Absence of bioactivity of lipid derivatives of serotonin.

BACKGROUND: Serotonin (5-HT) and its receptors are present in central, the brain stem, and peripheral, the carotid body, tissues controlling the ventilatory responses to hypoxia. The exact action of serotonin and its nature are, however, unsettled. We hypothesized that the discrepant results on the ventilatory action of serotonin could be caused by the inability of serotonin to penetrate into the brain or the plasma membrane lipid bilayers, the target site of signal transduction cascades, after its exogenous administration. OBJECTIVE: To study the penetrability of novel lipid derivatives of serotonin of varying fatty acid chain length and number of saturated/unsaturated bonds, the oleic, caprylic, and caprolic amides of 5-HT, into the brain, and their functional effects on the hypoxic ventilatory response in awake rats after systemic administration. MATERIAL AND METHODS: Adult Wistar rats were used for the experiments. In the biochemical part of the study, the presence and stability of the compounds tested, after i.p. injection, was assessed in brain extracts using spectrophotometry and thin-layered chromatography. In the functional part, the ventilatory responses to 8 and 12% hypoxia were compared before and 1 h after the compound administration using a whole body plethysmography. RESULTS: The "lipidized" serotonin compounds turned out to be stable in brain extracts in vitro for up to 3 h of the test. However, we could not substantiate the presence of any of the compounds in the brain, with either method used, after i.p. administration. Likewise, none of the compounds had any appreciable effect on the profile of the stimulatory hypoxic ventilatory response. CONCLUSIONS: Synthetically attaching lipophilic groups to the serotonin molecule does not make it penetrate into the brain. The lack of serotonin penetrability likely depends on the planarity of its molecule, as it does not seem to depend on the size, number of carbons or bond saturation of the "lipidized" molecules. Such molecules do not directly interfere with the carotid chemoreceptor-mediated hypoxic ventilatory response. The study failed to substantiate the bioactive potential of the lipid derivatives of serotonin.

Membrane association of N-oleoyl-dopamine in rat brain.

N-oleoyl-dopamine (OLDA) belongs to a novel class of bioactive amides of fatty acids. The compound, a lipid derivative of dopamine, holds promise as a potential prodrug or carrier of dopamine into the brain. In this context, a key issue concerning OLDA is the integrity of the compound once it enters the brain. We addressed this issue in the current study by assessing the propensity of OLDA for hydrolysis in rat brain tissue in vitro. The brains were dissected from surgically anesthetized rats after they had been sacrificed by perfusion with physiological saline through the heart. Membrane fractions of brain tissue were isolated and incubated with 1 mmol/l OLDA. Stability of the OLDA molecule was assessed from the spectrophotometric recordings of OLDA spectra in membrane fractions at hourly time points for up to 24 hours. The methodological assumption was that any major change in the shape of the OLDA spectrum would point to a structural, and thus also possibly functional, alteration of the molecule. We found that the OLDA spectrum remained unchanged in the assays for up to 17 h of incubation. We conclude that OLDA strongly resists hydrolysis in brain membrane fractions. The results suggest that dopamine-like biological effects of OLDA might have to do with the interaction of the integral OLDA compound, rather than a dissociated-off dopamine moiety, with the dopaminergic system.

Alpha-phenylethylamine in illegally produced amphetamine.

The possibility of simultaneous synthesis of alpha-phenylethylamine and amphetamine from mixture of acetophenone and benzylmethylketone was studied. The structures of specific impurities were predicted and these compounds were synthesized and finally found in reaction mixtures, as well as in the final product. The data collected by gas chromatography, proton and carbon magnetic resonance, Fourier transform infrared spectrometry and mass spectrometry are presented.

In vitro propagation of Withania somnifera and isolation of withanolides with immunosuppressive activity.

Withania somnifera plantlets were produced in vitro from the shoot-tip of aseptically germinated seedlings. Culture conditions were optimized using different plant growth regulators which gave rise to 120 shoots from a single bud. The plantlets were then transferred to pots and maintained in greenhouse for 4 months. 90% of these in vitro propagated plantlets survived and showed normal growth. Leaves from these plants were used for isolation of the withanolides. Methanolic extract of leaves from plantlets growing in tissue culture and those transferred to the greenhouse were evaluated for immunomodulatory activity. While the extract from greenhouse samples showed potent immunosuppressive activity, those from tissue cultures samples did not show any activity. Fractionation and characterization of withanolides, using HPLC, NMR, MS methods revealed the presence of withaferin A in the greenhouse samples. Our results indicate that Withania species may require longer time and better differentiation and also natural environment for the production of withaferin A.

Diastereoselective synthesis of 1-benzyltetrahydroisoquinoline derivatives from amino acids via 1,4 chirality transfer. Part 1.

[structure: see text]. L-(-)-phenylalanine, L-(+)-valine, and L-(-)-proline were used in the diastereoselective synthesis of benzyltetrahydroisoquinoline derivatives.

The molecular and crystal structure of (+/-)-1-methyl-7-oxa-norborn-5-ene-2exo,3exo-dicarboxylic acid-anhydride and its enantiodifferentiation in 1H NMR spectroscopy.

The Diels-Alder reaction between 2-methylfuran and maleic anhydride leads to the formation of known racemic title adduct 3. The structure of this compound was confirmed by X-ray crystallography. An efficient enantiodifferentiation of 3 in 1H NMR spectroscopy was observed upon treatment with Eu(hfc)3.

Electrospray ionization, accurate mass measurements and multistage mass spectrometry experiments in the characterization of stereoisomeric isoquinoline alkaloids.

Mass spectrometry has been employed for the characterization of diastereoisomeric isoquinoline alkaloids. Electrospray ionization was used to generate MH(+) ions, and multistage collisionally activated spectra allowed differentiation among the different compounds via specific fragmentation patterns, whose mechanisms have also been elucidated by accurate mass measurements.

Carbonate ion selective electrodes with trifluoroacetophenone derivatives in potentiometric clinical analyser.

Properties of six derivatives of 1-trifluoroacetylbenzene: [4-(n-butyl)- (1), 4-(n-hexadecyl)- (2), 4-dodecyloxy- (3), 4-(n-dodecylsulfonyl)- (4), N,N-dioctyl-4-trifluoroacetylbenzamide (5), octyl-p-trifluoroacetylbenzoate (6)] as neutral carriers for carbonate ion were examined and compared. The sensitivity towards carbonate ion was for (3) pH dependent. This eliminates (3) from practical applications in clinical analysis. When measuring CO(3)(2-) within the physiological range of human blood using as carriers compounds 1 and 2 the interference of chloride must be taken into account. In the case of carriers 4, 5, 6 this effect is negligible. Electrodes with membranes containing as carriers 2, 4, 5 and 6 were tested in an automatic potentiometric clinical analyser Microlyte 6, KONE. To avoid contamination by atmospheric CO(2) of three aqueous standards (TES, NaCl, NaHCO(3)), pH was adjusted by coulomeric generation of H(+) or OH(-) in a system devoid of carbon dioxide. Recovery of HCO(3)(-) calculated from measured CO(3)(2-) and pH, was investigated in a series of aqueous solutions and spiked bovine serum samples. The correlation between added and recovered concentration of HCO(3)(-) was linear with the intercept close to 0 and slope equal to 1 in aqueous solutions for all ligands and in bovine serum samples only in the case of ligand (2).