Hongwei Luan

Chemotaxonomic study of medicinal Taxus species with fingerprint and multivariate analysis.

Species delimitation in Taxus has been controversial and it is very difficult to distinguish yew materials by their morphological characters. In this paper, a valid HPLC fingerprinting method coupled with multivariate analysis was used to define a framework for Taxus species identification and classification. Fingerprint-based similarity was employed for a chemotaxonomic study by hierarchical clustering analysis (HCA) and principal component analysis (PCA). Based on the PCA loadings, twelve chemical constituents were selected as chemotaxonomic markers which can be used to establish a more practical classification. Finally, eight studied species could be divided into six well-supported groups and most samples can be assigned to the correct species. Additionally, twelve markers were tentatively identified by LC/MS.

Profiling of yew hair roots from various species using ultra‐performance liquid chromatography/electrospray ionization mass spectrometry

An efficient and sensitive profiling approach to complex yew samples was developed using ultra-performance liquid chromatography/electrospray ionization mass spectrometry (UPLC/ESI-MS). The UPLC-based method displayed short analytical time and improved peak capability, as well as high sensitivity. The appropriate in-source collision-induced dissociation (CID) energy was employed to produce informative characteristic ions which could be used for stereochemical and sub-structural assignment of yew constituents. The method was successfully applied in the rapid screening of yew hair roots from various species, and 53 constituents including 47 taxoids were detected from partially purified root extract. Notably, C-7 hydroxytaxane stereoisomers could be identified based on their different fragment ions under the optimal profiling conditions. It was also observed that hair roots from different Taxus species exhibited nearly identical chemical distribution, indicating they had similar metabolic frameworks. Additionally, Taxus root resources also display benign medicinal perspective because they have relatively simple chemical profiles and possess high yields of valuable taxanes such as paclitaxel, cephalomannine, 10-deacetylpaclitaxel and 7-xylosyltaxanes.

Functional and structural properties of a novel cellulosome-like multienzyme complex: efficient glycoside hydrolysis of water-insoluble 7-xylosyl-10-deacetylpaclitaxel.

Cellulosome is a kind of multienzyme complex that displays high activity, selectivity, and stability. Here, we report a novel, non-cellulolytic, cellulosome-like multienzyme complex that produced by the Cellulosimicrobium cellulans wild-type strain F16 isolated from soil microflora. This multienzyme complex, with excellent catalytic efficiency of kcat 13.2 s−1 to remove the C-7 xylosyl group from 7-xylosyl-10-deacetylpaclitaxel (10-DAXP), has an outstanding tolerance against organic solvents and an excellent general stability, with the long half-life of 214 hours. This cellulosome-like multienzyme complex has a novel structure distinct from the well-documented ones. The key catalytic subunit responsible for the β-xylosidase activity against 10-DAXP is identified to be a novel protein, indicating a new glycoside hydrolase (GH) family. The pioneering work described here offers a novel nanoscale biocatalyst for the production of biofuels and chemicals from renewable plant-based natural resources.

Rapid Qualitative and Quantitative Determination of Seven Valuable Taxanes from Various Taxus Species by UFLC‐ESI‐MS and UFLC‐DAD

The distribution and level of yew constituents vary with species and tissues. In this study, a rapid and valid method incorporating ultra-fast liquid chromatography (UFLC) with MS and UV detection was developed for simultaneous determination of paclitaxel and its six semisynthesis precursors in needles and hair roots from various Taxus species. All target analytes could be identified by comparing their retention times as well as UV and MS spectra with authentic standards, while seven valuable taxanes in botanical samples can be rapidly determined by UFLC-DAD with excellent sensitivity. Analysis of more than one hundred yew samples from nine species showed significant variations in distribution and content of seven evaluated taxanes. Thus, different developmental schemes should be used for better utilization of various yew resources.

Acceptor Specificity and Transfer Efficiency of a β-Glycosidase from the China White Jade Snail

The acceptor specificity and transfer potential of a β-D-glycosidase (G I), which had been purified from the China white jade snail, were further investigated by using various sugars as acceptors. G I had broad monosaccharide acceptor specificity for its transglycosylation activity. More specifically, it efficiently catalyzed the transfer of the β-D-fucosyl, β-D-glucosyl or β-D-galactosyl moiety from the corresponding p-nitrophenyl-β-D-glycopyranosides to various monosaccharides. The transfucosylation efficiency of G I was studied by using p-nitrophenyl-β-D-fucopyranoside (pNPFuc) as the donor and glucose and xylose as the acceptors. The yields under conditions of non-initial velocity were 88% for glucose and 93% for xylose. The transfer product with glucose as the acceptor was isolated and identified as β-fucosyl-1,6-glucose by an NMR analysis. The data from these analyses indicate that G I had broad acceptor specificity and high efficiency for transglycosylation. These uncommon properties of G I could make it a valuable biocatalyst for the synthesis of various disaccharides.