Metabolism of Ro 21-5998 (mefloquine) in the rat (author's transl)

After administration of 15 mg/kg 14C-Ro 21-5998/001 i.p. to rats, the metabolite patterns in feces, urine, bile and blood were compared. Metabolites from feces were identified by GC/MS, in all other cases by TLC. The main component in the feces consists of mefloquine (Ro 21-5998). In addition the acid Ro 21-5104, a derivative of mefloquine with a hydroxy group in the piperidine moiety (M 12), the alcohol Ro 14-0518 and a metabolite (M 4a), which is supposed to be a lactam, were shown to be present. The acid Ro 21-5104 is the main metabolite in the urine. The bile contains the parent compound Ro 21-5998, the acid Ro 21-5104 and the alcohol Ro 14-0518, partially as conjugates. The structurally investigated components account for about 40% of the administered dose. The blood contains the parent compound Ro 21-5998 and the acid Ro 21-5104 as main components. In comparing the various metabolite patterns, it can be summarized that that in urine is slightly different from those in bile (after hydrolysis of the conjugates), feces and blood which show more similarities between each other.     

Biotransformation of 2-chloroaniline in the Fischer 344 rat: identification of urinary metabolites

1. The biotransformation of a single i.p. dose of [14C]2-chloroaniline (1.0 mmol/kg, approximately 60 microCi/rat) was investigated in the urine and faeces of the male Fischer 344 rat. 2. During 24 h, 53.1% of the administered radioactivity was eliminated into the urine, while < 1% of the radioactivity appeared in the faeces. 3. The major biotransformation pathways were para-hydroxylation and sulphate conjugation. 4-Amino-3-chlorophenyl sulphate was the major urinary metabolite comprising 31.6% of total urinary radioactivity. The para-hydroxylated metabolite, 4-amino-3-chlorophenol (10.8%), and its O-glucuronide conjugate (3.7%) were also urinary metabolites. The formation of direct conjugates of 2-chloroaniline, the N-sulphate and N-glucuronide, was significant with as much as 18.6 and 8.6%, respectively, of these metabolites excreted in the urine. The parent compound, 2-chloroaniline, accounted for 16.9% of urinary radioactivity. 4. N-Acetylated products were minor metabolites present in urine as 2-chloro-4-hydroxyacetanilide and its sulphate or glucuronide conjugate. Neither 2-chloroacetanilide nor its oxidation products, 2-chloroglycolanilide and 2-chlorooxanilic acid, were urinary metabolites.     

Gas chromatography-electron ionization and chemical ionization mass spectrometric analysis of urinary phenmetrazine after derivatization with 4-carbethoxyhexafluorobutyryl chloride--a new derivative

Phenmetrazine is a central nervous system stimulant currently used as an anorectic agent. The drug is abused and is reported to cause death from overdose. We describe a new derivatization method for phenmetrazine using 4-carbethoxyhexafluorobutyryl chloride. Quantitation of urinary phenmetrazine can be easily achieved by using N-ethyl amphetamine as an internal standard. The electron ionization mass spectrum of 4-carbethoxyhexafluorobutyryl derivative of phenmetrazine showed a molecular ion at m/z 427 and a base peak at m/z 70. In the methane chemical ionization mass spectrum, the base peak was observed at m/z 428 (protonated molecular ion). In the electron ionization mass spectrum of 4-carbethoxyhexafluorobutyryl derivative of the internal standard, N-ethyl amphetamine we did not observe a molecular ion. However, in the chemical ionization mass spectrum, the protonated molecular ion at m/z 414 was the base peak. The retention time of derivatized phenmetrazine (8.4 min) was substantially longer than the retention time of the underivatized molecule. Moreover, underivatized phenmetrazine showed poor peak shape (substantial tailing) while derivatized phenmetrazine had excellent chromatographic properties. The within-run and between-run precisions of the assay were 2.6% and 3.1% respectively at a urinary phenmetrazine concentration of 10 micrograms/mL. The assay was linear for urinary phenmetrazine concentration of 1 to 100 micrograms/mL with a detection limit of 0.2 microgram/mL.     

Determination of seven prostanoids in 1 ml of urine by gas chromatography-negative ion chemical ionization triple stage quadrupole mass spectrometry

In an isotope dilution assay, prostaglandin (PG) E2, 6-keto-PGF1 alpha, thromboxane (Tx) B2 and their metabolites PGE-M (11 alpha-hydroxy-9,15-dioxo-2,3,4,5,20-pentanor-19-carboxyprostano ic acid), 2,3-dinor-6-keto-PGF1 alpha, 2,3-dinor-TxB2 and 11-dehydro-TxB2 were determined in urine by gas chromatography-triple stage quadrupole mass spectrometry (GC-MS-MS). After addition of deuterated internal standards, the prostaglandins were derivatized to their methoximes and extracted with ethyl acetate-hexane. The sample was further derivatized to the pentafluorobenzylesters and purified by thin-layer chromatography (TLC). Three zones were scraped from the TLC plate. The prostanoid derivatives were converted to their trimethylsilyl ethers and the products were quantified by GC-MS-MS. In each run, two or three prostanoids were determined.     

Biotransformation of irbesartan in man

The metabolism of irbesartan, a highly selective and potent nonpeptide angiotensin II receptor antagonist, has been investigated in humans. An aliquot of pooled urine from healthy subjects given a 50-mg oral dose of [14C]irbesartan was added as a tracer to urine from healthy subjects that received multiple, 900-mg nonradiolabeled doses of irbesartan. Urinary metabolites were isolated, and structures were elucidated by mass spectroscopy, proton NMR, and high-performance liquid chromatography (HPLC) retention times. Irbesartan and the following eight metabolites were identified in human urine: (1) a tetrazole N2-beta-glucuronide conjugate of irbesartan, (2) a monohydroxylated metabolite resulting from omega-1 oxidation of the butyl side chain, (3, 4) two different monohydroxylated metabolites resulting from oxidation of the spirocyclopentane ring, (5) a diol resulting from omega-1 oxidation of the butyl side chain and oxidation of the spirocyclopentane ring, (6) a keto metabolite resulting from further oxidation of the omega-1 monohydroxy metabolite, (7) a keto-alcohol resulting from further oxidation of the omega-1 hydroxyl of the diol, and (8) a carboxylic acid metabolite resulting from oxidation of the terminal methyl group of the butyl side chain. Biotransformation profiles of pooled urine, feces, and plasma samples from healthy male volunteers given doses of [14C]irbesartan were determined by HPLC. The predominant drug-related component in plasma was irbesartan (76-88% of the plasma radioactivity). None of the metabolites exceeded 9% of the plasma radioactivity. Radioactivity in urine accounted for about 20% of the radiolabeled dose. In urine, irbesartan and its glucuronide each accounted for about 5 to 10% of the urinary radioactivity. The predominant metabolite in urine was the omega-1 hydroxylated metabolite, which constituted about 25% of the urinary radioactivity. In feces, irbesartan was the predominant drug-related component (about 30% of the radioactivity), and the primary metabolites were monohydroxylated metabolites and the carboxylic acid metabolite. Irbesartan and these identified metabolites constituted 90% of the recovered urinary and fecal radioactivity from human subjects given oral doses of [14C]irbesartan.     

Rat fetal ventral mesencephalon grown as solid tissue cultures: influence of culture time and BDNF treatment on dopamine neuron survival and function

The method of analysis described permits the determination of 2,4-dinitrobenzoic acid down to the lower microg l(-1) range in the urine of persons exposed to dinitrotoluene. 2,4-Dinitrobenzoic acid is the main metabolite of 2,4-dinitrotoluene and technical dinitrotoluene. After acidic hydrolysis, which served to release the conjugated part of the 2,4-dinitrobenzoic acid, the analyte was selectively separated from the urine matrix via various extraction steps and then derivatised to the methyl ester. Quantitative analysis was carried out using capillary gas chromatography and mass selective detection. 3,5-Dinitrobenzoic acid was used as an internal standard. The detection limit was 1 microg l(-1) urine. The relative standard deviations of within-series imprecision were between 5 and 6%. The relative recoveries were between 91 and 110% depending on the concentration. The analytical method developed as part of this study was used to investigate a collective consisting of 82 urine samples from persons working in the area of explosives disposal. The concentrations of 2,4-dinitrobenzoic acid determined ranged from the detection limit to 95 microg l(-1) urine. The method allowed the quantification of low-level internal exposure to dinitrotoluene.     

Determination of rifampicin and its main metabolite in plasma and urine in presence of pyrazinamide and isoniazid by HPLC method

A reversed phase HPLC method is described for the simultaneous estimation of rifampicin and its major metabolite desacetyl rifampicin, in the presence of isoniazid and pyrazinamide, in human plasma and urine. The assay involves simple liquid extraction of drug, metabolite and internal standard (rifapentine) from biological specimens and their subsequent separation on a C18 reversed phase column and single wavelength UV detection. In plasma as well as in urine samples, all the three compounds of interest eluted within 17 min. Using methanol-sodium phosphate buffer (pH 5.2; 0.01 M) (65:35, v/v) as mobile phase under isocratic conditions, it was established that isoniazid, pyrazinamide and ascorbic acid (added to prevent oxidative degradation of analytes) did not interfere with the analyte peaks. Recoveries (extraction efficiency) for drug were greater than 90% in both plasma and urine, whereas for metabolite the values were found to be 79 and 86% in plasma and urine, respectively. The plasma and urine methods were precise (total coefficient of variation ranged from 5 to 23%) and accurate (-7 to 5% of the nominal values) for both the analytes. Individual variance components, their estimates and their contribution to the total variance were also determined. Using the same method, unknown samples supplied by WHO were assayed and good correlations were obtained between the found and intended values. The method developed proved to be suitable for simultaneous estimation of rifampicin and desacetyl rifampicin in plasma and urine samples.     

Spectrofluorometric determination of substituted tetrahydrocarbazoles by a methylene blue sensitized photolytic reaction

A spectrofluorometric method was developed for the determination of 6-chloro-9-[2-(2-methyl-5-pyridyl)ethyl]-1,2,3,4-tetrahydrocarbazole-2-methanol hydrochloride and its carboxylic acid analog in blood and urine. It involves extraction of both compounds at neutral pH, either from blood into ethyl acetate (the residue of which is dissolved in either) or from urine directly into ether. Both the alcohol and the acid are separated from each other by selective extraction into acid or base, respectively, and then reextracted into either from the respective aqueous medium by appropriate pH adjustment. The residues of the ether extracts containing the compounds are dissolved separately in 0.25 N NH4OH. Methylene blue is added to all samples, which are then exposed to UV energy for 15 min to produce the fluorophores. The fluorescence of the solutions is read at 370 nm, with excitation at 340 nm. The linear range of quantitation of both compounds is 0.02-10 mug/each/ml of final solution. The method was applied to the determination of blood levels and urinary excretion of the alcohol and its acid metabolite in a dog.     

Formation of a metabolite of dibromosulfophthalein (DBSP) in man

In bile specimens from postoperative patients with biliary drainage following cholecystectomy, in addition to unchanged dibromosulfophthalein (DBSP), a single polar metabolite of DBSP was found after i.v. injection of 5 mg/kg of the diagnostic dye. This metabolite, which has not previously been detected, was resistant to beta-glucuronidase and arylsulfatase and was remarkably stable in strongly acid and alkaline solutions. It exhibited the same spectrum and colour change interval as unchanged DBSP. Further studies of its identity revealed that it gave a ninhydrin-positive reaction and that its Rf-value on TLC could be restored by Raney-nickel reduction. Amino-acid analysis after reduction and acid hydrolysis showed an increase in glutamic acid and alanine that can be considered as splitting products of conjugated glutathione following these procedures. Estimation of the quantity of this possible glutathione conjugate indicates that it is formed less rapidly than the glutathione derivative of the tetrabromoanalogue BSP, and that it represents up to 25% of the total dye excreted in bile. The observed metabolism of DBSP in man may complicate its use in the study of hepatic transport function, and negates the previous assumption that, as in certain other animal species, the dye is excreted unchanged.     

A study of metabolites isolated from the urine samples of cats and dogs administered orbifloxacin

Urine samples of cats and dogs collected for 24 hr after a subcutaneous injection of orbifloxacin (OBFX) were analyzed. The metabolites were examined using HPLC. In the dog urine, 87% of total was the parent compound and 13% glucuronide compound of OBFX and 96% was parent and 4% metabolite in the cat urine. The metabolite of cat urine was identified as N-hydroxy OBFX, determined by comparison of the extraction of urine with chloroform with the standard compound of N-hydroxy OBFX, using LC/APCIMS. N-hydroxy OBFX had a weaker antibacterial activity against fluoroquinolone sensitive bacteria than the parent compound.     

Biotransformation of trithiozine. III - Isolation and identification of further metabolites in rat urine

The metabolism of a new antisecretory and antiulcer drug, trithiozine (I.S.F. 2001, T), was studied in 4 hr rat urine samples after i.p. administration. After extraction at pH 7 with chloroform, the urine was either incubated with beta-glucuronidase or acidified to pH 2 and subsequently extracted with chloroform. The organic layers were evaporated to dryness and the residues used for TLC analysis. The neutral extracts revealed five spots, not present in control rat urine, corresponding to the unchanged drug T and to four metabolites. Two of the metabolites had been previously identified as the 4-(3,4,5-trimethoxybenzoyl)tetrahydro-1,4-oxazine (TBO) and the 4-(3,4,5-trimethoxythiobenzoyl)tetrahydro-1,4-oxazine-S-oxide (TO). Three other metabolites were found in the extracts after beta-glucuronidase incubation. TLC, U.V. and M.S. data were consistent with the structure 4-(3,5-dimethoxy-4-hydroxythiobenzoyl)tetrahydro-1,4-oxazine (HT), the corresponding S-oxide (HO) and the 4-(3,5-dimethoxy-4-hydroxybenzoyl)tetrahydro-1,4-oxazine (HBO). The acidic extracts revealed two spots structurally identified as the 3,4,5-trimethoxybenzoic acid (TBA) and the previous HBO. On the basis of present knowledge, a possible metabolic pathway of T is reported, consisting in a rapid metabolic oxidation on the sulfur atom and a slower demethylation on the para methoxy group. The presence of TBA is indicative of subsequent enzymatic hydrolysis of TBO. The intense and long-lasting inhibitory effect of T on gastric secretion is tentatively correlated with the pharmacological activities of some of its metabolites.     

Comparative metabolism of bis(2-methoxyethyl)ether in isolated rat hepatocytes and in the intact rat: effects of ethanol on in vitro metabolism

The metabolism of the reproductive and developmental toxicant bis(2-methoxyethyl)ether (diglyme) was studied in isolated rat hepatocytes and in the intact rat. Male Sprague-Dawley rats (190-220 g) were used in both studies. Hepatocytes, isolated by a two-step in situ collagenase perfusion of the liver, were cultured as monolayers and incubated with [14C]diglyme at 1, 10, 30, and 50 microM for up to 48 h. For the in vivo study, rats were given single oral doses of [14C]diglyme at 5.1 mmol/kg body wt, and urine was collected for up to 96 h. Radioactive compounds in the culture medium or in the urine were separated by high performance liquid chromatography and quantified with an in-line radioactivity monitor. Metabolites were identified by comparison of their chromatographic retention times and their mass spectra with those of authentic compounds. The principal metabolite from hepatocytes and in the urine was (2-methoxyethoxy)acetic acid (MEAA). This metabolite accounted for approximately 36% of the radioactivity in the 48-h culture medium and about 67% of the administered dose in the 48-h urine. Other prominent metabolites common to both systems included 2-(2-methoxyethoxy)ethanol, methoxyacetic acid (MAA), 2-methoxyethanol, and diglycolic acid. The diglyme metabolite profiles from urine and from hepatocytes were qualitatively similar, demonstrating that, in the rat, hepatocytes serve as a good model system for predicting the urinary metabolites of diglyme. Moreover, MEAA was shown to be the metabolite best suited for use as a short-term biological marker of exposure to diglyme.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mass spectrometric characterization and HPLC determination of the main urinary metabolites of nimesulide in man

A study was undertaken for the characterization and quantitative determination of the main urinary metabolites of the non-steroidal anti-inflammatory drug (NSAID) nimesulide (4-nitro-2-phenoxy-methanesulfonanilide) in man following single oral administration (200 mg). Urines were collected from six healthy volunteers at 12, 24, 48, 72 and 96 h post-administration and submitted to liquid liquid extraction before (free metabolites) and after enzymatic hydrolysis (conjugated metabolites). The structure of the metabolites, isolated by TLC separation, was elucidated by mass spectrometry (electron impact ionization) and confirmed by synthesis. Five metabolites were identified: they arise from hydroxylation to the phenoxy nucleus (M1 = hydroxynimesulide); reduction of the nitro group to an amino derivative (M2); concomitant hydroxylation and reduction (M3); N-acetylation of the M2 (M4) and of the M3 (M5) metabolites. Quantitation was by reverse phase high performance liquid chromatography (Supelcosil LC-18 DB column; mobile phase: sodium phosphate buffer (pH 3.0, 50 mM)-acetonitrile (gradient elution); flow rate: 1 ml min(-1); UV detection, 230 nm), procedure which allows in a single chromatographic run the simultaneous determination of the unchanged drug and of its metabolites. The urinary excretion of the drug and metabolites (free + conjugated) in the overall 96 h-interval accounts for approximately 40% of the administered dose: 17.55 +/- 3.6% M1; 0.72 +/- 0.43% M2; 2.45 +/- 1.22% M3; 19.07 +/- 4.3% M5. The bulk of the metabolites was in conjugated form. Percentages excretion of the unchanged drug and of M4 metabolite were below 0.5%. The described method is suited to specifically and quantitatively measure nimesulide and metabolites in human urine with acceptable precision and accuracy.     

A new sulfur amino acid, named hawkinsin, identified in a baby with transient tyrosinemia and her mother

An unknown compound present in the urine of a girl with prolonged transient tyrosinemia and her mother was isolated and identified as (2-L-cystein-S-yl-1,4-dihydroxycyclohex-5-en-1-yl)-acetic acid (IVa). The new amino acid was named hawkinsin (Haw) and characterized by gas chromatography-mass spectrometry (GC-MS) of its penta-trimethylsilyl (TMS) derivative and of its desulfuration components. Haw was compared with the synthetic reference compound using GC-MS, IR, TLC, PC, ion-exchange chromatogrpahy and high-voltage electrophoresis. IVa and (2,6-bis-L-cystein-S-yl-1,4-dihydroxycyclohexyl-1)-acetic acid were synthesized from 4-quinolacetic acid, the latter was prepared in two different ways. It is postulated that Haw originates from an intermediate in the 4-hydroxy-phenylpuruvate hydroxylase reaction (EC 1.14.2.2), and that mother and child are heterozygous for an inborn error of metabolism characterized by a defect in this hydroxylase system, which is unable to rearrange the intermediate to homogentisic acid.     

Intraperitoneal photodynamic therapy: comparison of red and green light distribution and toxicity

Ceftiofur sodium is the salt of (6R,7R)-7-{[(2-amino-4-thiazolyl)-Z-(methoxyimino)acetyl]amino}-3-{[(2-+ ++furanylcarbonyl)thio]methyl}-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2- ene-2-carboxylic acid. This compound is very susceptible to acid, alkaline-, and enzyme-catalyzed hydrolysis, producing a number of unstable degradation products. In this report, we describe the preparation and identification of the hydrolysis products that are formed under controlled alkaline conditions. The primary hydrolysis product was desfuroyl ceftiofur, which is the most abundant metabolite in bovine blood. Desfuroyl ceftiofur was carefully oxidized with H2O2 to prepare the disulfide dimer, a urinary metabolite of ceftiofur sodium in the rat and cattle. Under acidic conditions, desfuroyl ceftiofur was converted to the corresponding thiolactone. The preparation of desacetyl cefotaxime, which is the oxygen analog of desfuroyl ceftiofur, is also described. Furoic acid was readily formed by hydrolytic cleavage of the thioester bond. Thiofuroic acid, formed by the less common cleavage on the alkyl side of the thioester bond, was also isolated.     

Identification and measurement of endogenous beta-oxidation metabolites of 8-epi-Prostaglandin F2alpha

F2-isoprostanes are prostaglandin-like compounds derived from nonenzymatic free radical-catalyzed peroxidation of arachidonic acid. 8-epi-Prostaglandin (PG) F2alpha, a major component of the F2-isoprostane family, can be conveniently measured in urine to assess noninvasively lipid peroxidation in vivo. Measurement of major metabolites of endogenous 8-epi-PGF2alpha, in addition to the parent compound, may be useful to better define its formation in vivo. 2,3-Dinor-5,6-dihydro-8-epi-PGF2alpha is the only identified metabolite of 8-epi-PGF2alpha in man, but its endogenous levels are unknown. In addition to this metabolite, we have identified another major endogenous metabolite, 2,3-dinor-8-epi-PGF2alpha, in human and rat urine. The identity of these compounds, present at the pg/ml level in urine, was proven by a number of complementary approaches, based on: (a) immunoaffinity chromatography for selective extraction; (b) gas chromatography-mass spectrometry for structural analysis; (c) in vitro metabolism in isolated rat hepatocytes; and (d) chemical synthesis of the enantiomer of 2,3-dinor-5, 6-dihydro-8-epi-PGF2alpha as a reference standard. In humans, the urinary excretion rate of both dinor metabolites is comparable with that of 8-epi-PGF2alpha. Both metabolites increase in parallel with the parent compound in cigarette smokers, and they are not reduced during cyclooxygenase inhibition. Another beta-oxidation product, 2, 3,4,5-tetranor-8-epi-PGF2alpha, was identified as a major product of rat hepatocyte metabolism. In conclusion, at least two major beta-oxidation products of 8-epi-PGF2alpha are present in urine, which may be considered as additional analytical targets to evaluate 8-epi-PGF2alpha formation and degradation in vivo.     

The biodegradation of the surfactant undecyl sulphate

1. The metabolism of the odd-numbered carbon chain surfactant, potassium undecyl [35S]sulphate in the rat was investigated. 2. The major route for elimination of radioactivity was the urine, regardless of the route of administration. 3. The surfactant was extensively degraded in vivo to yield propionic acid 3-[35S]sulphate, the major radioactive component in urine. A second urinary metabolite was identified tentatively as pentanoic acid 5-[35S]sulphate. 4. Whole-body autoradiography revealed the liver as the major site of metabolism. 5. The nature of the metabolic products of undecyl sulphate suggest that it is bio-degraded by initial omega-oxidation followed by beta-oxidation.     

镍铁渣在混凝土综合利用中的环境风险研究

从浸出机制和迁移扩散角度出发,研究了镍铁渣的产酸潜势、浸出毒性和其混凝土产品的浸出毒性。结果表明,镍铁渣产酸潜势为不产酸,本身不是一个酸性排放源;腐蚀性、浸出毒性小于国家标准限值。镍铁渣混凝土产品在酸性和碱性环境下,只有砷少量浸出,但未超过《地下水质量标准》。因此,镍铁渣可以直接入场作为混凝土掺和料进行综合应用,环境风险较小。     

In vivo adulteration: excess fluid ingestion causes false-negative marijuana and cocaine urine test results

Drug users can be highly motivated to obtain negative results on urine drug tests and may attempt to subvert the process by in vivo adulteration. The use of herbal products for "flushing" and "detoxification" is frequently advertised as an effective means of passing drug tests. Accordingly, a study was designed to determine the effects of ingestion of two herbal products, Naturally Klean Herbal Tea and Golden Seal root, and a diuretic medication, hydrochlorothiazide. The herbal tea was prepared in 1 gal of water as specified by the manufacturer. All other products were consumed with 1 gal of water. Two control conditions in which the subject consumed only water (1 gal; 12 oz) were included. The 1-gal liquid treatments were divided into 4-qt aliquots, and 1-qt was consumed each hour for 4 h. All treatments were begun approximately 22 h after smoking of a marijuana cigarette (3.58% THC) and 22 h after intranasal administration of cocaine hydrochloride. Following all treatments with excess fluid, creatinine and specific gravity dropped in 1.5-2.0 h to levels indicative of diluted specimens (<20 mg/dL creatinine, <1.003 specific gravity). Marijuana and cocaine metabolite concentrations by immunoassay (EMIT and TDx) also dropped rapidly, and the results frequently switched from positive to negative. By the time subjects had consumed 2 qt of any fluid, they were generally producing false-negative results. For example, ingestion of excess water produced dilute specimens (<20 mg/dL creatinine; <1.003 specific gravity) in an average time plus or minus the standard error of the mean of 1.47 +/- 0.17 h (N = 5) and 1.45 +/- 0.2 h (N = 5) following smoked marijuana and intranasal cocaine, respectively. In comparison, ingestion of Klean Tea produced dilute specimens in 1.36 +/- 0.07 h (N = 4) and 1.39 +/- 0.11 h (N = 4) following marijuana and cocaine administration. Recovery of urine test measures to pre-treatment levels occurred over a period of 8-10 h. Average detection times for marijuana metabolite appeared to be slightly shorter following ingestion of 1 gal of fluids compared with ingestion of 12 oz of water as a result of the time of testing being near the end of the cannabinoid metabolite excretion phase. Consequently, negative cannabinoid results induced by fluid ingestion rarely returned to positive after excess water was eliminated. In contrast, negative cocaine results reverted to positive quickly after the dilution effects disappeared. It was concluded that excess water ingestion can produce false-negative test results, but the claims of herbal products to be an aid in passing a urine test appear to be unfounded.     

Ferulic acid dehydrodimers from wheat bran: isolation, purification and antioxidant properties of 8-O-4-diferulic acid

Wheat bran contains several ester-linked dehydrodimers of ferulic acid, which were detected and quantified after sequential alkaline hydrolysis. The major dimers released were: trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxy-phenyl)-7-methoxy-2, 3- dihydrobenzofuran-3-carboxylic acid (5-8-BendiFA), (Z)-beta-[4-[(E)-2-carboxyvinyl]-2-methoxyphenoxy]-4-hydroxy-3-methox ycinnamic acid (8-O-4-diFA) and (E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid (5-5-diFA). trans-7-hydroxy-1-(4-hydroxy-3methoxyphenyl)-6-methoxy-1,2-dihydro - naphthalene-2,3-dicarboxylic acid (8-8-diFA cyclic form) and 4,4'-dihydroxy-3,3'-dimethoxy-beta,beta'-bicinnamic acid (8-8-diFA non cyclic form) were not detected. One of the most abundant dimers, 8-O-4-diFA, was purified from de-starched wheat bran after alkaline hydrolysis and preparative HPLC. The resultant product was identical to the chemically synthesised 8-O-4-dimer by TLC and HPLC as confirmed by 1H-NMR and mass spectrometry. The absorption maxima and absorption coefficients for the synthetic compound in ethanol were: lambda max: 323 nm, lambda min: 258 nm, epsilon lambda max (M-1 cm-1): 24,800 +/- 2100 and epsilon 280 (M-1 cm-1): 19,700 +/- 1100. The antioxidant properties of 8-O-4-diFA were assessed using: (a) inhibition of ascorbate/iron-induced peroxidation of phosphatidylcholine liposomes and; (b) scavenging of the radical cation of 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulphonate) (ABTS) relative to the water-soluble vitamin E analogue, Trolox C. The 8-O-4-diFA was a better antioxidant than ferulic acid in both lipid and aqueous phases. This is the first report of the antioxidant activity of a natural diferulate obtained from a plant.