Ng, Shean Yeaw (2017) Structural diversity chemosystematics and biological potential of Bornean liverworts (order jungermanniales). Doctoral thesis, Universiti Malaysia Sabah.
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Abstract
Natural products played a critical role in the development of modern drugs. Over the past 30 years, up to 50 percent of the approved drugs are derived from natural products and more than 75 percent of them are derived from plants. High incidence of cancer, rising rate of infection and inflammation due to antibiotic-resistant bacteria have admonished scientists to look for alternative ways to combat these major medical concerns. Marchantiophyta (liverworts), representing lower plant which are grouped under Bryophytes, has been reported to synthesize diverse array of chemical structures and show several interesting biological activities. Although there are many reports pertaining to liverworts chemistry, yet the information about Bornean liverworts is still scarce. Present study aimed i) to evaluate the structural diversity of selected Bornean liverworts ii) to investigate the chemosystematics of isolated secondary metabolites from collected populations iii) to determine the antibacterial property of pure compounds against human pathogenic bacteria and iv) to investigate the anti-proliferative effect of pure compounds on selected cancer cell lines. Secondary metabolites present in five species of liverworts (Order Jungermanniales) were isolated using chromatographic technique and their spectral data obtained via NMR, HRMS, FfIR and polarimeter. A total of 29 compounds were isolated; a total of 10 new compounds, with another 19 known metabolites. These compounds were sesquiterpenes and diterpenes with interesting chemical skeleton and functionalities. Some of these compounds showed excellent profiles as chemotaxonomical markers, particularly for Mastigophora diclados. Isolated compounds were also subjected to bioassay against antibiotic resistant clinical bacteria and cancer cell lines (HL-60, B16-Fl0, A549, and HT-29). Chandonanol (CH-1) isolated from Chandonanthus hirtel/us exhibited bactericidal activity against Staphylococcus aureus and Escherichia coli where the MIC/MBC ratio was less than four. In addition, herbertene-1,2-diol (MD- 5) isolated from Mastigophora diclados showed inhibition against HL-60 cells in a dose-dependent manner through induction of apoptosis. The underlying mechanism of action was via intrinsic mitochondrial pathway by up-regulation of p53 and regulated the ratio of Bax/Bcl-xl in the cells. The compound cis-3,14-clerodadien- 13-ol (SA-2) isolated from Schistochila acuminata displayed weak cytotoxic inhibition against 816-FlO cells and was not taken forward for other in-depth analysis. In conclusion, this study has provided valuable information pertaining to the diversity of secondary metabolites in the species studied. It is apparent that information obtained could be used for taxonomical interpretation and as reference in the formulation of lead pharmaceutical candidates.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Keyword: | Natural products, Drugs, Marchantiophyta, Liverworts |
| Subjects: | R Medicine > RS Pharmacy and materia medica > RS153-441 Materia medica > RS160-167 Pharmacognosy. Pharmaceutical substances (Plant, animal, and inorganic) |
| Department: | INSTITUTE > Institute for Tropical Biology and Conservation |
| Depositing User: | DG MASNIAH AHMAD - |
| Date Deposited: | 15 Dec 2023 16:08 |
| Last Modified: | 15 Dec 2023 16:08 |
| URI: | https://eprints.ums.edu.my/id/eprint/37861 |
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