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Study of antioxidant capacity of flavonoids from ginger plants
Author
Shrila Balachandran
Supervisor
Chia, Lian Sai
Abstract
This study is based on the knowledge that the main constituents in the extracts from the ginger plants are flavonoids. In this study, their antioxidant potency was measured by Trolox equivalent antioxidant capacities (TEAC) assay with ultraviolet-visible spectrometry. From the results of the antioxidant capacities of nine pure flavonoids, it was found that quercetin is a more effective antioxidant than other flavonoids such as rutin and kaempferol. The time consuming work of isolating crude extracts (flavonoids) of the selected ginger plants was achieved through step-by-step procedures using five different solvents (water, methanol, acetone, chloroform and hexane). As a result, seventy-two crude solvent extracts from the ginger plants were obtained. The results of the antioxidant capacities of the different fractions from the leaves, flowers and rhizomes of Costus speciosus K. Smith, as well as the rhizomes of the five other ginger plants using TEAC method showed that the methanol fraction had the highest antioxidant capacity, while the lowest one was hexane fraction.
The antioxidant capacity of the different aqueous methanol fractions from the leaves, flowers and rhizomes of Costus speciosus K. Smith as well as the rhizomes of the five other ginger plants were also measured by TEAC method. It was found that generally 80% methanol fraction of the samples has the highest antioxidant capacity. It was also found that most of the crude extracts had higher antioxidant capacities than trolox. Within the crepe ginger plant, the rhizomes had higher antioxidant capacity than its flowers and leaves. The antioxidant capacities of the rhizomes of the six ginger plants using a 80% methanol were also compared. It was found that the rhizomes of Costus speciosus K. Smith had the highest antioxidant capacity, while that of Alpinia hainanensis K. Schumann from the Zingiberaceae family had the lowest.
The antioxidant capacity of the different aqueous methanol fractions from the leaves, flowers and rhizomes of Costus speciosus K. Smith as well as the rhizomes of the five other ginger plants were also measured by TEAC method. It was found that generally 80% methanol fraction of the samples has the highest antioxidant capacity. It was also found that most of the crude extracts had higher antioxidant capacities than trolox. Within the crepe ginger plant, the rhizomes had higher antioxidant capacity than its flowers and leaves. The antioxidant capacities of the rhizomes of the six ginger plants using a 80% methanol were also compared. It was found that the rhizomes of Costus speciosus K. Smith had the highest antioxidant capacity, while that of Alpinia hainanensis K. Schumann from the Zingiberaceae family had the lowest.
Date Issued
2008
Call Number
QK898.F5 Shr
Date Submitted
2008