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Two species of bryozoa, Pterocella vesiculosa and Plumatella repens, were investigated in an endeavour to isolate and characterise novel secondary metabolites. Analysis of fractions derived from chromatography of a dichloromethane extract of Pterocella vesiculosa, indicated the probable presence of β-carboline and pterocellin alkaloids. Continued separation led to further purification of some pterocellin alkaloids, however the characteristic ultraviolet chromatogram that is produced by pterocellins could not be found in any of the fractions analysed. Despite this, further investigations by thin layer chromatography, tandem mass spectrometry and high resolution mass spectrometry suggested structural similarities between metabolites from polar fractions and known pterocellin alkaloids. In the process of isolating these polar, pterocelli...
A chemical survey of 58 marine samples obtained from three sites around Tauranga New Zealand was undertaken in an effort to identify new metabolites. MTT assays using HeLa and P388 cell lines were carried out to determine if any of the samples contained bioactive compounds. For each sample, a crude extract was obtained and analysed by Liquid Chromatography Mass Spectrometry (LCMS). The chromatogram traces were examined and fives samples containing potential metabolites of interest were chosen for further investigation. Of the five samples two were identified from preliminary taxonomic analysis as Lyngbya sp. (cyanobacterium) and Cliona celata (a sponge). The compound targeted in Lyngbya sp. was thought to potentially be a new peptide and the Cliona celata compounds contained bromine atoms. These two samples were extracted in bulk and ...
Iron is an essential element for human physiological function. However, excess free iron could participate in the formation of reactive oxygen species via the Fenton reaction and is thought to be the primary mechanism for the pathogenesis of diseases related to iron excess. Prevention of the oxidative damage caused by reactive oxygen species can be accomplished by using selective iron-binding compounds. Beech honeydew honey has been found to have an exceptionally high level of iron-binding antioxidant activity. Due to that, the focus of the research in this thesis has been to isolate the compound(s) responsible for the activity and identify their molecular structure. The stability of the antioxidants on exposure to heat and high and low pH was investigated to get a better understanding of the conditions which could be used when develop...
Cyanobacteria (blue-green algae) are a group of ancient prokaryotic organisms which have become synonymous with water quality deterioration. An array of compounds is produced by aquatic cyanobacteria, the largest group being the oligopeptides. A major class of cyanobacterial oligopeptides are the microcystins; cyclic heptapeptides which contain the unique amino acid Adda (3 amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid). Due to their ability to inhibit protein phosphatases 1 and 2A and as they are concentrated in the liver, microcystins can be highly toxic to animals. Anabaenopeptins are cyclic hexapeptides which contain a carbonyl-linked sidechain amino acid and a ring which is cyclised through the sidechain amine of the position two D-lysine. Matrix-assisted laser desorption/ionisation-time of flight mass spectromet...
To a natural-products chemist, the term "natural products" does not refer to all compounds from natural sources, as the name might imply. It is specifically used to refer to compounds known as secondary metabolites, structurally complex molecules, often of unknown function, with very limited biological distribution.
Four new alkaloids, pterocellins C−F (1–4), have been isolated from the New Zealand marine bryozoan Pterocella vesiculosa. Structural elucidation was achieved through NMR spectroscopic and mass spectrometric analysis and comparison of spectroscopic data with that of the known compounds pterocellins A and B. The biological activities of 1–4 were assessed in a number of different assay systems and compared with those of pterocellins A and B.
A new alkaloid, 5-bromo-8-methoxy-1-methyl-β-carboline (1), has been isolated from the New Zealand marine bryozoan Pterocella vesiculosa. Structural elucidation was achieved through NMR spectroscopic and mass spectrometric analysis, and a single-crystal X-ray diffraction analysis of 1 was performed. The biological activity of 1 was assessed against P388 murine leukemia cells and three microorganisms and compared with that of a number of related β-carboline alkaloids.
Introduction – The tolyporphins are metabolites isolated from the cyanobacterium Tolypothrix nodosa, comprising a porphyrin-like macrocycle with C-glycoside, hydroxide or acetate substituents. Previous studies of porphyrins by MALDI/LDI-TOF MS indicate that strong radical cations and anions are usually observed in the parent spectra with little fragmentation of the macrocycle. The spectra of the tolyporphins were obtained and trends in the series utilised to partially characterise two new analogues. Objective – To examine tolyporphins by LDI-TOF MS and utilise trends observed to partially characterise two new analogues. Methodology – The tolyporphins were analysed by LDI-TOF MS in positive and negative ion mode and by a post source decay method (LIFT) in positive ion mode. Tolyporphin A was also analysed by MALDI-TOF MS for comparison....
Cyanobacteria (blue-green algae) are a group of ancient prokaryotic organisms dating back between three and four billion years.¹ They have been attributed with oxygenating the earth’s atmosphere² but, since the anthropogenic euthrophication of lakes, ponds and oceans, they have become synonymous with water hygiene issues.³ This is due to the alteration of the nutrient composition of their habitat to one which is optimal for growth (or blooms). Cyanobacterial blooms may simply cause foul tastes and odours,⁴ but they can also lead to the production of toxic secondary metabolites poisonous to humans and animals upon ingestion.⁵ NZ has yet to suffer a human fatality, but the deaths of several dogs in Wellington was attributed to homoanatoxin-a 1 (Chart 1) from a Phormidium species.⁶
This paper presents staff perceptions of higher education science and engineering learning communities derived from a cross-case analysis of four case studies across the New Zealand university and polytechnic sectors. First we report staff expectations and experiences in terms of infrastructure and resources, and their own careers. Staff perceptions of the diversity and differences in learning styles of their students are next, followed by the importance of practical skill development, pedagogies employed and their rationale, along with scaffolding and supporting of learning. The paper concludes by considering the nature of science (NoS) and engineering, and what messages about the NoS are presented by higher education staff. The research findings suggest that staff face conflicting demands on their time, with requirements for research...
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