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Polyphenols from Dendrobium Pompadour and antioxidant capacity analysis of polyphenols
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Type
Thesis
Author
Kong, Jinming
Supervisor
Chia, Lian Sai
Abstract
Flavonoids, a group of secondary plant metabolites occurring widely throughout the plant kingdom, have been reported to possess anti-inflammatory, antibacterial, antiviral, antiallergenic, and antitumor activities. Flavonoids have also been found to possess antioxidant and antiradical properties. It is believed that the biological effects of flavonoids come from their antioxidant properties, including their protection against iron-induced free radical reactions.
Orchidaceae, the biggest monocot family with 30,000 species and 750 genera, are rich in flavonoids, have a long history as medicine, but have limited studies. In our research, we chose some kinds of orchid flowers and isolated ten flavonoids and two anthocyanins from flowers of one type of orchid Dendrobium Pompadour.
In the first chapter, the history of herbal medicine, the medicinal application of orchids, the most recent research advances in orchids and the development of phytochemical studies in Singapore have been reviewed.
In Chapter 2, the main technological advances of flavonoid and anthocyanin studies are reviewed. It includes the development of methodology and the interaction between anthocyanins and surrounding molecules, either in intermolecular form or intramolecular form, such as the structural transformation of anthocyanins in water and copigmentation in either way.
In Chapter 3, the antioxidant capacities of crude orchid flower extracts were investigated by ESR method. Dendrobium Pompadour has the highest antioxidant activity against ABTS radical among the selected orchid flowers, both the aqueous and organic phases of its methanol extracts show high antioxidant activities. The metal analytical results of these flowers show that all those samples have higher Mg content but lower Fe content.
Chapter 4 deals with the isolation and characterisation of the flower of Dendrobium Pompadour, two acylated anthocyanins and ten flavonoids were obtained, among them quercetin 3-[x"-ferulylrhamnosyl (1→ 6) glucoside-7-glucoside was identified for the first time. The use of capillary zone electrophoresis in the flavonoid analysis was investigated in Chapter 5, a simple and fast capillary zone electrophoresis method provided satisfactory resolution of selected flavonoid standards. Its results were compared with those of high performance liquid chromatography method. Finally, the conclusions and the suggestions for future study are listed in Chapter 6.
Orchidaceae, the biggest monocot family with 30,000 species and 750 genera, are rich in flavonoids, have a long history as medicine, but have limited studies. In our research, we chose some kinds of orchid flowers and isolated ten flavonoids and two anthocyanins from flowers of one type of orchid Dendrobium Pompadour.
In the first chapter, the history of herbal medicine, the medicinal application of orchids, the most recent research advances in orchids and the development of phytochemical studies in Singapore have been reviewed.
In Chapter 2, the main technological advances of flavonoid and anthocyanin studies are reviewed. It includes the development of methodology and the interaction between anthocyanins and surrounding molecules, either in intermolecular form or intramolecular form, such as the structural transformation of anthocyanins in water and copigmentation in either way.
In Chapter 3, the antioxidant capacities of crude orchid flower extracts were investigated by ESR method. Dendrobium Pompadour has the highest antioxidant activity against ABTS radical among the selected orchid flowers, both the aqueous and organic phases of its methanol extracts show high antioxidant activities. The metal analytical results of these flowers show that all those samples have higher Mg content but lower Fe content.
Chapter 4 deals with the isolation and characterisation of the flower of Dendrobium Pompadour, two acylated anthocyanins and ten flavonoids were obtained, among them quercetin 3-[x"-ferulylrhamnosyl (1→ 6) glucoside-7-glucoside was identified for the first time. The use of capillary zone electrophoresis in the flavonoid analysis was investigated in Chapter 5, a simple and fast capillary zone electrophoresis method provided satisfactory resolution of selected flavonoid standards. Its results were compared with those of high performance liquid chromatography method. Finally, the conclusions and the suggestions for future study are listed in Chapter 6.
Date Issued
2001
Call Number
QK898.F5 Kon
Date Submitted
2001