Phytochemical Reinvestigation Of The Roots Of Eurycoma Longifolia And Development Of A LC-MS Method For Qualitative And Quantitative Analyses Of Their Major Constituents
| dc.contributor.author | Teh, Chin Hoe | |
| dc.date.accessioned | 2017-02-23T01:25:35Z | |
| dc.date.available | 2017-02-23T01:25:35Z | |
| dc.date.issued | 2010-07 | |
| dc.description.abstract | The 30 % methanol fraction eluted from resin chromatography of methanol extract of the roots of Eurycoma longifolia Jack showed good antimalarial activity (Wemsdorfer et al., 2009). Sequential partition of this fraction, followed by chromatographic separations and recrystallization afforded ten chemical constituents. Of these, one was a novel C19 longilactone-type quassinoid, named 2,3-dehydro-4ahydroxylongilactone (117), possessing an unsubstitituted vinyl function and a C-4 methyl group of P---configuration in ring A. Eurycomanone (3) and 13,21- dihydroeurycomanone (11), the two known quassinoids, were crystallized as novel crystal structures with a space group of orthorhombic P212121 and monoclinic P21, respectively. Meanwhile, the two known non-quassinoids, scopolin (118) and 2,3- dihydroxy-1-(4'-hydroxy-3'-methoxyphenyl)propan-1-one (119) were isolated from this plant for the first time. All structures were characterized by spectroscopic analysis (lD and 2D NMR experiments, HRMS, UV, IR and optical rotation) and by comparison with known spectroscopic data. Extensive mass spectrometry optimization was performed in order to achieve the maximum sensitivity for the target analyte. Comparison between electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) was performed on eurycomanone (3), eurycomanol (4), 13,21-dihydroeurycomanone (11 ), 13 a(21 )-epoxyeurycomanone (15), eurycomanol-2-0-/i-D-glucopyranoside (9), and scopolin (118) using automated flow injection analysis (PIA). The effect of eluent composition (contained methanol or acetonitrile) and acidic modifiers (acetic acid, formic acid and trifluoroacetic acid) on the ionization efficiency of the aforementioned standards were also investigated. Subsequently, the effects of nebulizer pressure, dry gas flow, dry gas temperature and capillary voltage on the sensitivity of the six compounds in positive ion mode of ESI were measured and compared. Fragmentation of analytes for subsequent selective Multiple Reaction Monitoring (MRM) analysis was investigated by varying the capillary exit offset voltage and fragmentation amplitude in positive mode of ESI. The detection limits (LODs) were determined in isolation mode (selected ion monitoring, SIM) for the analytes by LC-ESI-MS positive ion mode in order to investigate the sensitivity of the assay developed. The LOD values were ranged between 0.03-0.1 Jlg mL-1 while the intra-day and inter-day precisions, expressed in relative standard deviations, were less than 5.72 %and 4.82 %, respectively. Based on the optimal mass spectrometry parameters established, a new analytical method using HPLC with ESI-MS detection was successfully applied for the simultaneous determination of the bioactive phytochemical markers of the various batches of standardised extracts of E. longifolia developed for antimalarial treatment. From the samples analyzed, eurycomanone (3), eurycomanol ( 4) and eurycomanol-2-0-.B-Dglycopyranoside (9) were the main quassinoids in the bioactive extracts, whereas 13,21-dihydroeurycomanone (11) and 13a(21)-epoxyeurycomanone (15) existed in the comparable amount, were present in much lower quantity. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/3772 | |
| dc.language.iso | en | en_US |
| dc.publisher | Universiti Sains Malaysia | en_US |
| dc.subject | The roots of Eurycoma longifolia Jack showed | en_US |
| dc.subject | good antimalarial activity. | en_US |
| dc.title | Phytochemical Reinvestigation Of The Roots Of Eurycoma Longifolia And Development Of A LC-MS Method For Qualitative And Quantitative Analyses Of Their Major Constituents | en_US |
| dc.type | Thesis | en_US |
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