Elucidating the Distribution of Plant Metabolites from Native Tissues with Laser Desorption Low-Temperature Plasma Mass Spectrometry Imaging.

Secondary metabolites of plants have important biological functions, which often depend on their localization in tissues. Ideally, a fresh untreated material should be directly analyzed to obtain a realistic view of the true sample chemistry. Therefore, there is a large interest for ambient mass-spectrometry-based imaging (MSI) methods. Our aim was to simplify this technology and to find an optimal combination of desorption/ionization principles for a fast ambient MSI of macroscopic plant samples. We coupled a 405 nm continuous wave (CW) ultraviolet (UV) diode laser to a three-dimensionally (3D) printed low-temperature plasma (LTP) probe. By moving the sample with a RepRap-based sampling stage, we could perform imaging of samples up to 16 × 16 cm2. We demonstrate the system performance by mapping mescaline in a San Pedro cactus ( Echinopsis pachanoi) cross section, tropane alkaloids in jimsonweed ( Datura stramonium) fruits and seeds, and nicotine in tobacco ( Nicotiana tabacum) seedlings. In all cases, the anatomical regions of enriched compound concentrations were correctly depicted. The modular design of the laser desorption (LD)-LTP MSI platform, which is mainly assembled from commercial and 3D-printed components, facilitates its adoption by other research groups. The use of the CW-UV laser for desorption enables fast imaging measurements. A complete tobacco seedling with an image size of 9.2 × 15.0 mm2 was analyzed at a pixel size of 100 × 100 µm2 (14 043 mass scans), in less than 2 h. Natural products can be measured directly from native tissues, which inspires a broad use of LD-LTP MSI in plant chemistry studies.

Pharmacokinetic and Pharmacodynamic Aspects of Peyote and Mescaline: Clinical and Forensic Repercussions.

BACKGROUND: Mescaline (3,4,5-trimethoxyphenethylamine), mainly found in the Peyote cactus (Lophophora williamsii), is one of the oldest known hallucinogenic agents that influence human and animal behavior, but its psychoactive mechanisms remain poorly understood. OBJECTIVES: This article aims to fully review pharmacokinetics and pharmacodynamics of mescaline, focusing on the in vivo and in vitro metabolic profile of the drug and its implications for the variability of response. METHODS: Mescaline pharmacokinetic and pharmacodynamic aspects were searched in books and in PubMed (U.S. National Library of Medicine) without a limiting period. Biological effects of other compounds found in peyote were also reviewed. RESULTS: Although its illicit administration is less common, in comparison with cocaine and Cannabis, it has been extensively described in adolescents and young adults, and licit consumption often occurs in religious and therapeutic rituals practiced by the Native American Church. Its pharmacodynamic mechanisms of action are primarily attributed to the interaction with the serotonergic 5-HT2A-C receptors, and therefore clinical effects are similar to those elicited by other psychoactive substances, such as lysergic acid diethylamide (LSD) and psilocybin, which include euphoria, hallucinations, depersonalization and psychoses. Moreover, as a phenethylamine derivative, signs and symptoms are consistent with a sympathomimetic effect. Mescaline is mainly metabolized into trimethoxyphenylacetic acid by oxidative deamination but several minor metabolites with possible clinical and forensic repercussions have also been reported. CONCLUSION: Most reports concerning mescaline were presented in a complete absence of exposure confirmation, since toxicological analysis is not widely available. Addiction and dependence are practically absent and it is clear that most intoxications appear to be mild and are unlikely to produce lifethreatening symptoms, which favors the contemporary interest in the therapeutic potential of the drugs of the class.

Rapeseed or linseed in grass-based diets: effects on conjugated linoleic and conjugated linolenic acid isomers in milk fat from Holstein cows over 2 consecutive lactations.

Changes in the distribution of conjugated linoleic (CLA) and conjugated linolenic (CLnA) acid isomers in milk from Holstein cows in response to 4 different oilseed supplements rich in either cis-9 18:1 or 18:3n-3 were determined over 2 consecutive lactations in 58 and 35 cows during the first and second years, respectively. For the first 5 wk of the first lactation, all cows were fed the same diet. Thereafter, cows received 1 of 5 treatments for 2 consecutive lactations, including the prepartum period. Treatments comprised the basal diet with no additional lipid, or supplements of extruded linseeds (EL), extruded rapeseeds (ER), cold-pressed fat-rich rapeseed meal, or whole unprocessed rapeseeds to provide 2.5 to 3.0% of additional oil in diet dry matter. During indoor periods, cows were housed and received a mixture (3:1, wt/wt) of grass silage and hay, whereas cows were at pasture during outdoor periods. Over the entire study, EL resulted in the enrichment of ∆11,13 CLA, ∆12,14 CLA, trans-9,trans-11 CLA, trans-13,trans-15 CLA, ∆9,11,15 CLnA, and cis-9,trans-11,trans-13 CLnA (identified for the first time in bovine milk fat) in milk fat, whereas ER and cold-pressed fat-rich rapeseed meal in particular, increased milk fat trans-7,cis-9 CLA concentration. With the exception of the first indoor period, whole unprocessed rapeseeds decreased cis-9,trans-11 CLA, trans-9,cis-11 CLA, and trans-10,trans-12 CLA abundance. During the second indoor period, EL increased milk trans-9,cis-11 CLA and trans-10,cis-12 CLA concentrations, but the increases in cis-9,trans-11 CLA, cis-12,trans-14 CLA, trans-11,cis-13 CLA, and cis-9,trans-11,cis-15 CLnA concentrations to EL and ER were lower for the second than first indoor period. In contrast to the indoor periods, EL and ER decreased milk cis-9,trans-11 CLA, trans-9,cis-11 CLA, and trans-10,cis-12 CLA concentrations at pasture. The extent of changes in the relative distribution and abundance of CLA and CLnA isomers in milk fat were related to the nature (rapeseed or linseed) and form of oilseed (extruded, cold-pressed fat-rich meal or whole unprocessed) supplement and their interactions with the composition of the basal diet (conserved grass or pasture and dietary starch content). Furthermore, milk fat CLA and CLnA responses to treatments were repeatable between both outdoor periods. Variations in milk fat content and yield measured during the entire study were significantly and inversely associated with milk trans-10 18:1, trans-10,cis-12 CLA, and in particular, trans-9,cis-11 CLA concentrations.

3,4,5-Trimethoxyphenylacetaldehyde, an intermediate metabolite of mescaline, is a substrate for microsomal aldehyde oxygenase in the mouse liver.

3,4,5-Trimethoxyphenylacetaldehyde, an intermediate metabolite of mescaline, was oxidized to 3,4,5-trimethoxyphenylacetic acid by mouse hepatic microsomes. The reaction was NADPH-dependent, and inhibited by SKF 525-A, metyrapone and disulfiram. A P450 isozyme in mouse hepatic microsomes, P450 MUT-2 (CYP2C29), catalyzed the reaction (0.96 nmol/min/nmol P450) in which NADPH and NADPH-cytochrome c reductase were essential for the catalytic activity. The reaction was confirmed to be an oxygenation since molecular oxygen was incorporated into the carboxylic acid metabolite formed under oxygen-18 gas by GC-MS analysis. By addition of antibody against CYP2C29 to the microsomes (3.2 mg/mg microsomal protein) the MALDO activity was inhibited by 35% of the control value with preimmune serum, suggesting that CYP2C29 or an immunologically-related isozyme(s) plays a major role in the NADPH-dependent oxidation of 3,4,5-trimethoxyphenylacetaldehyde to 3,4,5-trimethoxyphenylacetic acid by mouse hepatic microsomes. Pharmacological experiments on mescaline and its deaminated metabolites using mice indicated that the metabolites were much less active or were inactive in cataleptogenic effect and pentobarbital-induced sleep prolongation as compared with the parent compound.

Demethylation of C14 2,3,4-trimethoxyphenylethylamine in schizophrenics before and after L-methionine loading.

Demethylation was compared in acute and chronic schizophrenics and in non-schizophrenics by the administration of C14 labelled 2,3,4-trimethoxyphenylethylamine (TMPEA). The results did not show a significant difference in the urinary levels of the monodemethylated catabolites of TMPEA among any groups of patients. However, there was a significant decrease in demethylation in untreated chronic schizophrenics after ten days of L-methionine orally, whereas the non-schizophrenic group similarly given methionine did not change. This suggests the possibility of a biological weakness in schizophrenia.

Pharmacokinetic parameters of mescaline in rabbits.

By means of a highly specific and sensitive mass fragmentographic method mescaline was measured in rabbit plasma samples, taken at various points after an i.v. injection. The pharmacokinetic behaviour conformed to the two-compartment open model. Half-life times of alpha and beta phases, velocity constants and steady-state distribution volumes of four subjects are reported.

Neurolepticlike actions of l-methadone: effect on mescaline-induced altered behavior and on tissue levels of mescaline in mice.

Mice were injected ip with either saline, l-methadone (2.5, 5, 20 mg/kg), perphenazine (1, 10, 15 mg/kg), or chlorprothixene (1.25, 2.5, 15 mg/kg) 30 min prior to mescaline-14C (25 mg/kg). Mescaline-induced behavioral changes such as agitation, excitement, slight increase in ventilation, and fright to sound stimuli were prevented by all doses of three drugs, and head-shaking, scratching, and locomotor-increasing effects by 5 and 20 mg/kg methadone and by all doses of both neuroleptics. Catalepticlike state and moderate to marked hypothermia induced by all doses of chlorprothixene, 10 and 15 mg/kg perphenazine, and 20 mg/kg methadone were not reversed by mescaline. Chlorprothixene (all doses), perphenazine (10, 15 mg/kg), and methadone (5, 20 mg/kg) caused marked retention of mescaline and its deaminated metabolite, 3, 4, 5-trimethoxyphenyl acetic acid in both brain and plasma. The fact that relatively higher doses of methadone than neuroleptics are needed to ensure effective antagonism to mescaline action tends to indicate a less specific interaction of the opiate with the neuroleptic/dopamine receptor proposed for central mescaline effects.

3,4,5-Trimethoxybenzoic acid, a new mescaline metabolite in humans.

After ingestion of 400 mg of mescaline sulfate by human volunteers, 3,4,5-trimethoxybenzoic acid was isolated from urine and identified by gas chromatography-mass spectrometry. The amount of this anionic mescaline metabolite was found to be very low as compared with that of the well-konwn 3,4,5-trimethoxyphenylacetic acid. The significance of this finding is discussed.

3H-metaraminol releasing action of mescaline from rat hypothalamus in vitro.

The amine releasing action of mescaline was investigated in rat isolated hypothalamus labeled with 3H-metaraminol. Mescaline had no effect on the uptake of 3H-metaraminol but produced its release in a concentration-related manner. 4 x 10(-4) M mescaline, which produced submaximal effects was used for subsequent experiments. 3 x 10(-5) M cocaine had no effect on the 3H-metaraminol releasing action of mescaline. Mescaline was fully effective in Ca2+-free medium while 6 x 10(-2) M KCl was ineffective. 3 x 10(-7) M tetrodotoxin or 6 x 10(-5) M lidocaine partially blocked mescaline-induced release but substantially or completely blocked 3 x 10(-2) M KCl-induced release. Prior exposure of hypothalamus to 3 x 10(-4) M tyramine reduced the releasing action of mescaline. Thus, mescaline appears to release 3H-metaraminol both by Ca2+-independent (tyramine-like) and Ca2+-dependent (lidocaine-sensitive) mechanisms. 3 x 10(-4) M tyramine and 6 x 10(-2) M KCl released 14C from control hypothalamus labelled with 14C-mescaline, but not from reserpinized hypothalamus. The amounts of 14C recovered in 14C-mescaline labeled control and reserpinized hypothalamus at the end of 50 min of efflux were similar suggesting a poor retention of 14C-mescaline by storage particles.

A dehydrogenase system to demonstrate oxidation of amphetamine and related compounds by rat brain homogenate.

Amphetamine, ephedrine, mescaline and chlorpromazine act as substrate for dehydrogenase system of rat brain homogenate. This system appears quite different from the usual deaminating process of these compounds, which required NADP and oxygen. The present system proceeds more rapidly in anaerobic condition.

[Metabolism of fluorinated mescallins by Pieris brassicae (Insect, Lepidoptera) (author's transl)]. / Etude du métabolisme de mescalines fluorées par Pieris brassicae (insecte, Lépidoptère)

The action of alpha-fluorinated mescalins on induction of diapause in the cabbage butterfly, Pieris brassicae, has been studied. The introduction of fluorine into mescalin has no influence on this activity. This result suggests solvolysis of fluorine and in vivo formation of a common ethylimine intermediate. Activity decreases, however, with substitution of the nitrogen.

Disposition of 14C-mescaline by rabbit lung.

Metabolism of mescaline by several rabbit tissues was examined in vitro. Mescaline-oxidizing activity (micromoles per milligram of protein/15 min) of lung homogenates was 4 times greater than that of either liver or kidney. Brain and plasma each had comparatively little capacity to metabolize mescaline. Mescaline metabolism in vitro was sensitive to inhibition by semicarbazide. Removal of mescaline from the medium perfusing the isolated rabbit lung was explained by intrapulmonary metabolism. Semicarbazide (10(-3) M pargyline. Semicarbazide-treated lungs accumulated more mescaline than did untreated lungs. Mescaline efflux from lung was slower than that of its metabolite. These results indicate that the intact lung removes perfused mescaline and may be important in the disposition of circulating mescaline in vivo.