Secondary Metabolites from Mozambican Plants
Author
Summary, in English
Products derived from different natural sources have been used for thousands of years by human beings for their everyday needs. Out of these natural sources, plants were the most affordable. Plant-derived products were used for shelter, food, and as medicines. The medicinal properties of plant-derived products played an important role in ancient civilizations, and even in the present days they are useful due to their medicinal properties.
Based on the experience acquired by humans over the years by exploiting plant-derived products or secondary metabolites, this thesis was aimed to analyse the chemical components of some plants from the Mozambican flora used in the traditional medicine for the treatment of various ailments. Extracts of Cadaba natalensis (Capparaceae), Clematis viridiflora (Ranunculaceae), Brachylaena discolor (Asteraceae) and Senna spectabilis (Fabaceae) plant species were investigated for their chemical constituents.
By fractionation based on various chromatographic methods, forty metabolites were isolated and their chemical structures were determined. Out of these, three were found to be novel metabolites, All in all, 40 secondary metabolites belonging to the three main classes of secondary metabolites were isolated and their structures were determined by high resolution NMR and MS techniques. The macrocyclic dibenzo-diazocyclododecanedione (134), (S)-2-ethyl-2-methyloxazolidin-5-one (139a), and 4-methoxy-3-methyl-2-(methylthio)-1Hindole (141) were the three novel metabolites, while the (R)-5-ethyl-5-methyloxazolidin-2-one (140) was isolated as natural product for the first time. The structures on these metabolites were determined by extensive use of
the spectroscopic techniques of NMR (1D- and 2D-NMR), IR, as well as MS data. The structures of the known compounds were determined by the same techniques, and confirmed by the comparison of their spectroscopic
data with those reported in the literature.
Isolated metabolites with interesting structural features were assayed for in vitro antiprotozoal activity towards two Leishmania strain, Leishmania amazonensis clon 1 and L. braziliensis. The quinone methide triterpenoid (29a) showed a potent antileishmanial activity against both strain with the IC50 values 4.2 and 2.8 μM, respectively compared to the positive controle miltefone with the IC50 values 5.1 and 4.9 μM, respectively. Miltefone is a current used drug to treat Leishmania. 141 with the IC50 values 25.0 and 13.2 μM, respectively, and onopordopicrin (153) with the IC50 values 13.8 and 9.7 μM, respectively, also possessed interesting antileishmanial activity, although the germacranolide epoxy derivative 154, derived from 153, was inactive against both strain tested.
Based on the experience acquired by humans over the years by exploiting plant-derived products or secondary metabolites, this thesis was aimed to analyse the chemical components of some plants from the Mozambican flora used in the traditional medicine for the treatment of various ailments. Extracts of Cadaba natalensis (Capparaceae), Clematis viridiflora (Ranunculaceae), Brachylaena discolor (Asteraceae) and Senna spectabilis (Fabaceae) plant species were investigated for their chemical constituents.
By fractionation based on various chromatographic methods, forty metabolites were isolated and their chemical structures were determined. Out of these, three were found to be novel metabolites, All in all, 40 secondary metabolites belonging to the three main classes of secondary metabolites were isolated and their structures were determined by high resolution NMR and MS techniques. The macrocyclic dibenzo-diazocyclododecanedione (134), (S)-2-ethyl-2-methyloxazolidin-5-one (139a), and 4-methoxy-3-methyl-2-(methylthio)-1Hindole (141) were the three novel metabolites, while the (R)-5-ethyl-5-methyloxazolidin-2-one (140) was isolated as natural product for the first time. The structures on these metabolites were determined by extensive use of
the spectroscopic techniques of NMR (1D- and 2D-NMR), IR, as well as MS data. The structures of the known compounds were determined by the same techniques, and confirmed by the comparison of their spectroscopic
data with those reported in the literature.
Isolated metabolites with interesting structural features were assayed for in vitro antiprotozoal activity towards two Leishmania strain, Leishmania amazonensis clon 1 and L. braziliensis. The quinone methide triterpenoid (29a) showed a potent antileishmanial activity against both strain with the IC50 values 4.2 and 2.8 μM, respectively compared to the positive controle miltefone with the IC50 values 5.1 and 4.9 μM, respectively. Miltefone is a current used drug to treat Leishmania. 141 with the IC50 values 25.0 and 13.2 μM, respectively, and onopordopicrin (153) with the IC50 values 13.8 and 9.7 μM, respectively, also possessed interesting antileishmanial activity, although the germacranolide epoxy derivative 154, derived from 153, was inactive against both strain tested.
Department/s
Publishing year
2017-11
Language
English
Full text
Document type
Dissertation
Publisher
Lund University, Faculty of Science, Department of Chemistry, Centre for Analysis and Synthesis
Topic
- Natural Sciences
Keywords
- Secondary metabolites
- Mozambique
- Medicinal plants
- Isolation
- Structural elucidation
- Antileishmanial activity
Status
Published
Supervisor
- Olov Sterner
- Amália Uamusse
ISBN/ISSN/Other
- ISBN: 978-91-7422-553-2
- ISBN: 978-91-7422-554-9
Defence date
21 December 2017
Defence time
09:30
Defence place
Lecture hall F, Center for chemistry and chemical engineering, Naturvetarvägen 14, Lund
Opponent
- Anders Vik (Associate Professor)