Optimization of a nano-enzymatic reactor for on-line tryptic digestion of polypeptide conjugates by capillary electrophoresis.

This work aims at studying the optimization of an on-line capillary electrophoresis (CE)-based tryptic digestion methodology for the analysis of therapeutic polypeptides (PP). With this methodology, a mixture of surrogate peptide fragments and amino acid were produced on-line by trypsin cleavage (enzymatic digestion) and subsequently analyzed using the same capillary. The resulting automation of all steps such as injection, mixing, incubation, separation and detection minimizes the possible errors and saves experimental time. In this paper, we first study the differents parameters influencing PP cleavage inside the capillary (plug length, reactant concentration, incubation time, diffusion and electrophoretic plugs mixing). In a second part, the optimization of the electrophoretic separation conditions of generated hydrolysis products (nature, pH and ionic strength (I) of the background electrolyte (BGE)) is described. Using the optimized conditions, excellent repeatability was obtained in terms of separation (migration times) and proteolysis (number of products from enzymatic hydrolysis and corresponding amounts) demonstrating the robustness of the proposed methodology.

Analytical characterization of bioactive N-benzyl-substituted phenethylamines and 5-methoxytryptamines.

RATIONALE: Substances based on the N-(2-methoxybenzyl)phenethylamine template ('NBOMe' derivatives) play an important role in medicinal research but some of these derivatives have also appeared as 'research chemicals' for recreational use which has attracted attention worldwide. A major challenge associated with newly emerging substances includes the lack of analytical data and the ability to correctly identify positional isomers. METHODS: Six N-benzylphenethylamines based on the 2,5-dimethoxy-4-iodophenethylamine structure ('25I') and twelve substituted N-benzyl-5-methoxytryptamines ('5MT') have been prepared and extensively characterized. Techniques used for characterization were gas chromatography/ion trap mass spectrometry in electron and chemical ionization mode, liquid chromatography/diode array detection (DAD), infrared spectroscopy, electrospray high mass accuracy quadrupole time-of-flight tandem mass spectrometry, and triple quadrupole tandem mass spectrometry. RESULTS: The characterization of 18 'NBOMe' compounds provided a comprehensive collection of chromatographic and spectral data. Four groups of three positional isomers, i.e. 25I-NB2OMe, 25I-NB3OMe, 25I-NB4OMe, 25I-NB2B, 25I-NB3B, 25I-NB4B and their 5-methoxytryptamine counterparts, were included and assessed for ability to obtain differentiation. Six meta-substituted N-benzyl derivatives of 5-methoxytryptamine (CF3, F, CH3, Cl, I, SCH3) were also studied. CONCLUSIONS: The implementation of mass spectral techniques was helpful for the differentiation between isomers, for example, when considering the difference in a number of ion ratios. This was considered beneficial in cases where chromatographic separation was only partially achieved under liquid chromatography (LC) conditions. The use of LC/DAD analysis was also found to be valuable for this particular purpose, which confirmed the integrative value of complementary techniques used in areas related to forensic toxicology.

Application of hair analysis to document illegal 5-methoxy-N,N-dissopropyltrptamine (5-MeO-DiPT) use.

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DiPT) is a designer hallucinogen that is a synthetic tryptamine derivative. It is highly abused and is involved in criminal activities because of its psychotropic properties. Herein, we presented an UHPLC-MS/MS method allowing for the qualitative and quantitative determination of 5-MeO-DiPT in human hair. The hair was first decontaminated and then cut into pieces. Thirty milligrams of hair samples was pulverized below 4°C in the presence of 0.5mL deionized water containing 0.1% formic acid. After centrifuging twice, 5µL of supernatant was injected into the LC-MS/MS system. A T3 column (100mm×2.1mm, 1.8µm) was used, and mobile phases consisted of 20mmol/L ammonium acetate, 5% acetonitrile and 0.1% formic acid in water (solvent A) and acetonitrile (solvent B). The gradient elution was used at a flow rate of 0.3mL/min. The resulting calibration curve for 5-MeO-DiPT was y=281.50213x+0.00231 (R2=0.992), the limit of detection (LOD) was 0.05pg/mg, and the lower limit of quantification (LLOQ) was 0.1pg/mg. The accuracy was between 92.1% and 105.6%, and the intra- and interday precision, recovery and matrix effect were acceptable. The validated method was successfully used in 106 real cases, and the concentration of 5-MeO-DiPT in hair samples of these suspected users was 0.2-7532.5pg/mg. These cases present data to document illegal 5-MeO-DiPT use.

Proposal of 5-methoxy-N-methyl-N-isopropyltryptamine consumption biomarkers through identification of in vivo metabolites from mice.

New psychoactive substances (NPS) are a new breed of synthetically produced substances designed to mimic the effects of traditional illegal drugs. Synthetic cannabinoids and synthetic cathinones are the two most common groups, which try to mimic the effects of the natural compounds 9Δ-tetrahydrocannabinol and cathinone, respectively. Similarly, synthetic tryptamines are designer compounds which are based on the compounds psilocin, N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine found in some mushrooms. One of the most important tryptamine compounds found in seizures is 5-methoxy-N,N-diisopropyltryptamine, which has been placed as controlled substance in USA and some European countries. The control of this compound has promoted the rising of another tryptamine, the 5-methoxy-N-methyl-N-isopropyltryptamine, which at the time of writing this article has not been banned yet. So, it is undeniable that this new substance should be monitored. 5-methoxy-N-methyl-N-isopropyltryptamine has been reported by the Spanish Early Warning System and detected in our laboratory in two pill samples purchased in a local smart shop. This has promoted the need of stablishing consumption markers for this compound in consumers' urine. In the present work, the metabolism and pharmacokinetic of 5-methoxy-N-methyl-N-isopropyltryptamine has been studied by an in vivo approach, using adult male mice of the inbred strain C57BLJ/6. The use of ultra-high performance liquid chromatography coupled to high resolution mass spectrometry allowed the identification of four metabolites. After the pharmacokinetic study in serum and urine, the O-demethylated metabolite and the non-metabolised parent compound are proposed as consumption markers in hydrolysed urine. Data reported in this work will help hospitals and forensic laboratories to monitor the consumption and potential intoxication cases related to this tryptamine.

Sensitive determination of alpha-methyltryptamine (AMT) and 5-methoxy-N,N-diisopropyltryptamine (5MeO-DIPT) in whole blood and urine using gas chromatography-mass spectrometry.

We devised a sensitive and simple method to determine alpha-methyltryptamine (AMT) and 5-methoxy-N,N-diisopropyltryptamine (5MeO-DIPT) in whole blood and urine, using gas chromatography-mass spectrometry (GC-MS). AMT and 5MeO-DIPT were extracted using an Extrelut column with an internal standard, bupivacaine, followed by derivatization with acetic anhydride. The derivatized extract was used for GC-MS analysis of EI-SIM mode. The calibration curves of AMT and 5MeO-DIPT were linear in the concentration range from 10 to 750 ng/ml in both blood and urine samples. The method detection limit (MDL) of AMT and 5MeO-DIPT were 1 ng/ml each in whole blood and 5 ng/ml each in urine. This method should be most useful to accurately determine the presence of these drugs in blood and urine in clinical and forensic cases.

Rapid, accurate and precise quantitative drug analysis: comparing liquid chromatography tandem mass spectrometry and chip-based nanoelectrospray ionisation mass spectrometry.

We have developed a liquid chromatography tandem mass spectrometry (LC-MS/MS) system capable of achieving better than 2% accuracy, routinely over a wide concentration range of 1800 ng mL-1. We demonstrate that the necessary high precision, high accuracy and rapid analysis can be achieved using LC-MS/MS technology. Automated nanoelectrospray ionisation tandem mass spectrometry (nanoESI-MS/MS) technology can be employed to eliminate the chromatographic step completely. In this paper, nanoESI-MS/MS is evaluated and compared directly with LC-MS/MS for the quantitative analysis of two-test analytes, amitriptyline (ATT) and 5-methoxytryptamine (5-MTT), in aqueous/organic mixture. Calibration curves were found to be linear over a wide concentration range of 1800 ng mL-1 for both analytes using LC-MS/MS. Using nanoESI-MS/MS ATT gave a linear response while 5-MTT gave a non-linear response using nanoESI-MS/MS over the same concentration range as in LC-MS/MS. Accuracy and precision values of quality control samples (QCs) at four concentration levels were analysed in replicates of six at each level using 5-MTT and ATT as test analytes for both techniques. The LC-MS/MS system was capable of achieving accuracy levels of 99.50101.96% for ATT and 100.17100.40% for 5-MTT. Accuracy levels using nanoESI-MS/MS were not comparable to LC-MS/MS, they ranged from 90.09100.18% for ATT and 95.95113.55% for 5-MTT. The precision values obtained for nanoESI-MS/MS were in good agreement with those obtained by LC-MS/MS.

Melatonin deacetylase activity in the pineal gland and brain of the lizards Anolis carolinensis and Sceloporus jarrovi.

Melatonin modulates a variety of rhythmic processes in vertebrates, and is synthesized in both the retina and pineal gland. We have shown previously that retinal melatonin is deacetylated generating 5-methoxytryptamine, which is then deaminated by monoamine oxidase, producing 5-methoxyindoleacetic acid and 5-methoxytryptophol. This process occurs within the eyes of a variety of vertebrates including the iguanid lizard Anolis carolinensis. To determine whether melatonin deacetylase activity also occurs in the pineal organ or in other parts of the lizard brain, pineals and brains of Anolis carolinensis and Sceloporus jarrovi were cultured in the presence of [3H-methoxy]-melatonin. High-performance liquid chromatography of the resulting culture media and tissues revealed the generation of radiolabeled 5-methoxytryptamine and 5-methoxyindoleacetic acid. These two methoxyindoles were the only radiolabeled metabolites detectable, and together accounted for all melatonin lost. Both the loss of melatonin and the production of melatonin metabolites were inhibited by inclusion of 100 microM eserine, an inhibitor of the melatonin deacetylase. Pargyline, a monoamine oxidase inhibitor, reduced the production of 5-methoxyindoleacetic acid and increased the production of 5-methoxytryptamine relative to control incubations. Similar effects of eserine and pargyline were seen in eyecup, brain and pineal gland, but the specific activity of melatonin deacetylation in cultured pineal glands was much greater than in either brains or eyecups. These results indicate that pineal glands of both Anolis carolinensis and Sceloporus jarrovi can rapidly catabolize melatonin by a mechanism very similar to that in the eye, that the melatonin deacetylation pathway exists elsewhere in the iguanid brain, and also extend our previous observations of ocular melatonin deacetylation to an additional species.

MAO inhibition and the effects of centrally administered LSD, serotonin, and 5-methoxytryptamine on the conditioned avoidance response in rats.

Pretreatment with the MAO-inhibitors iproniazid, clorgyline, or deprenyl abolishes the effects of LSD on the conditioned avoidance response (CAR) in rats. The effects of serotonin (5-HT) and 5-methoxytryptamine (5-MT) are greatly potentiated by these substances. Brain levels of LSD are not affected by MAO inhibition whereas levels of 5-HT and 5-MT are significantly elevated. It is postulated that the decreased behavioral response to LSD is the result of 'MAO inhibitor-induced' changes whereas the increased response of 5-HT and 5-MT results from increased brain levels of these compounds.

A general screening and confirmation approach to the analysis of designer tryptamines and phenethylamines in blood and urine using GC-EI-MS and HPLC-electrospray-MS.

Recent additions of designer tryptamines and phenethylamines to the Drug Enforcement Administration's schedule of controlled substances necessitate analytical procedures for their detection and quantitation. As specific immunoassays are not currently available and cross-reactivities with existing assays are unknown, a screening method based on gas chromatography-mass spectrometry was developed. The method was capable of measuring the pentafluoropropionic derivatives of a-methyltryptamine (AMT), N,N-dimethyltryptamine (DMT), 4-bromo-2,5-dimethoxy-beta-phenethylamine (2CB), N,N-dipropyltryptamine (DPT), 2,5-dimethyl-4-N-propylthio-beta-phenethylamine (2C-T-7), and 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DiPT). Separation was optimized to allow tentative identification of metabolites, which display common electron impact ionization fragmentation patterns. The screening method gave limits of detection between 5 and 10 ng/mL and demonstrated linearity between 50 and 1000 ng/mL. The method was successfully applied to blood and urine samples in suspected AMT intoxications. Confirmation of 5-MeO-DiPT in one of the subjects' urine was achieved using liquid chromatography-mass spectrometry (LC-MS). Quantitation by selected ion monitoring (SIM) yielded a urinary concentration of 229 ng/mL. The method was linear from 25 to 1500 ng/mL with a correlation coefficient of 0.995. The limit of detection was 5 ng/mL in urine on the LC-MS. Two additional peaks were observed and presumed to be metabolic products reported previously as 5-methoxy-N-isopropyltryptamine (5-MeO-iPT) and 5-methoxy-N,N-diisopropyltryptamine-N'-oxide (5-MeO-DiPT-N-oxide).

Hydroxypropyl-beta-cyclodextrin enhanced fluorimetric method for the determination of melatonin and 5-methoxytryptamine.

The effects of native cyclodextrins (alpha, beta or gamma), hydroxypropyl-beta-cyclodextrin, beta-cyclodextrin solubilized in urea, soluble starch and glucose in water solution on the fluorescence behaviour of melatonin (N-acetyl-5-methoxytryptamine) (M) and 5-methoxytryptamine [5-methoxy-3-(2-aminoethyl)indole] (5M) were determined. In addition, the effect of methanol and propanol with and without beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin was assessed. From the fluorescence changes with pH, the values of the pKa for the ground (9.9 +/- 0.2) and the excited state (7.7 +/- 0.2) for 5M were determined. From the fluorescence changes with beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin, the association constants of M, 5MH [5-methoxy-3-(2-ammoniumethyl)indole] and 5M with the two hosts were determined. The values with beta-cyclodextrin were KAssoc5MH = (1.4 +/- 0.4) x 10(2) mol-1 dm3, KAssoc5M = (1.6 +/- 0.1) x 10(2) mol-1 dm3 and KAssocM = (1.1 +/- 0.2) x 10(2) mol-1 dm3, and with hydroxypropyl-beta-cyclodextrin KAssoc5MH = (1.1 +/- 0.3) x 10(2) mol-1 dm3, KAssoc5M = (2.5 +/- 0.1) x 10(2) mol-1 dm3 and KAssocM = (1.51 +/- 0.07) x 10(2) mol-1 dm3. The ratios of the fluorescence quantum yields for the bound and free substrate (phi b/phi f) were in the range 1.15-1.48. The detection limits under the optimum conditions were 0.381 +/- 0.001 ng cm-3 for the complex 5MH-hydroxypropyl-beta-cyclodextrin in water and 0.290 +/- 0.001 ng cm-3 for the complex M-hydroxypropyl-beta-cyclodextrin in water with 5% of methanol. The recovery of melatonin from pharmaceutical preparations was 98-103% with an RSD of 2%. The recovery from rat pineals was also good. The method is direct, simple and accurate.

Analysis of 5-methoxytryptamine at the femtomole level in the rat and quail brain by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry.

A sensitive method for the measurement of endogenous 5-methoxytryptamine in brain tissue has been developed using capillary column gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry. 5-Methoxytryptamine was first converted to N-[2H3]acetyl-5-methoxytryptamine by reaction with hexa-deuterated acetic anhydride, followed by reaction with pentafluoropropionic anhydride to yield the highly electron-capturing 3,3'-spirocyclic pentafluoro-propionyl indolenine derivative. Quantitative analysis was carried out by selected-ion monitoring of the [M-HF].- and [M-HF-DF].- ion intensity of the 3.3'-spirocyclic pentafluoropropionyl indolenine derivative, using 5-methoxy-[alpha, alpha, beta, beta-2H4]tryptamine as the internal standard. The presence of 5-methoxytryptamine in the brain tissue was demonstrated. In the absence of a monoamine oxidase inhibitor, the mean +/- S.D. levels of 5-methoxytryptamine in the rat and quail whole brain were found to be 30 +/- 6 and 347 +/- 52 pg/g, respectively. The possible physiological functions of 5-methoxytryptamine as a neuromodulator and/or neurotransmitter have to be considered.

Determination of 5-hydroxytryptamine in rat brain regions by gas-liquid chromatography with electron-capture detection.

An assay method for measurement of 5-hydroxytryptamine in rat brain areas is described. The procedure involves extraction with a liquid ion exchanger followed by acetylation and reaction with pentafluoropropionic anhydride. The resultant beta-carboline is separated and quantitated using gas-liquid chromatography with electron-capture detection. The procedure also works well with 5-methoxytryptamine standards, and the tissue samples were checked simultaneously for the presence of this amine. The results indicate that concentrations of 5-methoxytryptamine in all areas studied (brain stem, hypothalamus, frontal cortex, and striatum) are less than 10 ng/g.

Relation of pH to fluorescence of serotonin, melatonin, and other indole compounds reacted with o-phthaldialdehyde.

We distinguished serotonin, malatonin, and other indole compounds by their markedly different fluorescence behavior when heated with o-phthaldialdehyde in different concentration of HCl, or after the subsequent addition of alkali. Fluorescence may increase, disappear, or change from blue to orange-red. Only melatonin developed significant fluorescence (at less than 0.5 mug/liter) when heated with the reagent in 50 mmol/liter HCl. Serotonin and 5-hydroxyindole compounds with a C-3 aliphatic chain lost their blue fluorescence when brought from strong to weakly acid and alkaline pH. Intense reddish fluorescence developed in strongly alkaline solution. C-5 methoxy derivatives, such as melatonin, maintained their blue fluorescence in alkaline solution. Differences in fluorescence color (and RF) also characterized these compounds on silica gel plates. The use of toluene decreased blank fluorescence, while sample preparation in dim light, as often recommended, resulted in diminished and less-stable fluorescence.

High-performance liquid chromatography assay for indorenate in pharmaceutical powders.

A high-performance liquid chromatographic (HPLC) method for quantification of indorenate admixed of pharmaceutical excipients (Pharmatose DCL 21, Povidone USP and Helmcel 200) is described. Indorenate was extracted from the mixtures using a mobile phase composed of acetonitrile and a sodium acetate buffer solution 0.1 M (63:37) and separated from other dissolved components by ion supression-HPLC. The method was standardized using a C-18 column (250 mm x 4.8 mm, i.d., 5 microns). The photometric detector was fixed at 228 or 272 nm depending on the admixed excipients. Validation parameters included linearity, precision, accuracy, reproducibility, and specificity. The method was specific, selective, and capable to distinguish indorenate from their degradation products and the antihypertensive pelanserine.

Comparison of serotonin and 5-methoxytryptamine immunoreactivity in rat raphe nuclei.

We studied the immunoreactivity of 5-methoxytryptamine (MT) and 5-hydroxytryptamine (HT) in the raphe region of rats using specific polyclonal antibodies and the peroxidase/anti-peroxidase (PAP) technique. Overall, the patterns of the specific staining for these two antibodies were found to be the same in this region of the rat brain. The staining reaction was considerably less intense for MT than for HT. Specificity tests were performed using HT, MT and tryptamine (T) conjugates at concentrations of 5 X 10(-8) M for antibodies to HT and 2.5 X 10(-9) M for antibodies to MT. Although the distribution of HT-like and MT-like immunoreactivity broadly overlapped, the results obtained from adsorption-specificity tests confirmed the presence of specific MT staining in the rat raphe.

Analysis of 5-methoxytryptamine in brain by gas chromatography mass spectrometry.

A quantitative gas chromatographic mass spectrometric method using a deuterated analogue as internal standard were developed for the analysis of 5-methoxytryptamine in brain. The internal standard was synthesized in two steps and possessed high isotopic purity. The analytical procedure involves the addition of the internal standard to the homogenizing medium containing the tissue, followed by homogenization, extraction with chloroform and derivatization with pentafluoropropionic anhydride. The identification and quantitation of 5-methoxytryptamine is based on monitoring the ions at m/z 306, 319 and 482 for the pentafluoropropionyl derivative of 5-methoxytryptamine and m/z 308, 322 and 486 for the internal standard. Using this procedure 5-methoxytryptamine was identified and quantitated in the sheep pineal gland. The mean 5-methoxytryptamine level (N = 12) was 545 +/- 180 pmol g-1.

[Biosynthesis of 5- methoxy-N-acetyltryptamine (melatonin) in enterochromaffin cells]. / Biosintez 5-metoksi-N-atsetiltriptamina (melatonina) v énterokhromaffinnykh kletkakh

Chromatographic analysis of the alkaline extract of the gastrointestinal mucosa of rabbits rich in enterochromaffin cells displayed the presence of melatonin (5-methoxy-N-acetyltryptamine) and its precursors (5-oxytryptophane, tryptamine, serotonine, mexamine) in it. Detection of precursors indicated that not a passive accumulation, but an active synthesis of melatonin occurred in the enterochromaffin cells. Epiphysis was not the only place of melatonin synthesis. Functional condition of enterochromaffin cells was largely determined by the extent of physiological and pathological reactions of the organism.

A single radioimmunological assay for serotonin, N-acetylserotonin, 5-methoxytryptamine, and melatonin.

A radioimmunoassay of melatonin using a new iodinated derivative has been developed. Simple chemical treatments have then been designed to convert serotonin, N-acetylserotonin, and 5-methoxytryptamine to melatonin. Thus these four molecules, belonging to the same metabolic pathway, were separately assayed in the same radioimmunological system at the same sensitivity level (0.01 pmol). Some biological results on the circadian variations of melatonin and serotonin in blood, pineal, and miscellaneous brain structures are presented.

[Extraction of serotonin, bufotenin, 5-methoxytryptamine and 5-methoxy-N,N-dimethyltryptamine and their fluorometric determination with o-phthaldialdehyde]. / Extraktion von Serotonin, Bufotenin, 5-Methoxytryptamin und 5-Methoxy-N,N-Dimethyltryptamin und ihre fluorimetrische Bestimmung mit o-Phthaldialdehyd.

For the investigated indolamines, the recovery following extraction with n-butanol and acetic acid ethyl ester from alkaline solution amounted to 80-90%. Using benzene only the two 5-methoxyindolamines were transferred from the alkaline medium into the organic phase. The reaction of the o-phthaldialdehyde with substituted indolamines was optimized in regard to higher fluorimetric detection sensitivity. The lower limit of determination was 2.0 ng for 5HT and 5OHDMT, and 1.0 ng for 5MeOT and 5MeODMT.

Reversed-phase ion-pair partion chromatography of biogenic catecholamines and their alpha-methyl homologues with tributylphosphate as stationary phase.

Ion-pair partition chromatography is applied to the separation of the biogenic catecholamines and their alpha-methyl homologues. A useful selectivity has been obtained using an adduct-forming organic stationary phase (tributylphosphate). The retention of the compounds can be regulated easily by means of the concentration of the counter-ion (the perchlorate ion) in the mobile phase. The selectivity for separation of amines from amino acids can be influenced by changing the pH of the aqueous phase. The phase system shows a good long-term stability and reproducibility with respect to the capacity ratios and the efficiency.