Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliographical references.

The polyphenolic pigments of black tea include the theaflavins (TF), the flavonol glycosides (FG) and a group of uncharacterised brown pigments referred to as thearubigins (TR). The TR are shown to be a complex, heterogeneous group of compounds, the majority of which are unresolvable by reverse phase HPLC. Fractionation procedures have been modified, developed, combined and applied to black tea liquor, to improve the separation of black tea components and to allow fractions of less complexity be obtained. A degree of resolution has been achieved for TR fractions, unresolvable with reverse phase HPLC, using size exclusion HPLC. Calibration of the column suggested there may be little material above 2,000 daltons associated with the TR. Two heterogeneous TR fractions have been subjected to Porter's autoxidative assay for proanthocyanidins. The resulting solutions were analysed by reverse phase HPLC and shown to contain proanthocyanidins (9.4 and 16.1 %) and galloyl ester (7.1 and 7.4 %), some 73 and 84 % remains uncharacterised. A novel group of yellow pigments has been isolated for which the name theacitrins (TC) has been proposed. Data are presented that suggest the TC are possibly derived from the TF by oxidative opening of the dihydroxybenzene ring associated with the benztropolone structure. The contribution of the phenolic pigments to tea cream was investigated using reversed phase HPLC and found to be ? 86 % TR, 12 % TF and 2 % FG. Evidence is also presented for a synergistic interaction between TF and TR during cream formation. A method has been developed, using caffeine precipitation, for the isolation of TR material that is free from TF and FG Tea pigments have been stored in aqueous solutions to evaluate their potential for use as commercial colourants. The TF and TC were found to possess poor stability. The FG exhibited greater stability but possess low tinctoral power and poor water solubility. Many of the stability trials exhibited a darkening of colour associated with an increase in unresolvable TR material. Storage of an aqueous solution of a TF enriched fraction at 37 °C resulted in the production of unresolvable (TR-like) material. This material was found to possess molecular weights in excess of 2,000, indicating polymerisation. Evidence is presented to suggest the involvement of galloyl groups in the formation of non-hydrolysable bonds within this polymeric material.

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Poon Yin-tat. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 101-111). / ACKNOWLEDGEMENTS --- p.I / ABSTRACT --- p.II / LIST OF ABBREVIATIONS --- p.IV / TABLE OF CONTENTS --- p.V / Chapter CHAPTER 1: --- INTRODUCTION --- p.1 / Chapter CHAPTER 2: --- PURIFICATION OF α- AND β-MOMORCHARINS --- p.26 / Chapter CHAPTER 3: --- N-GLYCOSIDASE ACTIVITY OF α- AND β-MOMORCHARINS --- p.45 / REFERENCES --- p.101

by Yeung Kwan Wing. / Thesis submitted in: 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 68-73). / Abstracts in English and Chinese. / Contents --- p.i / Acknowledgement --- p.ii / Abstract --- p.iii / Abbreviation --- p.v / Chapter 1. --- Introduction --- p.1 / Chapter 1-1 --- Background --- p.1 / Chapter 1-2 --- Sharpless Epoxidation --- p.2 / Chapter 1-3 --- Mn-Salen Complexes for Epoxidation --- p.4 / Chapter 1-4 --- Oxaziridinium Salts --- p.6 / Chapter 1-5 --- Dioxiranes --- p.7 / Chapter 1-6 --- Asymmetric Epoxidation by Dioxirane --- p.11 / Chapter 2. --- Results and Discussion --- p.28 / Chapter 2-1 --- C-Glycoside Ulose Catalyst derived from L-arabinose --- p.28 / Chapter 2-2 --- Dioxirane epoxidation catalyzed by L-arabino-4-uloses --- p.30 / Chapter 3. --- Experimental Section --- p.51 / Chapter 4. --- References --- p.68 / Chapter 5. --- Appendix --- p.74

The n-butanol extract of aerial parts of Cordyline australis demonstrated antifungal activity. n-Butanol and chloroform extracts of dried or fresh leaves of C. australis afforded a steroidal glycoside, which was identified as 5α-spirost-25(27)-en-3β-ol 3-O{O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside}, saponin 1. This spirostanol glycoside showed strong antifungal activity towards Trichophyton mentagrophytes and some aspecific activity and cytotoxicity against MRC5 cell. The chloroform extract of fresh leaves of C. australis yielded a second new spirostanol glycoside which was identified as 5α-spirost-25(27)-ene-1β,3β-diol 1-{O-α-L-rhamnopyranosyl-(1→2)-β-D-fucopyranoside}, saponin 2. The n-butanol extracts of senescent leaves of C. australis afforded a third new spirostanol glycoside that was identified as 5α-spirost-25(27)-ene-1β,3β-diol 1-{O-β-D- fucopyranoside, saponin 3. A mixture of two isomeric flavonoid glycosides was isolated from dried leaves of C. australis and shown to be a ca 1:1 mixture of isorhamnetin-3-O-{O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside}, 4 and isorhamnetin-3-O-{O-α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranoside}, 5. Three other known steroidal glycosides, β-sitosterol glucoside, 6, prosapogenin A of dioscin, 7, and trillin, 8 were also isolated from the leaves of C. australis. The n-butanol extract of dried stems of C. australis afforded (25S)-5α-spirostane-1β,3α-diol 1-{O-β-D-glucopyranoside}, 9. This spirostanol glycoside showed moderate cytotoxicity against Herpes simplex type I virus (ATCC VR733) and Polio Virus Type I (Pfiser vaccine strain).

Includes a list of publications co-authored by the author during the preparation of this thesis. Bibliography: leaves 103-111. Studies the links between grape composition, wine composition and wine sensory properties. Developed a new method of measuring glycoside concentration in grapes (glycosyl-glucose assay) and a modified measurement of wine colour density in red wine. These were used to analyse samples of Shiraz grapes and wines from a comprehensive vineyard irrigation trial. Glycosyl-glucose concentrations shows promise for the prediction of wine composition and flavor intensity.