Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties

Five series of novel bis(thiourea) derivatives 41a-e, 42a-l, 43a-f, 46a-c and 50a-f bearing different pharmacophores have been successfully synthesised via nucleophilic substitution reaction of benzene-1,4-dicarbonyl isothiocyanate intermediate 52 with various amines derivatives. Preparations of...

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Main Author:	Ainaa Nadiah, Abd Halim
Format:	Thesis
Language:	English
Published:	2017
Subjects:	Q Science (General) QD Chemistry QK Botany
Online Access:	http://ir.unimas.my/id/eprint/23866/5/Ainaa%20Nadiah.pdf
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spelling	my-unimas-ir.238662024-02-13T02:27:40Z Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties 2017 Ainaa Nadiah, Abd Halim Q Science (General) QD Chemistry QK Botany Five series of novel bis(thiourea) derivatives 41a-e, 42a-l, 43a-f, 46a-c and 50a-f bearing different pharmacophores have been successfully synthesised via nucleophilic substitution reaction of benzene-1,4-dicarbonyl isothiocyanate intermediate 52 with various amines derivatives. Preparations of 42a-l and 43a-f in acetonitrile at room temperature produced higher yields compared to the reaction in acetone reflux. The structures of all the synthesised compounds were elucidated using elemental CHN analysis, FT-IR, 1H and 13C NMR spectroscopies and corresponded to the proposed molecular structures. The antibacterial activities of the synthesised compounds were evaluated against bacteria Escherichia coli and Staphylococcus aureus, while antioxidant activities were studied employing DPPH assay. In the 1st series of bis(thiourea) (41a-e), 41c bearing phenyl group exhibited excellent antibacterial activities against E. coli with minimum inhibitory concentration (MIC) of 175 ppm. While, antibacterial studies on the 2nd series of bis(thiourea) (42a-l), bearing halogenated anilines at ortho, meta and para positions, demonstrated that halogens at ortho position (42d and 42g) also exhibited excellent activities against E. coli and S. aureus in comparison to the standard ampicillin. The 3rd series of bis(thiourea) (43a-f), bearing methyl and methoxy to the phenyl group at different positions were inactive towards both bacteria. Antibacterial screening on bis(thiourea) bearing long alkyl chains (46a-c) showed 46a and 46b displayed excellent activity against E. coli with MIC of 135 and 145 ppm respectively, while 46c bearing C14 alkyl chain was acted as cutoff point with no antibacterial properties. Bis(thiourea)-azo 50a-f possessing phenolic group were tested for antioxidant activities. paraSubstituted halogens (50c and 50f) demonstrated good antioxidant activity with IC50 of 105.5 ppm and 122 ppm respectively, while ortho-substituted halogen (50d) showed moderate activity with IC50 of 148 ppm in comparison to ascorbic acid as a standard (IC50 = 14.2 ppm). iv The resonance effect of the halogens substituents stabilised the radical intermediate and enhanced the antioxidant activities. The presence of two folds of N-H, C=O and C=S as well as other substituents in the molecular structure of the synthesised compounds played important roles to the enhancement of the biological properties. The ability of these groups to easily protonated under acidic condition and reacted with the carboxyl and phosphate groups of the bacterial surface further enhanced the antibacterial activities. Universiti Malaysia Sarawak, (UNIMAS) 2017 Thesis http://ir.unimas.my/id/eprint/23866/ http://ir.unimas.my/id/eprint/23866/5/Ainaa%20Nadiah.pdf text en validuser phd doctoral Universiti Malaysia Sarawak Faculty of Resource Science & Technology
institution	Universiti Malaysia Sarawak
collection	UNIMAS Institutional Repository
language	English
topic	Q Science (General) QD Chemistry QK Botany
spellingShingle	Q Science (General) QD Chemistry QK Botany Ainaa Nadiah, Abd Halim Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties
description	Five series of novel bis(thiourea) derivatives 41a-e, 42a-l, 43a-f, 46a-c and 50a-f bearing different pharmacophores have been successfully synthesised via nucleophilic substitution reaction of benzene-1,4-dicarbonyl isothiocyanate intermediate 52 with various amines derivatives. Preparations of 42a-l and 43a-f in acetonitrile at room temperature produced higher yields compared to the reaction in acetone reflux. The structures of all the synthesised compounds were elucidated using elemental CHN analysis, FT-IR, 1H and 13C NMR spectroscopies and corresponded to the proposed molecular structures. The antibacterial activities of the synthesised compounds were evaluated against bacteria Escherichia coli and Staphylococcus aureus, while antioxidant activities were studied employing DPPH assay. In the 1st series of bis(thiourea) (41a-e), 41c bearing phenyl group exhibited excellent antibacterial activities against E. coli with minimum inhibitory concentration (MIC) of 175 ppm. While, antibacterial studies on the 2nd series of bis(thiourea) (42a-l), bearing halogenated anilines at ortho, meta and para positions, demonstrated that halogens at ortho position (42d and 42g) also exhibited excellent activities against E. coli and S. aureus in comparison to the standard ampicillin. The 3rd series of bis(thiourea) (43a-f), bearing methyl and methoxy to the phenyl group at different positions were inactive towards both bacteria. Antibacterial screening on bis(thiourea) bearing long alkyl chains (46a-c) showed 46a and 46b displayed excellent activity against E. coli with MIC of 135 and 145 ppm respectively, while 46c bearing C14 alkyl chain was acted as cutoff point with no antibacterial properties. Bis(thiourea)-azo 50a-f possessing phenolic group were tested for antioxidant activities. paraSubstituted halogens (50c and 50f) demonstrated good antioxidant activity with IC50 of 105.5 ppm and 122 ppm respectively, while ortho-substituted halogen (50d) showed moderate activity with IC50 of 148 ppm in comparison to ascorbic acid as a standard (IC50 = 14.2 ppm). iv The resonance effect of the halogens substituents stabilised the radical intermediate and enhanced the antioxidant activities. The presence of two folds of N-H, C=O and C=S as well as other substituents in the molecular structure of the synthesised compounds played important roles to the enhancement of the biological properties. The ability of these groups to easily protonated under acidic condition and reacted with the carboxyl and phosphate groups of the bacterial surface further enhanced the antibacterial activities.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Ainaa Nadiah, Abd Halim
author_facet	Ainaa Nadiah, Abd Halim
author_sort	Ainaa Nadiah, Abd Halim
title	Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties
title_short	Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties
title_full	Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties
title_fullStr	Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties
title_full_unstemmed	Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties
title_sort	synthesis and characterisation of bis(thiourea) derivatives and studies of their biological properties
granting_institution	Universiti Malaysia Sarawak
granting_department	Faculty of Resource Science & Technology
publishDate	2017
url	http://ir.unimas.my/id/eprint/23866/5/Ainaa%20Nadiah.pdf
_version_	1794022997975105536

Synthesis and Characterisation of Bis(thiourea) Derivatives and Studies of their Biological Properties

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