Sparse Semiparametric Nonlinear Model with Application to Chromatographic Fingerprints.

Traditional Chinese herbal medications (TCHMs) are comprised of a multitude of compounds and the identification of their active composition is an important area of research. Chromatography provides a visual representation of a TCHM sample's composition by outputting a curve characterized by spikes corresponding to compounds in the sample. Across different experimental conditions, the location of the spikes can be shifted, preventing direct comparison of curves and forcing compound identification to be possible only within each experiment. In this article we propose a sparse semiparametric nonlinear modeling framework for the establishment of a standardized chromatographic fingerprint. Data-driven basis expansion is used to model the common shape of the curves while a parametric time warping function registers across individual curves. Penalized weighted least squares with the adaptive lasso penalty provides a unified criterion for registration, model selection, and estimation. Furthermore, the adaptive lasso estimators possess attractive sampling properties. A back-fitting algorithm is proposed for estimation. Performance is assessed through simulation and we apply the model to chromatographic data of rhubarb collected from different experimental conditions and establish a standardized fingerprint as a first step in TCHM research.

[UPLC fingerprint of rhei radix et rhizoma from different habitats].

OBJECTIVE: To establish the UPLC fingerprint of Rhei Radix et Rhizoma and reference crude drugs, analyze the characteristics among fingerprints of three species of reference crude drugs and the common components of Rhei Radix et Rhizoma, and compare the application of different analysis methods. METHODS: UPLC procedure was performed on ACQUITY BEH C18 chromatographic column with mobile phase consisted of water (contained 0.1% phosphoric acid)-acetonitrile (gradient elution) at a flow rate of 0.21 mL/min. Detection wavelength was set at 260 nm and the column temperature was set at 30 degrees C. Fingerprints were analyzed by similarity evaluation, cluster analysis and principal component analysis. RESULTS: There were obvious characteristics among fingerprints of three species of reference crude drugs, 19 common chromatographic peaks were obtained from Rhei Radix et Rhizoma and 14 peaks were identified according to standard reference substances and by HPLC-MS. The cluster analysis and similarity evaluation showed the same result that 21 batches of sample were grouped into 5 categories and the result had no direct correlation with the botanical species. Both the contents of4 important ingredients suggested by principal component analysis and the whole fingerprint analysis were necessary in quality evaluation of Rhei Radix et Rhizoma. There was certain limitation in quality evaluation of multiple sources drug which analysis by similarity evaluation and cluster analysis. CONCLUSION: The method with good reproducibility and separation saves time and solvent, it can be used in identification of three species of reference crude drugs but can not be used in species identification of commercial Rhei Radix et Rhizoma.

[Study on the chemical constituents from Melicope ptelefolia].

OBJECTIVE: To study the chemical constituents from Melicope ptelefolia. METHODS: Several chromatographic methods were applied to isolate and purify compounds. Their structures were identified on the basis of physicochemical properties and spectroscopic data. RESULTS: Seven compounds were isolated and elucidated as n-octadecanyl palmitate (I), beta-sitosterol (II), palmitic acid (III), 3, 5,3'-trihydroxy-8,4'-dimethoxy-7-(3-methylbut-2-enyloxy) flavone (IV), daucosterol (V), salylic acid (VI), kaempferol-3-O-alpha-D-arabinpyranoside (VII). CONCLUSION: Compound VII is isolated from the genus for the first time, Compounds V and VI are isolated from Melicope ptelefolia for the first time.