Allan L Mackenzie

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Gymnodimine C (1), an oxidized analogue of the spiro-imine algal toxin gymnodimine (3), was isolated from extracts of the cells of Karenia selliformis. The structure of gymnodimine C, determined by one- and two-dimensional 1H NMR spectroscopy and mass spectrometry, was found to be isomeric with gymnodimine B (2) at C-18.
We have developed a simple and effective method for isolating pectenotoxin-2 (PTX-2) from Dinophysis cells collected from a natural bloom. A two-step extraction procedure followed by two column chromatography steps produced PTX-2 in high purity suitable for use as an analytical standard and for toxicological studies. Incubation of purified PTX-2 with the(More)
A spiroimine, gymnodimine B (1), was isolated from cells recovered by filtration from cultures of a marine dinoflagellate, Gymnodinium sp. Its structure was identified by one- and two-dimensional NMR spectroscopy and mass spectrometry. Gymnodimine B is similar in structure to gymnodimine (2) but contains an exocyclic methylene at C-17 and an allylic(More)
Preparative HPLC purification of a side-fraction obtained during purification of 44,55-dihydroxyyessotoxin (6) afforded fractions containing previously unidentified yessotoxin analogues. Careful analysis of these fractions by HPLC-UV, LC-MS3, and NMR spectroscopy, revealed the identities of some of these analogues as 45-hydroxy-46,47-dinoryessotoxin (1),(More)
The 1,3-enone isomer (1) of heptanor-41-oxoyessotoxin (2) was isolated from extracts of Protoceratium reticulatum during large-scale production of yessotoxin (4). We found that 2 readily isomerizes to 1 in the presence of dilute ammonia and present evidence for the existence of 40-epi-2 (3) that also isomerizes to 1. 1-3 were detected by LC-MS methods both(More)
OBJECTIVE To determine the effects of medetomidine, administered i.v., on serum insulin and plasma glucose concentrations in clinically normal dogs. ANIMALS 6 healthy adult Beagles. PROCEDURE Dogs were randomly assigned to each of 3 treatments in a prospective cross-over study design. Serum insulin and plasma glucose concentrations were determined(More)
Two novel pectenotoxins (PTXs), PTX-13 and -14, were isolated from extracts of Dinophysis acuta collected from the west coast of South Island, New Zealand. The compounds were identified as oxidized analogues of PTX-2 by NMR spectroscopic and LC-MS studies. PTX-13 (32R-hydroxyPTX-2) corresponds to the unidentified analogue PTX-11x reported by [Suzuki et al.,(More)
Yessotoxin 32-O-[beta-L-arabinofuranosyl-(5'-->1'')-beta-L-arabinofuranoside] (3) was isolated from extracts of Protoceratium reticulatum during a large scale isolation of yessotoxin (1). The structure was characterized by mass spectrometry and NMR spectroscopy. Di-glycoside-3, along with the corresponding mono-glycoside (2) were detected in cultures of P.(More)
44,55-Dihydroxyyessotoxin (1) was isolated from extracts of Protoceratium reticulatum and identified by analysis of its one- and two-dimensional NMR and mass spectra. In addition, LC-MS methods revealed the presence of compounds tentatively identified as (44-R,S)-44,55-dihydroxy-41a-homoyessotoxin (2) and (44-R,S)-44,55-dihydroxy-9-methyl-41a-homoyessotoxin(More)
Potassium chloride (KCl: 330 mg/ml) was assessed as an euthanasia agent in American lobsters (Homarus americanus). Two groups of 10 lobsters (408.2 to 849.9 g) were maintained at 11.9 to 12.1 degrees C ('warm') and 1.5 to 2.5 degrees C ('cold') to evaluate the possible effect of ambient temperature on response to KCl. Death was defined as time of cardiac(More)