Main Transformation Products Research Articles

Analysis of the ozonation of 2-mercaptobenzothiazole in water and tannery wastewater using sum parameters, liquid- and gas chromatography and capillary electrophoresis

2-Mercaptobenzothiazole (MBT) is known as a widespread, toxic and poorly biodegradable pollutant. In this study, MBT has been ozonated in pure water and in spiked tannery wastewater at various pH-values to investigate its oxidative destruction. All oxidation tests performed similarly concerning the sequence of occurrence of the main transformation products. MBT and its breakdown products showed a high affinity towards ozone as indicated by the rates for partial oxidation and mineralization. Using HPLC–DAD, benzothiazole was identified as the first ozonation product, reaching up to 60 mol% of the original MBT-concentration, followed by low concentrations of 2(3H)-benzothiazolone. Only small amounts of additional hydroxybenzothiazoles have been found by GC/MS. In all tests, a compound with the sum formula of benzothiazol-2-sulfonate (BTSO 3) proved to be a main transformation product. IR-, NMR-, UV- and MS-spectra were highly similar to pure BTSO 3. However, benzothiazole-2-sulfite is proposed as the correct structure since a slow hydrolysis reaction occurred and HPLC-retention times were different by comparison with BTSO 3. By further ozonation, 7 organic and 3 inorganic anions have been identified using capillary electrophoresis with indirect UV detection. In conclusion, MBT is readily transformed by ozonation and, thus, wastewaters containing high amounts of MBT should easily be detoxified using ozone.

Lignans from the roots of Urtica dioica and their metabolites bind to human sex hormone binding globulin (SHBG).

Polar extracts of the stinging nettle (Urtica dioica L.) roots contain the ligans (+)-neoolivil, (-)-secoisolariciresinol, dehydrodiconiferyl alcohol, isolariciresinol, pinoresinol, and 3,4-divanillyltetrahydrofuran. These compounds were either isolated from Urtica roots, or obtained semisynthetically. Their affinity to human sex hormone binding globulin (SHBG) was tested in an in vitro assay. In addition, the main intestinal transformation products of plant lignans in humans, enterodiol and enterolactone, together with enterofuran were checked for their activity. All lignans except (-)-pinoresinol developed a binding affinity to SHBG in the in vitro assay. The affinity of (-)-3,4-divanillyltetrahydrofuran was outstandingly high. These findings are discussed with respect to potential beneficial effects of plant lignans on benign prostatic hyperplasia (BPH).

Transformation of 1,1,1-trichloroethane in an anaerobic packed-bed reactor at various concentrations of 1,1,1-trichloroethane, acetate and sulfate

Biotransformation of 1,1,1-trichloroethane (CH3CCl3) was observed in an anaerobic packed-bed reactor under conditions of both sulfate reduction and methanogenesis. Acetate (1 mM) served as an electron donor. CH3CCl3 was completely converted up to the highest investigated concentration of 10 μM. 1,1-Dichloroethane and chloroethane were found to be the main transformation products. A fraction of the CH3CCl3 was completely dechlorinated via an unknown pathway. The rate of transformation and the transformation products formed depended on the concentrations of CH3CCl3, acetate and sulfate. With an increase in sulfate and CH3CCl3 concentrations and a decrease in acetate concentration, the degree of CH3CCl3 dechlorination decreased. Both packed-bed reactor studies and batch experiments with bromoethanesulfonic acid, an inhibitor of methanogenesis, demonstrated the involvement of methanogens in CH3CCl3 transformation. Batch experiments with molybdate showed that sulfate-reducing bacteria in the packed-bed reactor were also able to transform CH3CCl3. However, packed-bed reactor experiments indicated that sulfate reducers only had a minor contribution to the overall transformation in the packed-bed reactor.

Transformation of carbon tetrachloride under sulfate reducing conditions.

The removal of carbon tetrachloride under sulfate reducing conditions was studied in an anaerobic packed-bed reactor. Carbon tetrachloride, up to a concentration of 30 microM, was completely converted. Chloroform and dichloromethane were the main transformation products, but part of the carbon tetrachloride was also completely dechlorinated to unknown products. Gram-positive sulfate-reducing bacteria were involved in the reductive dechlorination of carbon tetrachloride to chloroform and dichloromethane since both molybdate, an inhibitor of sulfate reduction, and vancomycin, an inhibitor of gram-positive bacteria completely inhibited carbon tetrachloride transformation. Carbon tetrachloride transformation by these bacteria was a cometabolic process and depended on the input of an electron donor and electron acceptor (sulfate). The rate of carbon tetrachloride transformation by sulfate reducing bacteria depended on the type of electron donor present. A transformation rate of 5.1 nmol x ml(-1) x h(-1) was found with ethanol as electron donor. At carbon tetrachloride concentrations higher than 18 microM, sulfate reduction and reductive dechlorination of carbon tetrachloride decreased and complete inhibition was observed at a carbon tetrachloride concentration of 56.6 microM. It is not clear what type of microorganisms were involved in the observed partial complete dechlorination of carbon tetrachloride. Sulfate reducing bacteria probably did not play a role since inhibition of these bacteria with molybdate had no effect on the complete dechlorination of carbon tetrachloride.

Pregnenolone and dehydroepiandrosterone as precursors of native 7-hydroxylated metabolites which increase the immune response in mice

Dehydroepiandrosterone (DHEA) and pregnenolone (PREG) were both metabolized by homogenates of brain, spleen, thymus, perianal skin, ventral skin, intestine, colon, coecum and muscle tissues from mice. The use of 2H-labeled substrates and of the twin ion technique of gas chromatography- mass spectrometry permitted identification of 7α-hydroxy-DHEA and of 5-androsterone-3β,17β-diol as DHEA metabolites in digests of all tissues. The extent of PREG metabolism was much lower than for DHEA with all tissues but amounts of the main transformation product were sufficient in brain, spleen and ventral skin digests for identification with 7α-hydroxy-PREG. Dimethylsulfoxide (DMSO) solutions of DHEA, PREG and of their 7-hydroxylated metabolites were injected at different doses and time intervals prior to proximal subcutaneous administration of a lysozyme antigen. Quantities of anti-lysozyme IgG were measured in the serum of treated mice and compared with that from sham-treated animals. Increase of anti-lysozyme IgG was obtained with DHEA and PREG (1g/kg) when injected 2 h prior to lysozyme. Much lower doses (160 times less) of 7α-hydroxy- DHEA and -PREG were also found to be significantly active when administered at the moment of lysozyme injection. A larger dose of 7β-hydroxy-DHEA (50 mg/kg) was necessary for a similar effect. These results suggest that in tissues where immune response takes place, the locally-produced 7-hydroxy metabolites of PREG and DHEA are involved in a process which may participate in the physiological regulation of the body's immune response.

In vitro transformation of the tremorgenic mycotoxin verruculogen

A quantity of 50 mg of crystalline verruculogen was prepared from batch cultures ofAspergillus fumigatus for the use in thein vitro studies with S-9 liver fractions, feces suspensions, and cultures ofEscherichia coli.Incubation of verruculogen with S-9 liver fractions from swine resulted in the transformation of the parent compound into TR-2 toxin and 3 other more polar.TR-2 toxin was also shown to be the main transformation product when incubat-ing verruculogen with fecal suspensions or pure cultures ofE. coli (0149: K88). Incubation times of more than 2 hours led to a complete degradation of verruculogen as well as TR -2 toxin.

Kinetics of the reaction of superoxide anion-radical with olefins

Kinetic investigation of the reaction of electrochemically generated\(0_2 ^{\mathop - \limits_ \bullet } \) with perfluorooctene, styrene, and cyclohexene in acetonitrile, in the presence of tetraethylammonium perchlorate used as a background electrolyte, revealed that\(0_2 ^{\mathop - \limits_ \bullet } \) reacts with styrene and perfluorooctene at the double bond, and the reactivity of the olefins with respect to\(0_2 ^{\mathop - \limits_ \bullet } \) decreases with decrease in the electrophilicity of the substituents at the double bond: perfluorooctene > styrene > cyclohexene. The main transformation products of styrene are phthalic and benzoic acid esters.

Verhal ten von 3,4- Dichloranilin in wachsenden Pilzkul turen

3,4- Dichloraniline is being transformed by the white rot fungi Pleurotus ostreatus and Phanerochaete chrysosporium in subinhibitory concentrations up to 90%. Detailled tests with P . chrysosporium are indicating in contrast to previous reports that the fungus is not able to mineralize this aniline. The corresponding acylanilides from acetic-,succinic-,and hydroxyglutaric acid are being observed as main transformation products.

Microbial transformation studies on arteannuin B.

The microbial transformation of the sesquiterpene lactone arreannuin B [3] using Aspergillus flavipes produced dihydroarteannuin B [4] as the main transformation product. Preparative-scale fermentation of 3 with Beauveria bassiana, on the other hand, has resulted in the production of two metabolites, 3 beta-hydroxyarteannuin B [5] and 13-hydroxy-11-epi-dihydroarteannuin B [6]. The structure of these metabolites, all of which are new compounds, was established using chemical and spectroscopic techniques. The isomeric dihydrocompound, 11-epi-dihydroarteannuin B [7] and an isomer of arteannuin B [8] were also prepared chemically. All compounds were subjected to 2D-nmr experiments and full 1H- and 13C-nmr assignments were made.

Bacteriochlorophyll g. A new bacteriochlorophyll from Heliobacterium chlorum

A new bacteriochlorophyll g has been isolated from Heliobacterium chlorum. Its visible absorption spectrum is different from those of all other known bacteriochlorophylls, and it is extremely sensitive to oxygen in the presence of light. A proposal for the structure of the new bacteriochlorophyll g is given on the basis of absorption, CD, and 1H-NMR spectra of the corresponding bacteriopheophytin g and two main transformation products of Bchl g.

Transformations o f 1,5-hexadiene and 1,3,5-hexatriene on aluminum, gallium, and indium oxides

1. On the example of the transformations of 1,5-hexadiene at 450 and 520°, and of 1,3,5-hexatriene at 300 and 450°, on aluminum, gallium, and indium oxides it was shown that Al2O3 has a very weak, while Ga2O3 and In2O3 have a strong aromatizing (dehydrogenating) ability, but one that is less than that of Cr2O3. All three oxides catalyze migration of the double bond in dienic hydrocarbons. The main transformation products of 1,5-hexadiene are benzene and hexadienes, which are isomeric with the starting material, and benzene and cyclohexadienes in the case of 1,3,5-hexatriene. Hydrogenation products are also formed, as well as small amounts of hydrocarbons with a five-membered ring. 2. The obtained results can be explained by the fact that the formation of benzene from aliphatic C6 hydrocarbons on Ga2O3 and In2O3 proceeds by the same scheme as on other oxide catalysts. 3. The change in the aromatizing (dehydrogenation) ability when going from Al2O3 to Ga2O3 and In2O3 correlates with their ability to be reduced and is opposite to the change in the heats of formation of these oxides.

The determination of the transformation products of epoxides used in the heat stabilization of poly(vinyl chloride)

Methyl 9, 10-epoxyoctadecanoate has been used as a model compound to study the mode of action of epoxides when employed in the stabilization of poly(vinyl chloride) (PVC). Sheets of PVC containing 2% radioactively labelled methyl (1-[ 14C]) 9,10-epoxyoctadecanoate (both with and without calcium/zinc stearate) were prepared on a hydraulic press and subsequently heated in an oven for various times to simulate heat processing. The polymer was separated from the low molecular weight components by steric exclusion chromatography, the extent of bonding of epoxide to the polymer being monitored by the [ 14C] activity of the high molecular weight fraction, and the level of residual methyl 9,10-epoxyoctadecanoate being determined colorimetrically on the basis of the epoxide concentration. The main transformation product was identified by combined gas chromatography-mass spectrometry as the methyl 9,10-chlorohydroxyoctadecanoate which was subsequently quantified after suitable derivatization by electron capture gas chromatography. A direct correlation was shown between the loss of epoxide and the extent of heat processing but this loss could not be fully accounted for on the basis of the estimated levels of chlorohydrins.

Microbial transformation of antibiotics. IV. Transformation of maridomycin III by maridomycin III-insensitive streptomycetes.

Transformation of maridomycin III, a macrolide antibiotic, by maridomycin (MDM) III-insensitive streptomycetes was examined. Three main transformation products were obtained. In comparison with authentic samples, these transformation products were identified as 18-dihydro MDM III, 4′′-depropionyl MDM III and 18-dihydro-4′′-depropionyl MDM III. Reduction of the C–18 position of the macro lactone moiety of the antibiotic was thought to be a detoxication mechanism of the antibiotic by these insensitive strains.

Daily Elimination of Fecal Neutral Sterols by Humans

A study was made of the daily elimination of fetal neutral sterols in 22 healthy subjects and the average proportions of the main sterols were established. These were cholesterol (9.5%), its main bacterial transformation products: coprostanol (65%) and coprostanone (less than 6%), cholestanol (less than 2%), delta7-cholestenol (less than 2%) and phytosterols (18%). Epicoprostanol, which indicates a secondary mean of bacterial degradation of cholesterol has been searched for systematically. In general, traces only are present but in one case it amounts to more than 8% of the neutral sterols. The bulk of neutral sterols eliminated daily is very variable for different subjects and also for a same subject, although the concentration of fecal sterols is relatively constant (6.37 +/- 0.36 mg of sterols/g of feces). For a given subject under controlled diet conditions, differences in fecal elimination of sterols can essentially be ascribed to irregularity of digestive transit.

Transformation of steroids by Mucor griseo-cyanus.

Spores and vegetative growth of Mucor griseo-cyanus (ATCC 1207) hydroxylated deoxycorticosterone, testosterone, progesterone, and androst-4-ene-3,17-dione mainly to their 14α-hydroxy derivatives. However, with 17α-methyl substituted steroids, the main transformation products were the 7α-hydroxy derivatives.

Comparative metabolism in vivo of [4- 14C]cortisol in synovial fluid in the normal, rheumatoid and osteoarthritic knee

Ten min after the injection of [4- 14C]cortisol in the synovial cavity of normal and arthritic knees of humans and horses, a sample of synovial fluid was aspirated, extracted with organic solvents, and fractionated into free and conjugated fractions. The free fraction accounted for 85% of the total extract of the normal synovium of humans and horses while in the arthritic knees this fraction amounted to 93 and 96% of the total radioactivity in synovial fluid extract. The radioactivity which corresponded to unconverted cortisol was 44 and 47% of the total radiometabolites in synovium of normal knees of human and horse, respectively, 80% in a human subject with rheumatoid arthritis, 6% and 1% in human and horse with osteoarthritis. The main transformation product of cortisol in human and horse in normal and arthritic joints was 11β-hydroxyandrostenedione. 11-Ketoandrostenedione and less polar metabolites were isolated. Unidentified highly polar metabolites were also detected. The relatively small percentage of radioactivity which corresponded to cortisol in osteoarthritic human and horse was accompanied by a considerable increase in the radioactivity which corresponded mainly to 11β-hydroxyandrostenedione. After 10-min intervals up to 2 h the quantities of cortisol metabolites are changeable. After 2 h, the percentage of 11β-hydroxyandrostenedione, 11-ketoandrostenedione and less polar metabolites decreased considerably while the percentage of compounds of greater polarity than cortisol increased.