Phytochemical and biological studies of Tibouchina Semidecandra L

Phytochemical studies on Tibouchina semidecandra L., previously known as T. urvilleana have resulted in the isolation of nine pure compounds comprising of one flavonol, three flavonol glycosides, two plant sterols, one fatty acid, an ester and one ellagic acid glycoside. Five compounds have been suc...

Full description

Saved in:

Bibliographic Details
Main Author:	Rezali, Mohd. Fazlin
Format:	Thesis
Language:	English
Published:	2008
Subjects:	Q Science (General)
Online Access:	http://eprints.utm.my/id/eprint/33695/1/MohdFazlinBinRezaliMFS2008.pdf
Tags:	Add Tag No Tags, Be the first to tag this record!

id	my-utm-ep.33695
record_format	uketd_dc
spelling	my-utm-ep.336952021-06-01T01:29:34Z Phytochemical and biological studies of Tibouchina Semidecandra L 2008 Rezali, Mohd. Fazlin Q Science (General) Phytochemical studies on Tibouchina semidecandra L., previously known as T. urvilleana have resulted in the isolation of nine pure compounds comprising of one flavonol, three flavonol glycosides, two plant sterols, one fatty acid, an ester and one ellagic acid glycoside. Five compounds have been successfully isolated from the leaves, i.e quercetin, β-sitosterol-O-β-D-glucopyranoside, quercetin 3-O-α-L-(2′′-O-acetyl) arabinofuranoside, avicularin and quercitrin. Three compounds identified as oleic acid, eicosanyl trans-p-coumarate and 23-ethyl-cholest-5-en-3-ol have been isolated from the roots. The stem barks gave one ellagitannin, identified as 3,3′-O-dimethyl ellagic acid 4-O-α-L-rhamnopyranoside. Methylation of quercetin gave quercetin tetramethyl ether, while acetylation of quercetin yielded quercetin tetraacetoxyl acetate. The structures of all compounds were established based on spectral studies using nuclear magnetic resonance, infrared and ultraviolet spectroscopies as well as mass spectrometry. Evaluation of the antioxidative activity on the crude extracts and pure compounds by electron spin resonance (ESR) and ultraviolet-visible (UV-vis) spectrophotometric assays showed that the pure isolated flavonoids and the EtOAc extract of the leaves possessed strong antioxidative capabilities. Quercetin was found to be the most active as radical scavenger in DPPH-UV and ESR methods with SC50 of 0.7 μM ± 1.4 and 0.7 μM ± 0.6, respectively in the antioxidant assay. A combination of quercetin and quercitrin was tested for synergistic anti-oxidative capacity. However, there was no significant improvement observed. The antimicrobial assay on the crude extracts and pure compounds were carried out against the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and the Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli. However, no significant activity was observed. Quercetin and quercetin tetraacetoxyl acetate exhibited strong antityrosinase agent with percent inhibition of 95.0% and 93.4% respectively, equivalent to the positive control, kojic acid in the tyrosinase enzyme assay. 2008 Thesis http://eprints.utm.my/id/eprint/33695/ http://eprints.utm.my/id/eprint/33695/1/MohdFazlinBinRezaliMFS2008.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:75140?queryType=vitalDismax&query=Phytochemical+and+biological+studies+of+Tibouchina+Semidecandra+L&public=true masters Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	Q Science (General)
spellingShingle	Q Science (General) Rezali, Mohd. Fazlin Phytochemical and biological studies of Tibouchina Semidecandra L
description	Phytochemical studies on Tibouchina semidecandra L., previously known as T. urvilleana have resulted in the isolation of nine pure compounds comprising of one flavonol, three flavonol glycosides, two plant sterols, one fatty acid, an ester and one ellagic acid glycoside. Five compounds have been successfully isolated from the leaves, i.e quercetin, β-sitosterol-O-β-D-glucopyranoside, quercetin 3-O-α-L-(2′′-O-acetyl) arabinofuranoside, avicularin and quercitrin. Three compounds identified as oleic acid, eicosanyl trans-p-coumarate and 23-ethyl-cholest-5-en-3-ol have been isolated from the roots. The stem barks gave one ellagitannin, identified as 3,3′-O-dimethyl ellagic acid 4-O-α-L-rhamnopyranoside. Methylation of quercetin gave quercetin tetramethyl ether, while acetylation of quercetin yielded quercetin tetraacetoxyl acetate. The structures of all compounds were established based on spectral studies using nuclear magnetic resonance, infrared and ultraviolet spectroscopies as well as mass spectrometry. Evaluation of the antioxidative activity on the crude extracts and pure compounds by electron spin resonance (ESR) and ultraviolet-visible (UV-vis) spectrophotometric assays showed that the pure isolated flavonoids and the EtOAc extract of the leaves possessed strong antioxidative capabilities. Quercetin was found to be the most active as radical scavenger in DPPH-UV and ESR methods with SC50 of 0.7 μM ± 1.4 and 0.7 μM ± 0.6, respectively in the antioxidant assay. A combination of quercetin and quercitrin was tested for synergistic anti-oxidative capacity. However, there was no significant improvement observed. The antimicrobial assay on the crude extracts and pure compounds were carried out against the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and the Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli. However, no significant activity was observed. Quercetin and quercetin tetraacetoxyl acetate exhibited strong antityrosinase agent with percent inhibition of 95.0% and 93.4% respectively, equivalent to the positive control, kojic acid in the tyrosinase enzyme assay.
format	Thesis
qualification_level	Master's degree
author	Rezali, Mohd. Fazlin
author_facet	Rezali, Mohd. Fazlin
author_sort	Rezali, Mohd. Fazlin
title	Phytochemical and biological studies of Tibouchina Semidecandra L
title_short	Phytochemical and biological studies of Tibouchina Semidecandra L
title_full	Phytochemical and biological studies of Tibouchina Semidecandra L
title_fullStr	Phytochemical and biological studies of Tibouchina Semidecandra L
title_full_unstemmed	Phytochemical and biological studies of Tibouchina Semidecandra L
title_sort	phytochemical and biological studies of tibouchina semidecandra l
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2008
url	http://eprints.utm.my/id/eprint/33695/1/MohdFazlinBinRezaliMFS2008.pdf
_version_	1747816162544058368

Phytochemical and biological studies of Tibouchina Semidecandra L

Similar Items