John L. Laseter

Singlet oxygen and biological systems

Abstract Singlet oxygen is receiving increasing attention as a reactive species in many chemical and biological systems. It can be generated easily by microwave discharge, chemically or by photosensitized irradiation and also is found to be a common reactive atmospheric pollutant generated by solar radiation. Singlet oxygen reacts with a host of materials which are unaffected by “normal” oxygen. From a biological standpoint, there is strong evidence that living systems have mechanisms for the protection of molecules such as lipids and nucleic acids which would otherwise be damaged by exogenous singlet oxygen. Interestingly, other constituents such as chlorophyll and riboflavin found in living systems, are in turn excellent singlet oxygen sensitizers. Furthermore, there are indications that living systems may produce singlet oxygen internally, for example in the enzyme peroxidase-catalase system. The presence of singlet oxygen in biological systems has led to new theories on carcinogenesis. In view of these biological implications, a selective survey has been made of the current literature on singlet oxygen concentrating on the involvement of this species in the aforementioned processes. Examples from the chemical literature are presented which illustrate the scope of singlet oxygen reactions and/or serve as models for biochemical processes.

Enhancement of Ultraviolet Detectability of Fatty Acids for Purposes of Liquid Chromatographic-Mass Spectrometric Analyses

Abstract A technique for benzyl derivatization of fatty acids which results in enhanced ultraviolet absorption with a concomittant increase in sensitivity in liquid chromatographic (LC) separations has been developed. Benzylation prior to liquid chromatographic separation also provides a uniform enhancement of response for fatty acids which permits direct relative quantization without acquisition of additional calibration data. After removal of excess solvent from eluted compounds mass spectra were determined using a direct probe which confirmed the benzyl ester structures. A discussion of spectral data and the advantages of using mass spectrometry as an ancillary tool to liquid chromatography is also discussed.

Dye-sensitized photooxidation of phenanthrene☆

Abstract The dye-sensitized photooxidation of phenanthrene has been studied in a two-phase system employing n -hexane and water. Rose bengal was used as a sensitizer. A number of volatile oxidation products are observed and characterized by GC-MS-COM methods. The data suggest that one oxidation route involves the conversion of phenanthrene to 9,10-epoxy-9,10-dihydrophenanthrene which is related to the potentially carcinogenic arene oxides of more highly condensed polynuclear hydrocarbons. These results may have significance in connection with the enhancement of aberrant effects on biological systems produced by polynuclear hydrocarbons upon exposure to light.

Total lipid and sterol components of Rhizopus arrhizus - Identification and metabolism.

Abstract The total lipid levels and the incorporation of [14C]acetate during the life cycle of the fungus Rhizopus arrhizus were investigated. The total lipid abundances ranged between 2.2 and 15.3% of the tissue, reaching the maximum midway through the 6-day growth period. The sporangiospores contained 2.65% total lipids. The sterols were also investigated and ranged in concentration from 1.88 to 9.1% of the total lipids during the growth period. 4,4-Dimethyl, 4α-methyl, and 4-des-methyl sterols were tentatively identified by tlc and the latter group separated and identified by combined glc-ms. The predominant 4-desmethyl sterols were ergosta-Δ5,7,22-trienol (ergosterol), ergosta-Δ7,22-dienol (5-dihydroergosterol), ergost-Δ7-enol (fungisterol), and the tentatively identified ergosta-Δ5,7,14-trienol in relative concentrations of 24.6, 58.8, 9.9, and 6.7%, respectively. The sterol components of the spores were qualitatively identical to those of the mycelial tissues, but several minor components remain to be identified.

Fatty Acid Ethyl Esters of Rhizopus arrhizus

Gas chromatographic and mass spectrometric analyses on selected lipid fractions revealed for the first time the presence of ethyl esters of long-chain fatty acids as biological products. Ethyl esters of oleic, palmitic, and stearic acids were detected in relative concentrations of 21.2, 2.4, and 1.5 percent, respectively, of the total methyl and ethyl ester fraction. Both saturated and unsaturated ethyl esters contain pronounced mass spectral fragments at a mass-to-charge ratio of 88.

Two populations of aliphatic hydrocarbons of teratoma and habituated tissue cultures of tobacco

Abstract Teratoma and habituated tissue cultures of tobacco grown under identical conditions were examined for the presence of paraffinic hydrocarbons. The teratoma tissues contained n -C 29 , 2-methyl C 30 ( iso C 31 ) and n -C 31 as the major alkane components and their distribution pattern was qualitatively identical to the seedling tissue alkanes (C 22 –C 34 ). Habituated tissues contained a different population of alkanes ranging in carbon chain length from C 17 to C 28 . The predominant alkane components were n -C 23 , n -C 22 , and n -C 24 in decreasing concentrations respectively. A tissue culture system is presented where the Population I hydrocarbons (C 16 –C 28 ) are synthesized separately and independently of Population II hydrocarbons (C 27 –C 34 ).

Fatty acids of Pinus elliottii tissues.

Abstract The total fatty constituents of slash pine ( Pinus elliottii ) tissue cultures, seeds and seedlings were examined by GLC and MS. Qualitatively, the fatty acid composition of these tissues was very similar to that reported for other pine species. The fatty acid contents of the tissue cultures resembled that of the seedling tissues. In addition to the fatty acids common to botanical materials, Δ 5 -C 18 and -C 20 nonmethy lene-interrupted polyunsaturated acids were present in low relative abundances. The branched-chain C 17 acid reported for several other Pinus species was confirmed as the anteiso isomer.

Reactions of Singlet Oxygen with Pine Pollen

Exposure of pine pollen to single oxygen, generated in an aqueous environment, resulted in a decrease in the relative quantities of unsaturated fatty acids that could be recovered by solvent extraction of surface and near surface pollen lipids. The involvement of excited oxygen was confirmed by substitution of deuterium oxide for water, which led to a twofold greater decrease in the unsaturated acids. The potential environmental and biomedical implications of these observations are discussed in terms of this model system.

Volatile terpenoids from aeciospores of Cronartium fusiforme

Abstract Aeciospores of Cronartium fusiforme isolated from slash pine ( Pinus elliottii ) trees were analyzed for volatile terpenoids by GLC and GLC-MS. α-Pinene, β-pinene, Δ 3 -carene, myrcene, linonene, β-phellandrene, and δ-terpinene were the major monoterpenoid hydrocarbons present with only traces of camphene. A number of monoterpenoid alcohols were also present of which terpinen- 4-ol predominated. Among the various acyclic sesquiterpenes present, β-farnesene and β-citronellol were identified. Several aromatic compounds were also observed, including o -cresol.

Gas chromatography-mass spectrometry study of sterols from Pinus elliotti tissues☆

Abstract A comparative study of the sterol components of slash pine ( Pinus elliottii ) callus tissue cultures, seeds, and seedlings was carried out using GC-MS techniques. Cholesterol, desmosterol, campesterol, stigmasterol, sitosterol and cycloeucalenol were identified in all tissues while lophenol and 24-methylenelophenol were identified in only the seed and seedlings. 24-Ethylidenelophenol was detected in trace concentrations in only the seedlings. Sitosterol was the predominant sterol component, i.e. 80·8, 38·1 and 47·8% of the tissue culture, seed and seedling sterols, respectively.