Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain

Endophytes are microorganisms that inhabit host plants a symptomatically and have a fascinating potential as a source of new drug leads in many sectors. Studying microorganisms from a variety of biotopes increases the chances to isolate structurally diverse metabolites. In this respect, psychrophile...

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Main Author:	Mohamed Hussain, Fatimah Bebe
Format:	Thesis
Language:	English
Published:	2021
Subjects:	Nutrition Pharmaceutical chemistry
Online Access:	https://ir.uitm.edu.my/id/eprint/46790/1/46790.pdf
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spelling	my-uitm-ir.467902022-03-07T06:32:18Z Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain 2021-02 Mohamed Hussain, Fatimah Bebe Nutrition Pharmacognosy. Pharmaceutical substances (Plant, animal, and inorganic) Pharmaceutical chemistry Endophytes are microorganisms that inhabit host plants a symptomatically and have a fascinating potential as a source of new drug leads in many sectors. Studying microorganisms from a variety of biotopes increases the chances to isolate structurally diverse metabolites. In this respect, psychrophiles from the Arctic fulfil the criteria of an interesting source of potential new drugs. However, endophytes from tropical regions should be able to resist stronger competition through the production of various antimicrobial agents. This study included 31 endophytic fungi that were isolated from ten plants from Longyearbyen, Svalbard Island, Norway, and 54 endophytic fungi obtained from three plants belonging to the Uncaria family growing in UiTM Puncak Alam’s biological reserve, Malaysia. The objective of this study was to isolate secondary metabolites from endophytic fungi whose extracts demonstrated antimicrobial properties. Ethyl acetate extracts of all the isolates were analysed by HPLC and evaluated for preliminary screening of antimicrobial activity against S. aureus, E. faecium, P. aeruginosa, E. coli, and C. albicans, using the MTT assay. From the analysis of the above data, 4 out of 85 (3 Malaysian and 1 Arctic) endophytic fungal isolates were selected for further investigation. These include Nigrospora oryzae, Diaporthe phaseolorum, Trichoderma virens, and Poaceicola sp., which were identified by morphological and genetic techniques. The crude extracts were fractionated, and their components purified by semi-preparative HPLC. Chemical structures were determined based on spectroscopic methods including MS, NMR, UV/Vis, ECD and X-ray diffraction techniques. The Nigrospora oryzae extract included two major and three minor compounds. They were subsequently identified as pestalopyrone, hydroxypestalopyrone, 4-dehydroxyaltersolanol A, macrosporin, and altersolanol B, respectively, via comparison of their spectral data. The absolute configuration of 4-dehydroxyaltersolanol A was unambiguously confirmed by X-ray crystallography, ECD spectral analysis in combination with quantum chemistry simulations. An extract derived from Diaporthe phaseolorum was found to contain cytochalasins H and J. From the Trichoderma virens culture, two compounds were identified, namely gliocladic and heptelidic acids. Finally, from the culture of Poaceicola sp. one known compound was identified, annularin D. Five new polyketides, including (-)-cleanarol C (C13H14O4), (-)-3,8-dihydroxy-3-hydroxymethyl-6-methoxy-4,5-dimethyl-isochroman-1-one (C13H16O6) and svalbardines A (C16H14O6), B (C32H28O12) and C (C10H14O4) had their structures established. Svalbardine A was determined as a new pyranochromene, while svalbardine B was assigned a new carbon skeleton based on a spiro chromone-oxanaphthalene frame. Svalbardine C was determined as a hydroxylated derivative of annularin D, while the remaining two compounds were new enantiomers of known structures. Most of the known compounds mentioned above were previously recognised for their antimicrobial properties and can be regarded as responsible for the overall activity of the crude extracts during the MTT screening, thus vindicating the initial hypothesis. It is therefore believed that this work could be the basis for a more targeted search of novel antimicrobials. 2021-02 Thesis https://ir.uitm.edu.my/id/eprint/46790/ https://ir.uitm.edu.my/id/eprint/46790/1/46790.pdf text en public phd doctoral Universiti Teknologi MARA Faculty of Pharmacy Sultan, Sadia (Assoc. Prof. Dr.)
institution	Universiti Teknologi MARA
collection	UiTM Institutional Repository
language	English
advisor	Sultan, Sadia (Assoc. Prof. Dr.)
topic	Nutrition Nutrition Pharmaceutical chemistry
spellingShingle	Nutrition Nutrition Pharmaceutical chemistry Mohamed Hussain, Fatimah Bebe Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain
description	Endophytes are microorganisms that inhabit host plants a symptomatically and have a fascinating potential as a source of new drug leads in many sectors. Studying microorganisms from a variety of biotopes increases the chances to isolate structurally diverse metabolites. In this respect, psychrophiles from the Arctic fulfil the criteria of an interesting source of potential new drugs. However, endophytes from tropical regions should be able to resist stronger competition through the production of various antimicrobial agents. This study included 31 endophytic fungi that were isolated from ten plants from Longyearbyen, Svalbard Island, Norway, and 54 endophytic fungi obtained from three plants belonging to the Uncaria family growing in UiTM Puncak Alam’s biological reserve, Malaysia. The objective of this study was to isolate secondary metabolites from endophytic fungi whose extracts demonstrated antimicrobial properties. Ethyl acetate extracts of all the isolates were analysed by HPLC and evaluated for preliminary screening of antimicrobial activity against S. aureus, E. faecium, P. aeruginosa, E. coli, and C. albicans, using the MTT assay. From the analysis of the above data, 4 out of 85 (3 Malaysian and 1 Arctic) endophytic fungal isolates were selected for further investigation. These include Nigrospora oryzae, Diaporthe phaseolorum, Trichoderma virens, and Poaceicola sp., which were identified by morphological and genetic techniques. The crude extracts were fractionated, and their components purified by semi-preparative HPLC. Chemical structures were determined based on spectroscopic methods including MS, NMR, UV/Vis, ECD and X-ray diffraction techniques. The Nigrospora oryzae extract included two major and three minor compounds. They were subsequently identified as pestalopyrone, hydroxypestalopyrone, 4-dehydroxyaltersolanol A, macrosporin, and altersolanol B, respectively, via comparison of their spectral data. The absolute configuration of 4-dehydroxyaltersolanol A was unambiguously confirmed by X-ray crystallography, ECD spectral analysis in combination with quantum chemistry simulations. An extract derived from Diaporthe phaseolorum was found to contain cytochalasins H and J. From the Trichoderma virens culture, two compounds were identified, namely gliocladic and heptelidic acids. Finally, from the culture of Poaceicola sp. one known compound was identified, annularin D. Five new polyketides, including (-)-cleanarol C (C13H14O4), (-)-3,8-dihydroxy-3-hydroxymethyl-6-methoxy-4,5-dimethyl-isochroman-1-one (C13H16O6) and svalbardines A (C16H14O6), B (C32H28O12) and C (C10H14O4) had their structures established. Svalbardine A was determined as a new pyranochromene, while svalbardine B was assigned a new carbon skeleton based on a spiro chromone-oxanaphthalene frame. Svalbardine C was determined as a hydroxylated derivative of annularin D, while the remaining two compounds were new enantiomers of known structures. Most of the known compounds mentioned above were previously recognised for their antimicrobial properties and can be regarded as responsible for the overall activity of the crude extracts during the MTT screening, thus vindicating the initial hypothesis. It is therefore believed that this work could be the basis for a more targeted search of novel antimicrobials.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Mohamed Hussain, Fatimah Bebe
author_facet	Mohamed Hussain, Fatimah Bebe
author_sort	Mohamed Hussain, Fatimah Bebe
title	Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain
title_short	Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain
title_full	Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain
title_fullStr	Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain
title_full_unstemmed	Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain
title_sort	secondary metabolites from selected fungal endophytes from uncaria sp. and svalbard plants / fatimah bebe mohamed hussain
granting_institution	Universiti Teknologi MARA
granting_department	Faculty of Pharmacy
publishDate	2021
url	https://ir.uitm.edu.my/id/eprint/46790/1/46790.pdf
_version_	1783734768825794560

Secondary metabolites from selected fungal endophytes from uncaria SP. and svalbard plants / Fatimah Bebe Mohamed Hussain

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