PubMed · 7059975
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T J Dougherty. 1982. Variability in hematoporphyrin derivative preparations.. https://pubmed.ncbi.nlm.nih.gov/7059975/
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To lower cholesterol, phytosterols are currently introduced as food additives, where they may become oxidized. In addition, specific biological effects of oxyphytosterols are suggested by the recent molecular clarification of the phytosterol storage disease as a dysfunctional mutation of an active sterol reexporter potentially regulated by oxidized phytosterols. We therefore studied the hydroxybenzotriazole-mediated PbO(2)-driven oxidation of phytosterols and compared it to the oxidation of cholesterol. We prepared, identified, and purified standards of 14 oxidation products of two major phytosterols. The gas chromatographic mass spectrometric characteristics of the 7alpha- and 7beta-hydroxy-, 5alpha,6alpha-epoxy, 5beta,6beta-epoxy, 7keto-, 3beta,5alpha,6beta-trihydroxy-, 3keto-, and 7-dehydro-derivatives of beta-sitosterol and stigmasterol are presented. The method also provided a convenient access to prepare 18O-labeled oxyphytosterols of high chemical and isotopic purity and can easily be extended to further phytosterols and -stanols. This enables the gas chromatography-mass spectrometry analysis of oxyphytosterols and the study of their biological effects.
Time-resolved fluorescence spectroscopic measurements of second-generation new photosensitizer of hematoporphyrin monomethyl ether (HMME) were carried out in the physiological saline and different human serums by picosecond fluorescence lifetime spectrometer, respectively. The objective was to assess the fluorescence lifetime of HMME as a new enhanced contrast parameter between normal and malignant tissues for the photodynamic diagnosis of various cancers. The influence of emission wavelength and photosensitizer concentration, on the lifetime of HMME was also presented. No significant change in fluorescence decay was found between emission wavelength 625 and 690 nm. The lifetimes of HMME diluted in the physiological saline and human serum were about 14.6 and 16.6 ns, respectively. Experimental results also indicate a quite stable behavior with a decay time of 16.6 ns when HMME was diluted with different concentration. Time-resolved fluorescence spectrum of HMME can serve as a characteristic marker for optical biopsy of the malignant tissue because of the useful property of selective retention in malignant tumors after intravenous injection. Furthermore, the results in this study will contribute to the improvement of nanosecond fluorescence lifetime imaging method.
A photoacoustic (PA) study of the relaxation processes of the excited states of photosensitizers in the presence of oxygen and chemical acceptors is described. It has been predicted theoretically that the ratio of PA amplitudes with and without acceptor depends on two parameters alpha and beta, related to the sensitizer and to the acceptor properties, respectively. Experimental studies were carried out on solutions of hematoporphyrin IX and methylene blue. The addition of an acceptor, specific to the singlet oxygen, like tetramethyl ethylene or furfuryl alcohol, appears to decrease significantly the photoacoustic signal amplitude within the band of absorption.