Identification by gas chromatography and mass spectrometry of lipids from the rat Harderian gland

Lipids from rat Harderian glands were extracted with ethyl acetate, hydrolysed with base and examined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) as trimethylsilyl (TMS), [2H9]TMS, methyl ester-TMS, picolinyl, nicotinate and nicotinylidene derivatives. The latter three derivatives were used to reveal the structures of the alkyl chains of fatty acids, alcohols and glycerol ethers, respectively. Forty-eight compounds were identified, representing about 97% of the total extracted lipids as measured by GC peak areas. The major constituents were fatty acids with chain lengths from 12 to 22 carbon atoms (mainly C18 and C20) and fatty alcohols (C16 to C26) derived from wax esters. Most of these acids and alcohols were unsaturated in the omega-7 position and were accompanied by smaller amounts of the saturated and omega-5 monounsaturated analogues. glycerol ethers were also identified for the first time in this secretion; the ether chains contained from 14 to 19 carbon atoms (mainly 16) and were straight-chain saturated, unsaturated (omega-5 and omega-7) and branched (iso). The only sterol found was cholesterol amounting to 1.24% of the total extract.     

Direct injection method for quantitation of delta-aminolevulinic acid in urine by high-performance liquid chromatography.

A highly sensitive and simple method for determining delta-aminolevulinic acid (ALA) in urine was established, using direct injection of urine into a high-performance liquid chromatographic column, with fluorometric detection after post-column derivatization with o-phthalaldehyde (OPA). The recovery of ALA was about 100% and ALA was completely separated on an ion exchange column (retention time, 38 min). The detection limit for ALA was 10 pmol (S/N = 2). The mean levels of urinary ALA of 10 healthy volunteers, 4 patients with acute intermittent porphyria, and 2 workers occupationally exposed to lead were 0.76, 5.25, and 23.54 mg/l, respectively. Because of its simplicity, the method is considered to be suitable for routine analysis of urinary ALA in the clinical laboratory.     

Characterization of porphyrins of rat Harderian gland by thin layer chromatography and mass spectrometry: no evidence for a tricarboxylic acid porphyrin

Reversed-phase TLC systems using ion-pairing reagents are described for the separation without prior derivatization of the porphyrins of rat Harderian gland. Porphyrins with R(f) values greater than protoporphyrin but smaller than coproporphyrin, representing harderoporphyrin, were labile to 1 m NaOH, which converted them to protoporphyrin, inconsistent with the established literature that harderoporphyrin is a tricarboxylic acid porphyrin. It was confirmed by HPLC/electrospray ionization MS that this 'harderoporphyrin' fraction consists of the recently characterized glycoconjugate, protoporphyrin-1-O-acyl beta-xyloside, with trace amounts of protoporphyrin-1-O-acyl beta-glucoside.     

Simultaneous determination of delta-aminolevulinic acid, porphobilinogen, levulinic acid and glycine in culture broth by capillary electrophoresis.

Capillary electrophoretic simultaneous determination of a mixture containing delta-aminolevulinic acid, porphobilinogen, levulinic acid and glycine was investigated. With increases in the sodium tetraborate buffer concentration (5-70 mM), resolution of the four components was improved, but the migration time was increased. Alternatively, with increases in the applied voltage (5-22.5 kV), a shortened migration time was seen but this adversely affected resolution. The components were separated with high resolution by using a fused-silica capillary column (75 cm x 75 microm I.D.) filled with 30 mM sodium tetraborate buffer (pH 9.3-9.4) under the applied voltage of 20 kV (constant voltage mode). When the established method was applied to the culture broth of Rhodopseudomonas sphaeroides, a photosynthetic bacterium, the four components mentioned above were separated with good resolution. Furthermore, the use of this method would provide a fast, sensitive and specific method for monitoring the administration of delta-aminolevulinic acid in photodynamic cancer therapy, for the measurement of delta-aminolevulinic acid dehydratase activity in erythrocytes, and for testing the delta-aminolevulinic acid assay and for impurities in drug formulation.     

Fluorimetric determination of hepatic delta-aminolevulinic acid synthase activity by high-performance liquid chromatography

A fluorimetric method for measuring the activity of delta-aminolevulinic acid synthase (ALAS) in the liver of mice has been developed. The liver homogenate was used as the enzyme source. The final concentration of glycine (substrate) used for the assay was 100 mM. The delta-aminolevulinic acid (ALA) formed during incubation was converted into a highly fluorescent derivative by condensation with acetylactone and formaldehyde (application of the Hantzsch reaction). This derivative was completely separated from other fluorescent substances in the reaction medium, and it was determined using a high-performance liquid chromatograph equipped with a fluorescence monitor (370/460 nm). The activity of ALAS was expressed as nmol ALA formed per gram liver per hour.     

Synthesis and Reactivity of Porphyrin Complexes of Group IV p-Elements

The composition of products and the general regularities of complex formation of meso-tetraphenylporphine with Si(IV), Ge(IV), Sn(II), and Pb(II), as well as the kinetics and mechanism of dissociation of the resulting complexes under the action of proton-donor reagents were studied. The nature of chemical and steric factors that operate to stabilize mixed-ligand acido porphyrin p-metal complexes was revealed.     

Thermotropic homopolyesters. IV. Study of fiber formation

We report a melt spinning and viscosity study of two semiflexible homopolyesters containing both rigid and flexible segments in the repeating unit. Single filaments of the polyesters formed from 4,4′-diacetoxybiphenyl and azelaic acid (PB7) and sebacic acid (PB8), and from 4′-hydroxyphenyl-4-hydroxycinnamate and azelaic acid (C7), were spun at temperatures between 205 and 255°C. The temperature dependence of the Newtonian melt viscosity of PB7 and C7 was investigated, and a range of molecular weights was studied for PB7. The spinning parameters, fiber characteristics, and viscosity-temperature behavior are related to the type of mesophase formed. The mechanical properties of fibers spun from both the nematic and smectic phases of these semiflexible chain polymers were poor. Increasing the polymer molecular weight or extrusion rate only afforded a modest improvement in fiber properties. Most polymers could not be spun at temperatures corresponding to the existence of the single mesophase. Hence the low viscosity typical of the nematic mesophase is not necessarily an advantage in fiber formation from the melt. It appears from these results that this type of polyester does not possess adequate chain extension to develop ultrahigh-modulus properties. The director, which describes the local orientation of molecules within the mesophase, may undergo more frequent variations than is the case for rigid chain polyesters. Mechanisms relevant to flexible polymers may contribute to the development of orientation for this class of nematogenic melts.     

Extraction of iridium(IV) by dihexyl sulfoxide from hydrochloric acid solutions

The extraction of iridium(IV) by dihexyl sulfoxide from hydrochloric acid solutions was studied. Optimum conditions for the extraction of iridium(IV) were determined. It was found that an ion-association mechanism of iridium(IV) extraction took place in the test extraction systems at a phase contact time of 10 min. As the phase contact time was increased, the extraction took place by a mixed mechanism. One extractant molecule was incorporated into the inner coordination sphere of the iridium(IV) ion. This decreased the charge of the extracted complex to unity.     

六配位锇（IV）卟啉中的轴向配体效应

使用密度泛函理论和定性轨道分析方法研究了六配位锇(Ⅳ)叶啉络合物[Os(por)L_2](L=CH_3,OCH_3,SCH_3,SeCH_3,Cl,Br,I)中不同的轴向配体对络合物的结构和磁性的影响.结果表明,不同性质的轴向配体对锇的两个e_g轨道(即d_(xz)和d_(yz))的影响不同,导致锇具有不同的电子组态:(1)当轴向配体为反位影响很强的CH_3时,L—Os—L弯曲,这种弯曲导致d_(xz)和d_(yz)轨道能级分裂,整个络合物表现为弯曲抗磁;(2)当轴向配体为反位影响很弱的OCH_3,SCH_3,SeCH_3以及卤素Cl,Br,I时,L—Os—L均保持线性,其中单面π供体性较强的SCH_3,SeCH_3,使得d_(xz)和d_(yz),轨道能级有较大的分裂,络合物呈线性抗磁;单面π供体性较弱的OCH_3,其d_(xz)和d_(yz)轨道能级分裂较小,整个络合物呈线性顺磁;卤素则由于其双面π供体的等同性,使得它对d_(xz)和d_(yz)轨道的影响一样,其简并性仍得以保持,络合物也表现为线性顺磁.     

六配位锇（IV）卟啉中的轴向配体效应

使用密度泛函理论和定性轨道分析方法研究了六配位锇（IV）卟啉络合物[Os (por)L_2] (L = CH_3, OCH_3, SCH_3, SeCH_3, Cl, Br, I)中不同的轴向配体对 络合物的结构和磁性的影响。结果表明，不同性质的轴向配体对锇的两个e_g轨道 （即d_(xz)和d_(yz))的影响不同，导致锇具有不同的电子组态：（1）当铀当配体 为反位影响很强的CH_3时，L-Os-L弯曲，这种弯曲导致d_(xz)和d_(yz)转道能级分 裂，整个络合物表现为弯曲抗磁；（2）当轴向配体为反位影响很弱的OCH_3， SCH_3, SeCH_3以及卤素Cl, Br, I时L－Os-L均保持线性，其中单π供体性较强的 SCH_3，SeCH_3，使得d_(xz)和d_(yz)轨道能级有较大的分裂，络合物呈线性抗磁 ；单面π供体性较弱的OCH_3，其d_(xy)和d_(yz)轨道能级分裂较小，整个络合物 呈线性顺磁；卤素则由于其双面π供体的等同性，使得它对d_(xz)和d_(yz)轨道的 影响一样，其简并性仍得以保持，化合物也表现为线性顺磁。     

Detection of delta-aminolevulinic acid, porphobilinogen and porphyrins related to heme biosynthesis by high-performance liquid chromatography

Two new high-performance liquid chromatographic methods are described for the quantitative determination of porphyrins and their precursors. In our method, sub-nanomole quantities of porphyrins, delta-aminolevulinic acid and porphobilinogen derivatized with ophthalaldehyde were injected onto a C18 reversed-phase column and eluted with 0.1 M monobasic sodium phosphate-methanol-tetrahydrofuran (4:6:3) and detected with a spectrofluorometer. A second reversed-phase system using methanol-tetrahydrofuran-22 mM acetate buffer (15:6:11) was also developed.     

Multifunctional acid formation from the gas-phase ozonolysis of beta-pinene

The gas-phase ozonolysis of beta-pinene was studied in static chamber experiments, using gas chromatography coupled to mass spectrometric and flame ionisation detection to separate and detect products. A range of multifunctional organic acids-including pinic acid, norpinic acid, pinalic-3-acid, pinalic-4-acid, norpinalic acid and OH-pinalic acid-were identified in the condensed phase after derivatisation. Formation yields for these products under systematically varying reaction conditions (by adding different OH radical scavengers and Criegee intermediate scavengers) were investigated and compared with those observed from alpha-pinene ozonolysis, allowing detailed information on product formation mechanisms to be elucidated. In addition, branching ratios for the initial steps of the reaction were inferred from quantitative measurements of primary carbonyl formation. Atmospheric implications of this work are discussed.     

In vitro fluorescence, toxicity and phototoxicity induced by delta-aminolevulinic acid (ALA) or ALA-esters

Synthesis of delta-aminolevulinic acid (ALA) derivatives is a promising way to improve the therapeutic properties of ALA, particularly cell uptake or homogeneity of protoporphyrin IX (PpIX) synthesis. The fluorescence emission kinetics and phototoxic properties of ALA-n-pentyl ester (E1) and R,S-ALA-2-(hydroxymethyl) tetrahydrofuranyl ester (E2) were compared with those of ALA and assessed on C6 glioma cells. ALA (100 micrograms/mL), E1 and E2 (10 micrograms/mL) induced similar PpIX-fluorescence kinetics (maximum between 5 and 7 h incubation), fluorescence being limited to the cytoplasm. The 50% lethal dose occurred after 6 h with 45, 4 and 8 micrograms/mL of ALA, E1 and E2, respectively. ALA, E1 and E2 induced no dark toxicity when drugs were removed after 5 min of incubation. However, light (25 J/cm2) applied 6 h after 5 min incubation with 168 micrograms/mL of each compound induced 85% survival with ALA, 27% with E1 and 41% with E2. Increasing the incubation time with ALA, E1 and E2 before washing increased the phototoxicity, but E1 and E2 remained more efficient than ALA, regardless of incubation time. ALA-esters were more efficient than ALA in inducing phototoxicity after short incubation times, probably through an increase of the amount of PpIX synthesized by C6 cells.     

Recognition-induced supramolecular porous nanosphere formation from cyclodextrin conjugated by cholic acid

A supramolecular porous nanosphere is constructed from amphiphilic cholic acid-modified cyclodextrin triggered by guest sodium 1-naphthylamino-4-sulfonate and is comprehensively characterized by nuclear magnetic resonance (NMR), light scattering, transmission electron microscopy, and gas adsorption experiments. The results obtained show that the porous nanosphere with the radius of 25-35 nm has moderate nitrogen adsorption ability. Further NMR, circular dichroism, and the fluorimetric titrations on the self-assembling behavior in aqueous solution reveal that the substituting group of the guest molecule and pH values are the key to induce the formation of the porous nanosphere.