Bioassay-guided isolation of free radical scavenging and antioxidative flavonoid from Zingiber ottensii (zingiberaceae)

Naransa Limpot, (2006) Bioassay-guided isolation of free radical scavenging and antioxidative flavonoid from Zingiber ottensii (zingiberaceae). Masters thesis, Universiti Malaysia Sabah.


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Bioassay-guided fractionation by 2, 2-diphenyl-l-picrylhydrazyl has been conducted for rhizomes and leaves of Zingiber ottensii to isolate and elucidate the bioactive compound that possess free radical scavenging and antioxidative activities present in the methanol extract. The isolated active compound was identified by means of spectroscopic methods as quercetin-3-0-rhamnosylglucoside. The total content of the active compound in equivalence to quercetin was also quantified and found that the quercetin content was more in rhizomes compared to the leaves. The rhizomes were also found to contain sugars which contributed 60% of the dry weight and was identified by using Bial's Reagent as hexoses and pentoses. This finding can contribute towards the novel study in gingers since there is a void in the present literature on the subject. The autoxidation of fJ-carotene was also tested in effort to investigate the ability of the isolated compound toward inhibition of lipid peroxidation. It was found that this compound was as active as the synthetic antioxidant, BHT, and was more active than the corresponding quercetin aglycone. Eventhough, quercetin has been known as an excellent radical scavenger and inhibit lipid peroxidation, this is the first time this compound was detected in Z. ottensii.

Item Type: Thesis (Masters)
Uncontrolled Keywords: bioassay-guided, leaves of Zingiber, bioactive, quercetin, autoxidation
Subjects: Q Science > QK Botany
Divisions: SCHOOL > Institute for Tropical Biology and Conservation
Date Deposited: 21 Aug 2013 07:24
Last Modified: 11 Oct 2017 09:12

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