Photodynamic chlorophyll a metabolites, including phytoporphyrin (phylloerythrin), in the blood of photosensitive livestock: Overview and measurement

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Show simple item record Campbell, WM en Dombroski, GS en Sharma, I en Partridge, AC en Collett, MG en 2011-11-29T19:55:55Z en 2010 en
dc.identifier.citation New Zealand Veterinary Journal 58(3):146-154 2010 en
dc.identifier.issn 0048-0169 en
dc.identifier.uri en
dc.description.abstract AIM: To validate a spectrofluorometric method for measuring chlorophyll a metabolites, specifically phytoporphyrin (= phylloerythrin), as well as the chlorins, pheophorbide a and pyropheophorbide a, in the blood of photosensitive cattle and sheep. METHODS: Standard methanolic solutions of pheophorbide a (25 µM), pyropheophorbide a (25 µM), and phytoporphyrin (<3.7 µM) were prepared. Serum and plasma samples were obtained from cattle (n=5), sheep (n=3), and one alpaca, with clinical facial eczema (i.e. photosensitive), as well as from clinically normal (n=2 of each) adult cows, recently weaned calves, and sheep (controls). Standard solutions of the three metabolites were characterised using high-performance liquid chromatography (HPLC), with mass spectrometry, in conjunction with absorption and emission spectral data, and were compared with sera from photosensitive animals. In the latter, phytoporphyrin was the only metabolite detected. Calibration curves were prepared by adding different ratios of methanol and standard solutions of phytoporphyrin in methanol to diluted serum from control animals. Peak areas of fluorescence spectra were determined in samples from photosensitive animals. RESULTS: Pheophorbide a and pyropheophorbide a produced typical chlorin spectra, and had excitation/emission maxima of 408/669 nm and 409/669 nm, respectively. Phytoporphyrin showed a typical porphyrin fluorescence spectrum, with excitation/emission maxima of 425/644 nm. Pyropheophorbide a and phytoporphyrin had very similar chromatographic retention times, the same chemical formula and same mass, but were distinguishable by differences in their absorption spectra. In sera from photosensitive animals, the fluorescence emission at 644 nm was shown to arise solely from phytoporphyrin and not from any other chlorophyll a metabolites. Calibration curves using sera and plasma from control animals gave reliable measurements of phytoporphyrin in the range 0.4–6 µM. The sera of facial eczema-affected cattle and sheep had concentrations of phytoporphyrin ranging from 0.4 to 1.8 and 0.9 to 2.8 µM, respectively. Haemolysed serum samples were not suitable for determination of phytoporphyrin with this method. CONCLUSIONS AND CLINICAL RELEVANCE: A spectrofluorometric method for the quantification of phytoporphyrin in the blood of photosensitive animals has been validated, and can be applied to the measurement of other chlorophyll a metabolites in blood. This will be a useful tool in the further investigation of the cause and pathogenesis of idiopathic photosensitivities of farm animals. en
dc.publisher Taylor & Francis en
dc.relation.ispartofseries New Zealand Veterinary Journal en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from en
dc.rights.uri en
dc.title Photodynamic chlorophyll a metabolites, including phytoporphyrin (phylloerythrin), in the blood of photosensitive livestock: Overview and measurement en
dc.type Journal Article en
dc.identifier.doi 10.1080/00480169.2010.67517 en
pubs.issue 3 en
pubs.begin-page 146 en
pubs.volume 58 en
dc.rights.holder Copyright: Taylor & Francis en
dc.identifier.pmid 20514089 en
pubs.end-page 154 en
dc.rights.accessrights en
pubs.subtype Article en
pubs.elements-id 174546 en Engineering en Chemical and Materials Eng en
pubs.record-created-at-source-date 2011-11-30 en
pubs.dimensions-id 20514089 en

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