No abstract

Extensive regional droughts are already a major problem on all inhabited continents and severe regional droughts are expected to become an increasing and extended problem in the future. Consequently, extended use of available drought resistant food plants should be encouraged. Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile are excellent candidates in that respect because they are established drought resistant edible plants from the semi-arid Caatinga region. From a food safety perspective, increased utilization of these plants would necessitate detailed knowledge about their chemical constituents. However, their chemical compositions have previously not been determined. For the first time, the non-polar constituents of B. laciniosa, N. variegata and E. spectabile have been identified. This is the first thorough report on natural products from N. variegata, E. spectabile, and B. laciniosa. Altogether, 20 non-polar natural products were characterized. The identifications were based on hyphenated gas chromatography-high resolution mass spectrometry (GC-HRMS) and supported by 1D and 2D Nuclear Magnetic Resonance (NMR) plant metabolomics.

Mass spectrometry (MS) 3.5 Biological activity 3.5.1 15-Lipoxygenase inhibition 3.5.2 DPPH scavenging activity 3.5.3 Artemia toxicity test 4. Results and discussion 4.1. Novel aminoalkaloids and GHB-derived natural products from European white-berry mistletoe (Viscum album L.) 4.2. A novel dihydrostilebenoid glucoside and seven other natural products isolated from dawn redwood (Metasequoia glyptostroboides Hu & Cheng) 4.3. A novel acylated C-glycosylflavone and six other natural products from Zamioculcas zamiifolia 4.4. Twenty non-polar natural products from three Bromeliaceae spp. 4.5. Novel aromatic compounds from Narthecium ossifragum L. References I wish to thank my main supervisor Professor Torgils Fossen for excellent supervision. Fossen has willingly shared of his knowledge and encouraged me in the daily struggle of making procedures work and figuring out the meaning of the results. Assistant supervisor Professor Svein Haavik has provided valuable discussions and input at critical stages during the development of the thesis. Professor Emeritus George W. Francis has most kindly used some of his time to discuss with me and share of his knowledge accumulated through more than four decades of natural products research. Francis has also contributed to improvement of language of both papers and thesis. Special word of thanks to Professor Jackson Roberto Guedes da Silva Almeida (UNIVASF, Brazil), Professor Frederic Dupont (Universite Lille 2) and Professor Dag Olav Øvstedal (University of Bergen) for providing significant quantities of the plant material used in this thesis. All co-authors on papers included in the thesis are appreciated for their collaboration and valuable contributions. Dr. Bjarte Holmelid and Mr. Terje Lygre have my gratitude for the recording of high-resolution mass spectra. Now retired principal engineer Atle Aaberg have my gratitude for his technical assistance. I wish to thank all the people at the Department of Chemistry including past and current members of the research group in Pharmacognosy. You have all contributed to a friendly, inspiring and good working environment. Colleagues and my two closest superiors, apothecary Kine Risberg and manager Rikke Landsvik Berge at Apotek1 Oasen have my deepest gratitude. Their friendly attitude and flexibility has made it possible to continue writing papers and completing the thesis during the two years from August 2015 to September 2017 next to a full time job as pharmacist. Open Access publication of paper VI "Non-polar natural products from Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile (Bromeliaceae)" were kindly funded by Centre for Pharmacy, University of Bergen.

Context: The European white-berry mistletoe [Viscum album L. (Loranthaceae)] is among the oldest known medicinal plants. At present the most important application of mistletoe extracts is in the treatment of cancer. However, natural products specific to mistletoe have rarely been encountered in the current literature. Objective: To discover novel natural products specific to European mistletoe. Materials and methods: European mistletoe was extracted with methanol, purified to partition against diethyl ether and further purified with XAD-7 column chromatography. Pure compounds were separated by Sephadex column chromatography and preparative HPLC. The structures of the novel compounds were established using a combination of several 2D NMR spectroscopic techniques and mass spectrometry. Results: A new type of natural product derived from the methyl ester of g-hydroxybutyric acid (GHB) coupled to hydroxybenzoic acids, namely 3-(3 0 -carbomethoxypropyl) gallic acid and 3-(3 0 -carbomethoxypropyl)-7!3 00 -protocatechoyl galloate were characterized from European white-berry mistletoe. Condensation of the 3-hydroxyl of gallic acid with the 4-hydroxyl of GHB significantly reduced the radical scavenging properties of the former compound. Discussion and conclusion: The characterized compounds define a novel group of natural products that may be of particular interest because it appears that the two new compounds are not closely related to any known natural product. Keywords2D NMR, 3-(3 0 -carbomethoxypropyl)gallic acid, 3-(3 0 -carbomethoxypropyl)-7!3 00 -protocatechoyl galloate, g -hydroxybutyric acidHistory

After the sensational rediscovery of living exemplars of the Cretaceous relict Metasequoia glyptostroboides—a tree previously known exclusively from fossils from various locations in the northern hemisphere, there has been an increasing interest in discovery of novel natural products from this unique plant source. This article includes the first complete compilation of natural products reported from M. glyptostroboides during the entire period in which the tree has been investigated (1954–2014) with main focus on the compounds specific to this plant source. Studies on the biological activity of pure compounds and extracts derived from M. glyptostroboides are reviewed for the first time. The unique potential of M. glyptostroboides as a source of bioactive constituents is founded on the fact that the tree seems to have survived unchanged since the Cretaceous era. Since then, its molecular defense system has resisted the attacks of millions of generations of pathogens. In line with this, some recent landmarks in Metasequoia paleobotany are covered. Initial spectral analysis of recently discovered intact 53 million year old wood and amber of Metasequoia strongly indicate that the tree has remained unchanged for millions of years at the molecular level.