Furthermore, LC-MS/MS identification and quantification of isolated compounds were also performed. CONCLUSION: Scutellarein-7-O-beta-glucuronide and apigenin-7-O-beta-glucuronide were considered as major components and principally responsible for the anti-inflammatory activity of Erigeron multiradiatus. Thus the results of our study provide a scientific basis for the utilization of Erigeron multiradiatus in traditional Tibetan medicine.

• Comparison of the antiinflammatory activities of three medicinal plants known as "meiduoluomi" in Tibetan folk medicine.

  Authors: Zhifeng Zhang, Pei Luo, Jie Li, Tao Yi, Jiangang Wang, Jing An, Hao Zhang

  Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan. 06/2008; 128(5):805-10.

  Erigeron breviscapus (Vant.) Hand-mazz (EB), Erigeron multiradiatus (Lindl.) Benth (EM), and Aster brachytrichus Franch (AB), confused under the vernacular name "meiduoluomi" by native people andErigeron breviscapus (Vant.) Hand-mazz (EB), Erigeron multiradiatus (Lindl.) Benth (EM), and Aster brachytrichus Franch (AB), confused under the vernacular name "meiduoluomi" by native people and traditional healers, have been used for the treatment of meningitis, polyneuritis, hepatitis, adenolymphitis, and enteronitis in traditional Tibetan medicine. In this study, the antiinflammatory activity of methanol extracts of all three plants was investigated in the xylene-induced ear edema model, carrageenan-induced paw edema model, and cotton pellet-induced granuloma model. It was found that the methanolic extracts of both EB and EM had strong inhibitory effects on the acute phase of inflammation in carrageenan-induced paw edema in rats. On the other hand, the methanolic extract of EM showed stronger effects than those of EB in xylene-induced ear edema. In the chronic test, the methanolic extracts of EB and EM resulted in a significant reduction in granuloma weight in rats. In addition, myeloperoxidase (MPO) activity was strongly reduced in the EB-treated and EM-treated groups, which indicated that EB and EM can inhibit certain inflammatory modulator factors that cause neutrophil aggregation in inflamed tissue, e.g., nuclear factor-kappaB. However, the methanolic extracts of AB had no antiinflammatory effects in the tested models and MPO assay. The similar effects of EM and EB in tested models provided some scientific basis for the traditional usage of meiduoluomi in inflammatory disease. However, the results also suggest that further study is needed to investigate the antiinflammatory profile of AB and provide a scientific basis for the use of AB in inflammatory diseases.

• Application of microscopy in authentication of traditional Tibetan medicinal plant Halenia elliptica.

  Authors: Jie Li, Tao Yi, Hong-Shan Lai, Dan Xue, Hai Jiang, Huan-Chao Peng, Hao Zhang

  Microscopy research and technique. 02/2008; 71(1):11-9.

  Halenia elliptica D. Don, a popularly used ethnodrug from Qinghai-Tibetan plateau, was studied to reveal the indispensable morphoanatomic details. The fixed, sectioned, and stained plant materials asHalenia elliptica D. Don, a popularly used ethnodrug from Qinghai-Tibetan plateau, was studied to reveal the indispensable morphoanatomic details. The fixed, sectioned, and stained plant materials as well as the epidermis, powder, and maceration materials were studied using light microscope according to the usual microscopic techniques. The results of the microscopic features were systematic described and illustrated. In the root, an endodermal cell was divided into 8-16-22 and 38-50-62 daughter cells in transverse section and in face view, respectively, and 9-11-13 phloem strands were present in primary structure; in the stem, stone cells were observed in the cortex, pericycle, and external phloem while 17-19-21 internal phloem strands were present in an incontinuous ring; in the pedicel, 8-10-12 internal phloem strands were observed to form an incontinuous ring; anisocytic and anomocytic stomata were present in leaf and sepal epidermis; pollen grain was with three germinal apertures and furrows; a few tracheids, a large number of spiral vessels, and various fibers were observed. Also, semiquantitative and quantitative micrographic parameter tables were simultaneously presented. Further, the key authentication parameters were concluded. The study indicated that light microscopy and related techniques could be unambiguously applied to the authentication of Halenia elliptica.

• Analysis of Rhizoma Polygoni Cuspidati by HPLC and HPLC-ESI/MS.

  Authors: Tao Yi, Hao Zhang, Zongwei Cai

  Phytochemical analysis : PCA. 10/2007; 18(5):387-92.

  An HPLC method with photodiode array detection (PAD) and ESI/MS detection was developed for the qualitative and quantitative analysis of the major chemical constituents of the dried rhizome ofAn HPLC method with photodiode array detection (PAD) and ESI/MS detection was developed for the qualitative and quantitative analysis of the major chemical constituents of the dried rhizome of Polygonum cuspidatum Sieb. et Zucc. (Rhizoma Polygoni Cuspidati; Chinese name Hu-Zhang). Based on the chromatographic separation on an Altima C(18) column using 0.5% aqueous acetic acid and acetonitrile as the mobile phase, nine compounds, including stilbenes, stilbene glucosides, anthraquinones and anthraquinone glucosides, were identified by online ESI/MS analysis and seven were quantified by HPLC-PAD. A full validation of the method including sensitivity, linearity, repeatability and recovery was conducted. Linear calibration was achieved over the concentration range 1-200 mg/L with R(2) > 0.999, whilst the limits of detection ranged from 0.51 to 1.57 ng. Repeatability was evaluated by intra- and inter-day assays and the RSD value was within 1.79%. Recoveries of the quantified compounds were within the range 96.0-100.1% with RSD values of less than 2.2%. Five samples of Rhizoma Polygoni Cuspidati from different regions were analysed using the developed method. The major constituents piceid, resveratrol, emodin-8-O-beta-D-glucoside and emodin were selected to provide an index for the quality assessment of the herbal drug.

• A new procedure for the preparative separation and isolation of Z-ligustilide from the roots of Angelica sinensis.

  Authors: Tao Yi, Hao Zhang, Jing Xie, Dan Xue

  Journal of separation science. 09/2007; 30(12):1973-8.

  A new procedure for the separation and isolation of Z-ligustilide from the roots of Angelica sinensis (AS) was developed, and the storage conditions for Z-ligustilide were optimized. Using theA new procedure for the separation and isolation of Z-ligustilide from the roots of Angelica sinensis (AS) was developed, and the storage conditions for Z-ligustilide were optimized. Using the present procedure, Z-ligustilide was enriched by decomposing the Z-ligustilide dimers yielding Z-ligustilide and dissolving the polar impurities in hot water. Then, the crude Z-ligustilide was further purified by a semipreparative HPLC system. The spiked and nonspiked samples were used for the evaluation of the proposed procedure. Recoveries obtained varied from 86.2 to 90.7% and RSDs from 4.0 to 6.6%. The yield and purity of the isolated Z-ligustilide were found to be 4.57 mg/g and 99.6%, respectively. The results of stability tests have shown that the presence of oxidant contributes to Z-ligustilide degradation, therefore argon was chosen as a shielding gas for storage. The overall procedure is efficient and convenient which is considered suitable for the preparative separation of Z-ligustilide from AS.

• Comparative analysis of Ligusticum chuanxiong and related umbelliferous medicinal plants by high performance liquid chromatography-electrospray ionization mass spectrometry.

  Authors: Tao Yi, Kelvin Sze-Yin Leung, Guang-Hua Lu, Hao Zhang

  Planta medica. 05/2007; 73(4):392-8.

  A highly precise and accurate method, based on high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS), was developed for the qualitative and quantitativeA highly precise and accurate method, based on high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS), was developed for the qualitative and quantitative comparison of the main constituents in the rhizome of Ligusticum chuanxiong (LC) and three related umbelliferous medicinal plants. A comprehensive validation of the developed method was conducted, and the method was highly sensitive, reproducible and accurate. The unique properties of the present method were validated by analyzing 20 related herbal samples including 5 LC samples, 5 Cnidium officinale samples (CO), 5 Angelica sinensis samples (AS) and 5 Angelica acutiloba samples (AA). Twelve compounds including phenolic constituents, alkylphthalides and phthalide dimers were identified by online ESI-MS and by comparison with literature data and standard compounds, and six of them were quantified by HPLC-DAD simultaneously. The results demonstrated that identical compound types were identified as the main constituents of LC, CO, AS and AA herbs. The results also support the alternative application of these medicinal plants in Chinese and Japanese folk medicines. In the present study, it was found that the variation in the abundance of senkyunolide A was significant in these related herbs; it is therefore feasible to choose senkyunolide A as a characteristic compound for quality evaluation and chemical authentication of these herbs.

• Application of highly accurate nephelometric titration in the assaying of phenytoin sodium.

  Authors: Tao Yi, Xian-Cheng Zhan, Cheng-rong Li, Ning He

  Yao xue xue bao = Acta pharmaceutica Sinica. 05/2006; 41(4):370-5.

  AIM: To determine phenytoin sodium by a highly accurate nephelometric titration. METHODS: The titration operating conditions were optimized and the solubility product constant of phenytoin silverAIM: To determine phenytoin sodium by a highly accurate nephelometric titration. METHODS: The titration operating conditions were optimized and the solubility product constant of phenytoin silver precipitation was determined. RESULTS: The result of the titration is comparable to those of control experiments. CONCLUSION: The proposed method has been found to be accurate, precise, specific, reproducible, and linear.

• Determination of phenytoin sodium injection and tablets by highly accurate nephelometric titration.

  Authors: Tao Yi, Xian-Cheng Zhan, Cheng-rong Li, Ning He

  Chemical & pharmaceutical bulletin. 04/2006; 54(3):384-6.

  A highly accurate nephelometric titration method was developed for the quantitative analysis of phenytoin sodium injection and tablets. The titration operating conditions and the validation of theA highly accurate nephelometric titration method was developed for the quantitative analysis of phenytoin sodium injection and tablets. The titration operating conditions and the validation of the method were studied. Five batches of phenytoin sodium injection and tablets were determined by the proposed method and the control experiment methods, respectively. The results of the titration are comparable to those of control experiments. The proposed method is accurate and reproducible, which is considered suitable for the quantitative analysis of a large number of samples.

• Simultaneous qualitative and quantitative analyses of the major constituents in the rhizome of Ligusticum Chuanxiong using HPLC-DAD-MS.

  Authors: Tao Yi, Kelvin Sze-Yin Leung, Guang-Hua Lu, Kelvin Chan, Hao Zhang

  Chemical & pharmaceutical bulletin. 02/2006; 54(2):255-9.

  An HPLC-DAD-MS method was developed for the qualitative and quantitative analysis of the major constituents in Chuanxiong (the dried rhizome of Ligusticum chuanxiong Hort). Twenty compounds includingAn HPLC-DAD-MS method was developed for the qualitative and quantitative analysis of the major constituents in Chuanxiong (the dried rhizome of Ligusticum chuanxiong Hort). Twenty compounds including phenolic constituents, alkylphthalides and phthalide dimers were identified using online ESI-MS and comparisons with literature data and standard compounds, and six of them were quantified by HPLC-DAD simultaneously. A comprehensive validation of the method including sensitivity, linearity, repeatability and recovery was conducted. The linear regressions were acquired with R(2) > 0.99 and limit of detection (LOD, S/N = 3) values were between 1.5 and 2.5 ng. The repeatability was evaluated by intra- and inter-day assays, and relative standard deviation (RSD) values were reported within 1.87%. The recovery studies for the quantified compounds were observed in the range of 96.36-102.37% with RSD values less than 2.63%. These phenolic constituents and alkylphthalides, the major constituents in Chuanxiong, are generally regarded as the index for the quality assessment of this herb. The overall procedure is accurate and reproducible, which is considered suitable for the qualitative and quantitative analyses of a large number of Chuanxiong samples.

• Identification and comparative determination of senkyunolide A in traditional Chinese medicinal plants Ligusticum chuanxiong and Angelica sinensis by HPLC coupled with DAD and ESI-MS.

  Authors: Tao Yi, Kelvin Sze-Yin Leung, Guang-Hua Lu, Hao Zhang, Kelvin Chan

  Chemical & pharmaceutical bulletin. 11/2005; 53(11):1480-3.

  Using the HPLC/DAD/ESI/MS method, the qualitative and quantitative analysis of senkyunolide A (SA) in the rhizomes of Ligusticum chuanxiong (Rhizoma chuanxiong; CX) and roots of Angelica sinensisUsing the HPLC/DAD/ESI/MS method, the qualitative and quantitative analysis of senkyunolide A (SA) in the rhizomes of Ligusticum chuanxiong (Rhizoma chuanxiong; CX) and roots of Angelica sinensis (DG) was established. As a result, it was found that SA is a characteristic standard compound for the quality evaluation and chemical differentiation between CX and DG. Methanol was chosen in the preparation of standard solutions and extraction of samples based on the stability data. The identity of SA in CX and DG was unambiguously determined based on the quasimolecular ions in ESI-MS. A comprehensive validation of the method, including sensitivity, linearity, reproducibility and recovery, was conducted using the optimized chromatographic conditions. The linear calibration curve was acquired with R2>0.999 and limit of detection (S/N=3) was estimated to be 12.5 mug/g. The reproducibility was evaluated by repeated sample injection and replicated analysis of samples with the relative standard deviation (RSD) value found within 0.68%. The recovery rates of SA varied within the range of 96.91-101.50% with RSD less than 2.38%. In the present work, the contents of SA were quantified within 3.94-9.14 mg/g and 0.108-0.588 mg/g for 12 batches each of CX and DG. The results demonstrated that SA is a useful standard compound for the quality evaluation and chemical differentiation between CX and DG. The analytical procedure is precise and reproducible and thus suitable for the analysis of a large number of samples.

• Highly accurate nephelometric titrimetry.

  Authors: Xiancheng Zhan, Chengrong Li, Zhiyi Li, Xiucen Yang, Shuguang Zhong, Tao Yi

  Journal of pharmaceutical sciences. 03/2004; 93(2):441-8.

  A method that accurately indicates the end-point of precipitation reactions by the measurement of the relative intensity of the scattered light in the titrate is presented. A new nephelometricA method that accurately indicates the end-point of precipitation reactions by the measurement of the relative intensity of the scattered light in the titrate is presented. A new nephelometric titrator with an internal nephelometric sensor has been devised. The work of the titrator including the sensor and change in the turbidity of the titrate and intensity of the scattered light are described. The accuracy of the nephelometric titrimetry is discussed theoretically. The titration of NaCl with AgNO(3) serves as a model. A relative error as well as deviation is within 0.2% under the experimental conditions. The applicability of the titrimetry in pharmaceutical analyses, for example, phenytoin sodium and procaine hydrochloride, is generally illustrated.

• [Highly-accurate nephelometric titrimetry]

  Authors: Cheng-rong Li, Xian-Cheng Zhan, Tao Yi, Zhi-yi Li, Xiu-cen Yang, Liang Wang

  Yao xue xue bao = Acta pharmaceutica Sinica. 08/2003; 38(7):537-42.

  AIM: To indicate the titration end-point of precipitation reaction by measuring the relative intensity of the scattered light in the titrate for use in pharmaceutical analysis. METHODS: A visibleAIM: To indicate the titration end-point of precipitation reaction by measuring the relative intensity of the scattered light in the titrate for use in pharmaceutical analysis. METHODS: A visible light-emitting diode (LED) was used as a light source and a photodiode was used as the optical detector. Light on the detector creates an electric current through the diode. With the addition of the titrant, the titrate became turbid and the intensity of the scattered light in the solution increased gradually. If the precipitation reaction proceeded the completion and the solubility of the precipitate was small enough, the intensity of the scattered light will reach maximum at the stoichiometric point; thus, the titration end-point can be indicated. The accuracy of nephelometric titrimetry was discussed theoretically and the titration of NaCl with AgNO3 was used as a model. To demonstrate the applicability of the new titrimetry in pharmaceutical analysis, phenytoin sodium and procaine hydrochloride were titrated with AgNO3 and NaOH solutions, respectively. RESULTS: With our new titrator and nephelometric sensor, the accuracy and precision of our new titrimetry can be better than 0.2% under suitable conditions. CONCLUSION: This new titrimetry can be used for pharmaceutical analysis.

• Simultaneous qualitative and quantitative analyses of the major constituents in the rhizome of Ligusticum Chuanxiong using HPLC-DAD-MS.

  Authors: Tao Yi, Kelvin Sze-Yin Leung, Guang-Hua Lu, Kelvin C. Chan, Hao Zhang

  An HPLC-DAD-MS method was developed for the qualitative and quantitative analysis of the major constituents in Chuanxiong (the dried rhizome of Ligusticum chuanxiong Hort). Twenty compounds includingAn HPLC-DAD-MS method was developed for the qualitative and quantitative analysis of the major constituents in Chuanxiong (the dried rhizome of Ligusticum chuanxiong Hort). Twenty compounds including phenolic constituents, alkylphthalides and phthalide dimers were identified using online ESI-MS and comparisons with literature data and standard compounds, and six of them were quantified by HPLC-DAD simultaneously. A comprehensive validation of the method including sensitivity, linearity, repeatability and recovery was conducted. The linear regressions were acquired with R(2) > 0.99 and limit of detection (LOD, S/N = 3) values were between 1.5 and 2.5 ng. The repeatability was evaluated by intra- and inter-day assays, and relative standard deviation (RSD) values were reported within 1.87%. The recovery studies for the quantified compounds were observed in the range of 96.36-102.37% with RSD values less than 2.63%. These phenolic constituents and alkylphthalides, the major constituents in Chuanxiong, are generally regarded as the index for the quality assessment of this herb. The overall procedure is accurate and reproducible, which is considered suitable for the qualitative and quantitative analyses of a large number of Chuanxiong samples.

• Identification and determination of the major constituents in traditional Chinese medicinal plant Polygonum multiflorum thunb by HPLC coupled with PAD and ESI/MS.

  Authors: Tao Yi, Kelvin S Y Leung, Guang-Hua Lu, Hao Zhang, Kelvin Chan

  Phytochemical analysis : PCA. 18(3):181-7.

  An HPLC-PAD-MS method has been developed for the qualitative and quantitative analysis of the major chemical constituents in Polygonum multiflorum Thunb. Chromatographic separation was conducted onAn HPLC-PAD-MS method has been developed for the qualitative and quantitative analysis of the major chemical constituents in Polygonum multiflorum Thunb. Chromatographic separation was conducted on an Alltima C18 column using water:acetonitrile:acetic acid as the mobile phase. Altogether nine compounds of various classes, including stilbene glucosides, anthraquinone glucosides and anthraquinone derivates, were identified by online ESI/MS. Their identities were ascertained by comparison with data derived from the literature and/or standard compounds. Five components were quantified by HPLC-PAD and the method was fully validated. All the linear regressions were acquired with R2 > 0.99 and the quantification limits (with a signal-to-noise ratio of 3) ranged from 0.63 and 1.57 ng. Repeatability was evaluated by intra- and inter-day assays and RSD value was within 2.47%. Recovery studies for the quantified compounds were found to be within the range 96.32-102.53% with RSD less than 2.35%. The overall procedure is rapid and reproducible and is considered suitable for qualitative and quantitative analysis of a large number of samples.