Instability of St. John's wort (Hypericum perforatum L.) and degradation of hyperforin in aqueous solutions and functional beverage

Several bioactive botanicals including St. John's wort (SJW; Hypericum perforatum L.) have been used to formulate functional foods and beverages. This study aimed to investigate the stability of SJW components in aqueous solutions and fruit-flavored drinks. Changes of active marker components (hypericin, pseudohypericin, hyperforin, and adhyperforin) as affected by pH and light exposure were determined by HPLC, and the degradation of hyperforin was analyzed by LC-MS/MS and NMR. SJW components were found to be unstable in acidic aqueous solutions. More changes occurred under light exposure, with hyperforin and adhyperforin decreasing the most. Less severe changes were observed in the drink sample as compared to the pH 2.65 solution. Major degradation products of hyperforin in acidic aqueous solutions were identified as furohyperforin, furohyperforin hydroperoxide, and furohyperforin isomer a. The latter was also found in the drink product containing SJW as an ingredient. Biological activities and potential quality and safety implications of these chemical changes are yet to be evaluated.

Rapid Biomonitoring of Heterocyclic Aromatic Amines in Human Urine by Tandem Solvent Solid Phase Extraction Liquid Chromatography Electrospray Ionization Mass Spectrometry

A rapid and facile tandem solvent solid phase extraction method was established to isolate the heterocyclic aromatic amines (HAAs) 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, and 2-amino-9H-pyrido[2,3-b]indole from urine. The HAAs were separated by reversed phase liquid chromatography and quantified by electrospray ionization tandem mass spectrometry (ESI/MS/MS) using selected reaction monitoring. The limits of detection and quantitation of these HAAs approached 1-3 and 2-8 pg/mL, respectively, using only 0.3 mL of urine for analysis. Full product ion spectra were acquired to corroborate analyte identities. The pretreatment of urine from human volunteers that had consumed a grilled beef meal with acid or base at 70 degrees C increased the concentration of HAAs by as much as 6-fold, indicating the presence of phase II conjugates of the parent compounds. HAAs containing an N-methylimidazole moiety undergo facile cleavage of the N-methyl group under collision-induced dissociation conditions, and MS/MS analysis in the constant neutral loss scan mode monitoring the transition [M + H](+) --> [M + H - CH(3)(*)](+) revealed the presence of two other HAAs. 2-Amino-3-methylimidazo[4,5-f]quinoxaline (IQx) was identified by coelution of the analyte with synthetic IQx and by acquisition of the product ion spectrum. The second HAA was present in a relatively high abundance in urine. The molecule had the same nominal mass as 8-MeIQx (MH(+) at m/z 214), and the product ion spectrum was similar to that of 8-MeIQx. This novel HAA was also found in the grilled meat consumed by the volunteers at a concentration of 8 parts per billion. The accurate mass measurement and product ion spectrum of this molecule by ESI quadrupole time-of-flight mass spectrometry revealed that it was an isomer of 8-MeIQx. This tandem solvent solid phase extraction LC/ESI/MS/MS procedure may be used to rapidly assess the daily exposure to a variety of HAAs in urine.

Degradation of benzo[a]pyrene by Mycobacterium vanbaalenii PYR-1

Metabolism of the environmental pollutant benzo[a]pyrene in the bacterium Mycobacterium vanbaalenii PYR-1 was examined. This organism initially oxidized benzo[a]pyrene with dioxygenases and monooxygenases at C-4,5, C-9,10, and C-11,12. The metabolites were separated by reversed-phase high-performance liquid chromatography (HPLC) and characterized by UV-visible, mass, nuclear magnetic resonance, and circular dichroism spectral analyses. The major intermediates of benzo[a]pyrene metabolism that had accumulated in the culture media after 96 h of incubation were cis-4,5-dihydro-4,5-dihydroxybenzo[a]pyrene (benzo[a]pyrene cis-4,5-dihydrodiol), cis-11,12-dihydro-11,12-dihydroxybenzo[a]pyrene (benzo[a]pyrene cis-11,12-dihydrodiol), trans-11,12-dihydro-11,12-dihydroxybenzo[a]pyrene (benzo[a]pyrene trans-11,12-dihydrodiol), 10-oxabenzo[def]chrysen-9-one, and hydroxymethoxy and dimethoxy derivatives of benzo[a]pyrene. The ortho-ring fission products 4-formylchrysene-5-carboxylic acid and 4,5-chrysene-dicarboxylic acid and a monocarboxylated chrysene product were formed when replacement culture experiments were conducted with benzo[a]pyrene cis-4,5-dihydrodiol. Chiral stationary-phase HPLC analysis of the dihydrodiols indicated that benzo[a]pyrene cis-4,5-dihydrodiol had 30% 4S,5R and 70% 4R,5S absolute stereochemistry. Benzo[a]pyrene cis-11,12-dihydrodiol adopted an 11S,12R conformation with 100% optical purity. The enantiomeric composition of benzo[a]pyrene trans-11,12-dihydrodiol was an equal mixture of 11S,12S and 11R,12R molecules. The results of this study, in conjunction with those of previously reported studies, extend the pathways proposed for the bacterial metabolism of benzo[a]pyrene. Our study also provides evidence of the stereo- and regioselectivity of the oxygenases that catalyze the metabolism of benzo[a]pyrene in M. vanbaalenii PYR-1.

Synthesis and investigation of alpha-hydroxy-N,N-didesmethyltamoxifen as a proximate carcinogen in the metabolic activation of tamoxifen

Tamoxifen is an adjuvant chemotherapeutic agent for the treatment of breast cancer and a chemoprotective agent for breast cancer prevention. Despite being beneficial in regard to breast cancer, tamoxifen is known to increase the risk of endometrial cancer and thromboembolic events in women; in addition, it induces liver tumors in rats and endometrial tumors in rats and mice. Tamoxifen and its metabolite, N-desmethyltamoxifen, are metabolically activated to DNA binding electrophiles through alpha-hydroxylation, followed by O-esterification, primarily via sulfation. In the present study, we have investigated whether a second desmethylated metabolite of tamoxifen, N,N-didesmethyltamoxifen, is also involved in the metabolic activation of this antiestrogen to a genotoxic species. Alpha-hydroxy-N,N-didesmethyltamoxifen was synthesized, further activated by sulfation, and then reacted with DNA. After enzymatic hydrolysis to deoxynucleosides, HPLC analysis indicated the formation of one major DNA adduct, which was characterized as (E)-alpha-(deoxyguanosin-N(2)-yl)-N,N-didesmethyltamoxifen. Using (32)P-postlabeling, in combination with HPLC, the same adduct was detected in liver DNA from rats treated intraperitoneally with alpha-hydroxy-N,N-didesmethyltamoxifen. In contrast, only a low extent of adduct formation could be found in rats administered N,N-didesmethyltamoxifen. These data indicate that although alpha-hydroxy-N,N-didesmethyltamoxifen can be converted to a genotoxin in rat liver, this pathway is a minor one in the metabolic activation of tamoxifen.

Identification of aminobiphenyl derivatives in commercial hair dyes

A recent epidemiological study suggested that aromatic amines present in hair dyes may contribute to an increased risk of bladder cancer (Gago-Dominguez, et al. (2003) Carcinogenesis 24, 483-489). Moreover, a preliminary study linked frequent hair dye usage with elevated levels of DNA adducts of 4-aminobiphenyl (4-ABP) in human epithelial breast cells (Gorlewska, et al. Proc. Am. Assoc. Cancer Res. 43, 1018-1019). Therefore, we sought to determine if 4-ABP, a recognized human urinary bladder carcinogen, is present in commercial hair dyes. 4-ABP was isolated from dyes by solvent extraction with hexane, followed by silica gel chromatography, either with or without chemical treatment of the extract with Zinc/HCl, and a final purification with a mixed cation exchange reversed-phase resin. The identity of 4-ABP was confirmed by both HPLC with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) and gas chromatography with negative ion chemical ionization mass spectrometry (GC-NICI-MS) following chemical derivatization with pentafluoropropionic anhydride (PFPA). The levels of 4-ABP ranged from not detectable (<0.29 parts per billion (ppb)) up to 12.8 ppb. The noncarcinogenic isomer 2-aminobiphenyl (2-ABP) was also found at quantities up to 310 ppb. 4-ABP was detected in eight of the 11 hair dyes and found in black, red, and blonde hair dyes but not in brown hair dyes. 1,4-Phenylenediamine (PPD) is a key constituent for color development of many permanent hair dyes. Some batches of chemical research grade PPD were contaminated with 4-ABP (up to 500 ppb) and 2-ABP (up to 70 parts per million) and may be a source of ABP contamination in hair dyes. These analytical data demonstrate that 4-ABP is present in some hair dyes. Studies on dermal absorption and bioavailability of 4-ABP from hair dyes are required to determine if this aromatic amine contributes to the increased risk of bladder cancer reported in frequent users of hair dyes.

Regio- and stereoselective metabolism of 7,12-dimethylbenz[a]anthracene by Mycobacterium vanbaalenii PYR-1

The degradation of 7,12-dimethylbenz[a]anthracene (DMBA), a carcinogenic polycyclic aromatic hydrocarbon, by cultures of Mycobacterium vanbaalenii PYR-1 was studied. When M. vanbaalenii PYR-1 was grown in the presence of DMBA for 136 h, high-pressure liquid chromatography (HPLC) analysis showed the presence of four ethyl acetate-extractable compounds and unutilized substrate. Characterization of the metabolites by mass and nuclear magnetic resonance spectrometry indicated initial attack at the C-5 and C-6 positions and on the methyl group attached to C-7 of DMBA. The metabolites were identified as cis-5,6-dihydro-5,6-dihydroxy-7,12-dimethylbenz[a]anthracene (DMBA cis-5,6-dihydrodiol), trans-5,6-dihydro-5,6-dihydroxy-7,12-dimethylbenz[a]anthracene (DMBA trans-5,6-dihydrodiol), and 7-hydroxymethyl-12-methylbenz[a]anthracene, suggesting dioxygenation and monooxygenation reactions. Chiral stationary-phase HPLC analysis of the dihydrodiols showed that DMBA cis-5,6-dihydrodiol had 95% 5S,6R and 5% 5R,6S absolute stereochemistry. On the other hand, the DMBA trans-5,6-dihydrodiol was a 100% 5S,6S enantiomer. A minor photooxidation product, 7,12-epidioxy-7,12-dimethylbenz[a]anthracene, was also formed. The results demonstrate that M. vanbaalenii PYR-1 is highly regio- and stereoselective in the degradation of DMBA.

Quantification of tamoxifen DNA adducts using on-line sample preparation and HPLC-electrospray ionization tandem mass spectrometry

The nonsteroidal antiestrogen tamoxifen is used as an adjuvant chemotherapeutic agent for the treatment of all stages of hormone-dependent breast cancer and more recently as a chemopreventive agent in women with elevated risk of developing the disease. While clearly beneficial for the treatment of breast cancer, tamoxifen has been reported to increase the risk of endometrial cancer in women. Furthermore, it has been shown to be hepatocarcinogenic in rats. Tamoxifen is clearly genotoxic in rat liver, as indicated by the formation of DNA adducts; the occurrence of tamoxifen DNA adducts in human endometrial tissue is more controversial. The detection and quantitation of tamoxifen DNA adducts have relied primarily upon (32)P-postlabeling, with other techniques, such as immunoassays and accelerator mass spectrometry, being used to a much lesser extent. To expand the range of available analytical methodologies for quantifying tamoxifen DNA adducts, we have developed an assay using on-line sample preparation, coupled with HPLC and electrospray ionization tandem mass spectrometry (ES-MS/MS). alpha-Acetoxytamoxifen was reacted with salmon testis DNA at ratios between 0.1 ng and 1 mg alpha-acetoxytamoxifen per mg DNA. After enzymatic hydrolysis to nucleosides, the most highly modified DNA samples were analyzed by HPLC-UV, which indicated the presence of two adduct peaks in approximately a 1:4 ratio. The major adduct was isolated, rigorously characterized as (E)-alpha-(deoxyguanosin-N(2)-yl)tamoxifen, and quantified on the basis of its molar extinction coefficient. A similar reaction was conducted with [N(CD(3))(2)]-alpha-acetoxytamoxifen to prepare a deuterated adduct that could serve as an internal standard for ES-MS/MS. The limit of detection for the HPLC-ES-MS/MS method was approximately 5 adducts/10(9) nucleotides, with an intra- and interassay precision of 3% relative standard deviation. The method was validated over the range of 8-1 520,000 adducts/10(8) nucleotides using 100 microg samples of DNA modified in vitro. Analysis of liver DNA from female Sprague-Dawley rats treated by gavage with seven daily doses of 20 mg tamoxifen/kg body weight gave a value of 496 +/- 16 adducts/10(8) nucleotides for (E)-alpha-(deoxyguanosin-N(2)-yl)tamoxifen and 626 +/- 18 adducts/10(8) nucleotides for (E)-alpha-(deoxyguanosin-N(2)-yl)-N-desmethyltamoxifen. These data indicate that the HPLC-ES-MS/MS methodology has sufficient sensitivity and precision to be useful in the analysis of tamoxifen DNA adducts formed in vivo in experimental models and may be able to detect tamoxifen DNA adduct formation in human tissue samples.

Biotransformation of mirtazapine by Cunninghamella elegans

The fungus Cunninghamella elegans was used as a microbial model of mammalian metabolism to biotransform the tetracyclic antidepressant drug mirtazapine, which is manufactured as a racemic mixture of R(-)- and S(+)-enantiomers. In 168 h, C. elegans transformed 91% of the drug into the following seven metabolites: 8-hydroxymirtazapine, N-desmethyl-8-hydroxymirtazapine, N-desmethylmirtazapine, 13-hydroxymirtazapine, mirtazapine N-oxide, 12-hydroxymirtazapine, and N-desmethyl-13-hydroxymirtazapine. Circular dichroism spectral analysis of unused mirtazapine indicated that it was slightly enriched with the R(-)-enantiomer. When the fungus was treated with the optically pure forms of the drug, the S(+)-enantiomer produced all seven metabolites whereas the R(-)-enantiomer produced only 8-hydroxymirtazapine, N-desmethyl-8-hydroxymirtazapine, N-desmethylmirtazapine, and mirtazapine N-oxide. C. elegans produced five mammalian and two novel metabolites and is therefore a suitable microbial model for mirtazapine metabolism.

Transformation of cinoxacin by Beauveria bassiana

The ability of the fungus Beauveria bassiana ATCC 7159 to transform the antibacterial agent cinoxacin was investigated. Cultures in sucrose-peptone broth were dosed with cinoxacin, grown for 20 days, and then extracted with ethyl acetate. Two metabolites were detected and purified by high-performance liquid chromatography. The major metabolite was identified by mass and proton nuclear magnetic resonance spectra as 1-ethyl-1,4-dihydro-3-(hydroxymethyl)[1,3]dioxolo[4,5-g]cinnolin-4-one and the minor metabolite was identified as 1-ethyl-1,4-dihydro-6,7-dihydroxy-3-(hydroxymethyl)cinnolin-4-one. B. bassiana also reduced quinoline-3-carboxylic acid to 3-(hydroxymethyl)quinoline.

Isolation of an anaerobic intestinal bacterium capable of cleaving the C-ring of the isoflavonoid daidzein

Colonic bacteria were screened for bacteria involved in the conversion of phytoestrogens. A gram-positive anaerobic bacterium, strain HGH 136, capable of conversion of the isoflavonoid daidzein, was isolated and identified as a Clostridium sp. The bacterium cleaved the C-ring of daidzein to produce O-demethylangolensin ( O-Dma). This compound was identified by comparison of the HPLC retention time and UV spectrum of the metabolite with chemically synthesized O-Dma. The identity of the metabolite was confirmed by liquid chromatography-mass spectrometry and NMR using synthetic O-Dma as a standard. The bacterium incubated with synthetic dihydrodaidzein also produced O-Dma. After 3 days of incubation, 28% of added daidzein and 12% of added dihydrodaidzein were converted to O-Dma. This is the first study in which an anaerobic bacterium involved in the ring cleavage of daidzein to produce O-Dma has been identified.

DNA adducts from nitroreduction of 2,7-dinitrofluorene, a mammary gland carcinogen, catalyzed by rat liver or mammary gland cytosol

Nitrofluorenes are mutagenic and carcinogenic environmental pollutants arising chiefly from combustion of fossil fuels. Nitro aromatic compounds undergo nitroreduction to N-hydroxy arylamines that bind to DNA directly or after O-esterification. This study analyzes the DNA binding and adducts from the in vitro nitroreduction of 2,7-dinitrofluorene (2,7-diNF), a potent mammary carcinogen in the rat. Potential adduct(s) of 2,7-diNF was (were) generated by reduction of 2-nitroso-7-NF with ascorbate/H(+) in the presence of calf thymus DNA. The major adduct was characterized by HPLC/ESI/MS and (1)H NMR spectrometry as N-(deoxyguanosin-8-yl)-2-amino-7-NF, and a minor one was determined by HPLC/ESI/MS to be a deoxyadenosine adduct of 2-amino-7-NF. Products from enzymatic nitroreduction were monitored by HPLC and DNA adduct formation by (32)P-postlabeling. Xanthine oxidase/hypoxanthine-catalyzed nitroreduction of 2,7-diNF, 2-nitrofluorene (2-NF), and 1-nitropyrene (1-NP) yielded the respective amines to similar extents (30-50%). However, the level of the major adducts ( approximately 0.15/10(6) nucleotides) from 2-NF [N-(deoxyguanosin-8-yl)-2-aminofluorene] and 2,7-diNF [N-(deoxyguanosin-8-yl)-2-amino-7-NF] was < or = 2% that from 1-NP. In the presence of acetyl CoA, nitroreduction of 2-NF catalyzed by rat liver cytosol/NADH yielded the same adduct at a level of 2.2/10(6) nucleotides. Liver or mammary gland cytosol with acetyl CoA yielded mainly N-(deoxyguanosin-8-yl)-2-amino-7-NF from 2,7-diNF at >30 adducts/10(6) nucleotides, levels comparable to those from 1,6-dinitropyrene and 4- or 49-fold greater than the respective levels without acetyl CoA. Recovery of 2-nitroso-7-NF and 2-amino-7-NF from cytosol-catalyzed reduction of 2,7-diNF indicated nitroreduction and an N-hydroxy arylamine intermediate. Likewise, the presence of 2-acetylamino-7-NF indicated that reactivity with acyltransferase(s) was not prevented by the nitro group at C7. These data are consistent with activation of 2,7-diNF via nitroreduction to the N-hydroxy arylamine and acetyl CoA-dependent O-acetylation of the latter to bind to DNA. Enzymatic nitroreduction of 2,7-diNF was greatly enhanced by 9-oxidation. The nitroreduction of either 9-oxo-2,7-diNF or 9-hydroxy-2,7-diNF catalyzed by liver cytosol with acetyl CoA yielded two adducts (>2/10(6) nucleotides). Differences in the TLC migration of these adducts, compared to those from 2,7-diNF, and the lack of 2,7-diNF formation in the incubations suggested retention of the C9-oxidized groups. The relative ratios of the amine to amide from nitroreductions of 9-oxo-2,7-diNF and 2,7-diNF catalyzed by liver cytosol suggested that the 9-oxo group decreased reactivity with acyltransferase and, thus, the amount of N-acetoxy arylamine that binds to DNA. The mammary gland tumorigenicity of 2,7-diNF and the extent of its activation by the tumor target tissue shown herein suggest relevance of this environmental pollutant for breast cancer.

Degradation of biphenyl by Mycobacterium sp. strain PYR-1

The metabolism of biphenyl by Mycobacterium sp. PYR-1 was investigated. The Mycobacterium sp. degraded >98% of the biphenyl added within 72 h. Analysis of ethyl acetate extracts of the culture medium by HPLC indicated that benzoic acid was the major metabolite. Other products were 4-hydroxybiphenyl, 4-hydroxybenzoic acid, and 5-oxo-5-phenylpentanoic acid. The metabolites were characterized by mass and 1H NMR spectrometry. Identification of benzoic acid and 5-oxo-5-phenylpentanoic acid indicates that biphenyl degradation by Mycobacterium sp. PYR-1 is generally similar to known pathways. A novel alternative metabolic pathway consisted of monooxygenation at C-4 of biphenyl to give 4-hydroxybiphenyl, with subsequent degradation via ring cleavage to 4-hydroxybenzoic acid.

Formation of conjugates from ciprofloxacin and norfloxacin in cultures of Trichoderma viride

The formation of conjugates from two antibacterial fluoroquinolone drugs, ciprofloxacin and norfloxacin, was observed in cultures of Trichoderma viride that had been grown in sucrose-peptone broth and extracted 16 d after dosing with the drugs. Both conjugates were purified by high-performance liquid chromatography and found to be optically active. They were identified by mass and proton nuclear magnetic resonance spectra as 4-hydroxy-3-oxo-4-vinylcyclopent-1-enyl ciprofloxacin and 4-hydroxy-3-oxo-4-vinylcyclopent-1-enyl norfloxacin. The transformation of veterinary fluoroquinolones in the presence of fungi may have ecological significance.

Oxidation of phenothiazine and phenoxazine by Cunninghamella elegans

1. To determine the ability of fungi to metabolize sulphur- and oxygen-containing azaarenes, Cunninghamella elegans ATCC 9245 was grown in 125-ml flasks containing fluid Sabouraud medium. The cultures and controls were incubated at 28 degrees C with shaking and dosed with 16.7 mM phenothiazine or phenoxazine. After incubation for 72h, the mycelia and filtrates were extracted with ethyl acetate and the combined residues analysed by high-performance liquid chromatography. Residual phenothiazine and phenoxazine were 21 and 22%, respectively, of the total UV absorbance at 254 nm. 2. The metabolites were identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. The fungus oxidized phenothiazine to phenothiazine sulphoxide, 3-hydroxyphenothiazine sulphoxide, phenothiazin-3-one, and 3-hydroxyphenothiazine and oxidized phenoxazine to phenoxazin-3-one. 3. Three of the four compounds produced by C. elegans from phenothiazine were identical to those produced by mammals, supporting the use of the fungus as a microbial model for drug metabolism.

Metabolism of anthracene by a Rhodococcus species

A Rhodococcus sp. isolated from contaminated river sediment was investigated to determine if the isolate could degrade high molecular mass polycyclic aromatic hydrocarbons. The Rhodococcus sp. was able to utilize anthracene (53%), phenanthrene (31%), pyrene (13%), and fluoranthene (5%) as sole source of carbon and energy, but not naphthalene or chrysene. In a study of the degradation of anthracene by a Rhodococcus sp., the identification of ring-fission products indicated at least two ring-cleavage pathways. One results in the production of 6,7-benzocoumarin, previously shown to be produced chemically from the product of meta cleavage of 1,2-dihydroxyanthracene, a pathway which has been well established in Gram-negative bacteria. The second is an ortho cleavage of 1,2-dihydroxyanthracene that produces 3-(2-carboxyvinyl)naphthalene-2-carboxylic acid, a dicarboxylic acid ring-fission product. This represents a novel metabolic pathway only identified in Gram-positive bacteria.

The fungus Pestalotiopsis guepini as a model for biotransformation of ciprofloxacin and norfloxacin

The metabolism of the fluoroquinolone drugs ciprofloxacin and norfloxacin by Pestalotiopsis guepini strain P-8 was investigated. Cultures were grown at 28 degrees C in sucrose/peptone broth for 18 days after dosing with ciprofloxacin (300 microM) or norfloxacin (313 microM). Four major metabolites were produced from each drug; and these were purified by high-performance liquid chromatography and identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. Ciprofloxacin metabolites included N-acetylciprofloxacin (52.0%), desethylene-N-acetylciprofloxacin (9.2%), N-formylciprofloxacin (4.2%), and 7-amino-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (2.3%). Norfloxacin metabolites included N-acetylnorfloxacin (55.4%), desethylene-N-acetylnorfloxacin (8.8%), N-formylnorfloxacin (3.6%), and 7-amino-1-ethyl-6-fluoro4-oxo-1,4-dihydroquinoline-3-carboxylic acid (2.1%). N-Formylciprofloxacin and the four transformation products from norfloxacin are all known to be mammalian metabolites.

Degradation of phenanthrene and anthracene by cell suspensions of Mycobacterium sp. strain PYR-1

Cultures of Mycobacterium sp. strain PYR-1 were dosed with anthracene or phenanthrene and after 14 days of incubation had degraded 92 and 90% of the added anthracene and phenanthrene, respectively. The metabolites were extracted and identified by UV-visible light absorption, high-pressure liquid chromatography retention times, mass spectrometry, (1)H and (13)C nuclear magnetic resonance spectrometry, and comparison to authentic compounds and literature data. Neutral-pH ethyl acetate extracts from anthracene-incubated cells showed four metabolites, identified as cis-1,2-dihydroxy-1,2-dihydroanthracene, 6,7-benzocoumarin, 1-methoxy-2-hydroxyanthracene, and 9,10-anthraquinone. A novel anthracene ring fission product was isolated from acidified culture media and was identified as 3-(2-carboxyvinyl)naphthalene-2-carboxylic acid. 6,7-Benzocoumarin was also found in that extract. When Mycobacterium sp. strain PYR-1 was grown in the presence of phenanthrene, three neutral metabolites were identified as cis- and trans-9,10-dihydroxy-9,10-dihydrophenanthrene and cis-3,4-dihydroxy-3,4-dihydrophenanthrene. Phenanthrene ring fission products, isolated from acid extracts, were identified as 2,2'-diphenic acid, 1-hydroxynaphthoic acid, and phthalic acid. The data point to the existence, next to already known routes for both gram-negative and gram-positive bacteria, of alternative pathways that might be due to the presence of different dioxygenases or to a relaxed specificity of the same dioxygenase for initial attack on polycyclic aromatic hydrocarbons.

Metabolism of the veterinary fluoroquinolone sarafloxacin by the fungus Mucor ramannianus

To investigate the microbial biotransformation of veterinary fluoroquinolones, Mucor ramannianus was grown in sucrose/peptone broth with sarafloxacin for 18 days. Cultures were extracted with ethyl acetate and extracts were analyzed by liquid chromatography. The two metabolites (26% and 15% of the A280, respectively) were identified by mass and 1H nuclear magnetic resonance spectra as N-acetylsarafloxacin and desethylene-N-acetylsarafloxacin. The biological formation of desethylene-N-acetylsarafloxacin has not been previously observed.

Use of 13C NMR spectrometric data to produce a predictive model of estrogen receptor binding activity

We have developed a spectroscopic data-activity relationship (SDAR) model based on 13C NMR spectral data for 30 estrogenic chemicals whose relative binding affinities (RBA) are available for the alpha (ERalpha) and beta (ERbeta) estrogen receptors. The SDAR models segregated the 30 compounds into strong and medium binding affinities. The SDAR model gave a leave-one-out (LOO) cross-validation of 90%. Two compounds that were classified incorrectly in the SDAR model were in the transition zone between classifications. Real and predicted 13C NMR chemical shifts were used with test compounds to evaluate the predictive behavior of the SDAR model. The 13C NMR SDAR model using predicted 13C NMR data for the test compounds provides a rapid, reliable, and simple way to screen whether a compound binds to the estrogen receptors.

Biotransformation of vinclozolin by the fungus Cunninghamella elegans

This study investigated the biotransformation of the dicarboximide fungicide vinclozolin [3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione] by the fungus Cunninghamella elegans. Experiments with phenyl-[U-ring-14C]vinclozolin showed that after 96 h incubation, 93% had been transformed to four major metabolites. Metabolites were separated by HPLC and characterized by mass and NMR spectroscopy. Biotransformation occurred predominantly on the oxazolidine-2,4-dione portion of vinclozolin. The metabolites were identified as the 3R- and 3S- isomers of 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutyranilide, N-(2-hydroxy-2-methyl-1-oxobuten-3-yl)-3,5-dichlorophenyl-1-carbamic acid, and 3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide. The enanilide compound has been reported previously as a plant and mammalian metabolite and is implicated to contain antiandrogenic activity. The 3R- and 3S- isomers of 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutyranilide are novel metabolites.

Isolation of human intestinal bacteria metabolizing the natural isoflavone glycosides daidzin and genistin

Fecal bacteria from a healthy individual were screened for the specific bacteria involved in the metabolism of dietary isoflavonoids. Two strains of bacteria capable of producing primary and secondary metabolites from the natural isoflavone glycosides daidzin and genistin were detected. The metabolites were identified by comparison of their HPLC/mass, 1H NMR and UV spectra with those of standard and synthetic compounds. Both Escherichia coli HGH21 and the gram-positive strain HGH6 converted daidzin and genistin to the their respective aglycones daidzein and genistein. Under anoxic conditions, strain HGH6 further metabolized the isoflavones daidzein and genistein to dihydrodaidzein and dihydrogenistein, respectively. The reduction of a double bond between C-2 and C-3 to a single bond was isoflavonoid-specific by strain HGH6, which did not reduce a similar bond in the flavonoids apigenin and chrysin. Strain HGH6 did not further metabolize dihydrodaidzein and dihydrogenistein. This is the first study in which specific colonic bacteria that are involved in the metabolism of daidzin and genistin have been detected.

(13)C NMR and electron ionization mass spectrometric data-activity relationship model of estrogen receptor binding

Two Spectroscopic Data-Activity Relationship (SDAR) models based on (13)C nuclear magnetic resonance (NMR) and electron ionization mass spectra (EI MS) data were developed for 108 compounds whose relative binding affinities (RBA) to the estrogen receptor are known. The (13)C NMR and EI MS data were used as spectrometric digital fingerprints to reflect the electronic and structural characteristics of the compounds. Both SDAR models segregated the 108 compounds into 20 strong, 15 medium, and 73 weak relative binding classifications. The first SDAR model, based on (13)C NMR data alone, gave a leave-one-out (LOO) cross-validation of 75.0%. The second SDAR model, based on a composite of (13)C NMR and EI MS data, gave a LOO cross-validation of 82.4%. Many of the misidentifications from the cross-validations were between medium and weak classifications, where there were fewer specific spectrometric characteristics to identify the relationship of spectra to estrogen receptor binding. Real and predicted (13)C NMR chemical shifts were used to test the predictive behavior of both SDAR models. The ease of use and speed of SDAR modeling may facilitate their use with other toxicological endpoints.

Producing 13C NMR, infrared absorption, and electron ionization mass spectrometric data models of the monodechlorination of chlorobenzenes, chlorophenols, and chloroanilines

We have developed four spectroscopic data-activity relationship (SDAR) models of monodechlorination of 32 chlorinated benzene compounds in anaerobic estuarine sediment. The SDAR models were based on combinations of 13C nuclear magnetic resonance (NMR), infrared absorption (IR), and electron ionization mass spectrometric (EI MS) data. The SDAR models segregated the 32 compounds into 17 readily monodechlorinated compounds and 15 not readily monodechlorinated compounds. The SDAR model based on 13C NMR, IR, and EI MS data gave a leave-one-out cross-validation of 93.8%. The SDAR model based on a composite of 13C NMR and IR data gave a leave-one-out cross-validation of 90.6%. The SDAR model based on a composite of IR and EI MS data gave a leave-one-out cross-validation of 84.4%. The SDAR model based on a composite of 13C NMR and EI MS data gave a leave-one-out cross-validation of 84.4%. These reliable SDAR models provide a rapid and simple way to predict whether a chlorinated benzene compound will readily go through monodechlorination. The FDA has filed a patent application on methods of using any combination of spectral data (NMR, MS, UV-vis, IR, and fluorescence, phosphorescence) to model a chemical, physical, or biological endpoint.

Potential clinical use of butyric acid derivatives to induce antigen-specific T cell inactivation

Compounds with the capacity to induce antigen-specific unresponsiveness in CD4(+) T cells can in some clinical situations be more beneficial than general immune suppressants. Newly synthesized ester, ester/amide, and amide derivatives of butyrate with the capacity to induce antigen-specific T cell unresponsiveness in vivo and in vitro were tested here. The ester and ester/amide derivatives of butyrate were shown to block proliferation by interleukin-2-stimulated murine Th1 cells in vitro. A 3-day treatment with these same two derivatives also suppressed a primary antibody response to a thymus-dependent antigen in mice. In addition, even a single injection of the ester derivative of n-butyrate 2-(4-morpholinyl)ethyl butyrate hydrochloride (MEB) on day 2 or 3 after immunization suppressed the generation of memory T cells capable of proliferating to antigen or of promoting a secondary antigen-specific antibody response. MEB also induced antigen-specific unresponsiveness in antigen-activated, but not resting or interleukin-2-activated, T cells in vitro. DNA analysis showed that regardless of when MEB was added to the cultures, it induced the eventual G(1) sequestration of essentially all activated Th1 cells. Because G(1) blockade is associated with Th1 cell anergy, this finding suggests that MEB has the potential to induce anergy in already-activated CD4(+) T cells. Taken together, the results presented here establish MEB as a novel means of inducing anergy in CD4(+) T cells both in vitro and in vivo and underscore the likelihood that MEB and/or other butyrate derivatives can be used as immunotherapeutic reagents.