Author

Lifeng Li

Year of Award

8-16-2019

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

School of Chinese Medicine.

Principal Supervisor

Han, Simon Q. B.

Keywords

Analysis ; Medicine, Chinese ; Polysaccharides

Language

English

Abstract

Polysaccharides are abundant in Chinese medicines (CMs) and play important roles in these materials' bioactivities. But at present, the polysaccharides are seldom incorporated into the quality assessment system of CMs. One of the big bottlenecks encountered is the difficulties in quality analysis due to their large molecular mass, diverse and complex chemical structure. Hereby, in current study, evidence and improved analysis approaches related to polysaccharides quality are proposed by employing several CMs as objectives. Firstly, Lingzhi (Ganoderma lucidum and G. sinense) was used to provide evidence of the importance of polysaccharides quality assessment in CMs. The results showed that the polysaccharides from two species shared the same structural features in terms of mono-/oligo-saccharide profiles, molecular size, sugar linkages, and IR/NMR spectra. And these polysaccharides showed no obvious difference in antitumor/immunomodulating activities and mechanism related to the activation of some proteins via TLR-4 related signaling pathway and gut-microbiota modulatory effects. Following that, to solve the problems existed in qualitative and quantitative analysis of polysaccharide in CMs, a fluorescence-labeled oligosaccharide-marker approach was raised accordingly based on LC-DAD-qTOF -MS analysis. Taking Danggui Buxue Tang (DBT) as an example, the result showed that 1) selected oligosaccharide marker generated by mild hydrolyzation and ABEE-labeling could powerfully differentiate individual herb polysaccharides. 2) good linearity was established between the identified oligosaccharide-markers and individual polysaccharides (r≥0.99). 3) the established method had satisfactory repeatability (RSD≤8.4%), recovery (≥80%) and sensitivity in polysaccharide quantitation in DBT. Finally, a polysaccharide quality analysis was conducted to dynamically trace the absorption, dynamic distribution and degradation of orally-dosed DOP (a marker polysaccharide from Dendrobium officinale) in mice and in vitro using near-infrared fluorescence imaging and chromatographic analysis. The results indicate that DOP was not absorbed and digested but were quickly degraded to short-chain fatty acids in the large intestine where gut microbiota existed. The interaction could be associated with DOP's suppression of 4T1 tumor growth in mice. In conclusion, by these studies, the importance of bioactive polysaccharides in quality assessment of CMs was confirmed. The mentioned predicaments in quality analysis of polysaccharides were greatly improved whether in CMs or complex biological matrix in vivo and in vitro. All the approaches proposed will contribute to other polysaccharides or polysaccharide-dominated CMs' analysis.

Comments

Principal supervisor: Doctor Han, Simon Q. B ; Thesis submitted to the School of Chinese Medicine ; Thesis (Ph.D.)--Hong Kong Baptist University, 2019.

Bibliography

Includes bibliographical references (pages 162-175).

Available for download on Sunday, October 17, 2021



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