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PubMed1997

The effect of membrane surface potential on the permeability of anionic compounds across the apical membrane in human intestinal epithelial (Caco-2) cells.

The effect of membrane surface potential of the apical side on the intracellular uptake of ionic compounds was investigated using the human colon adenocarcinoma cell line (Caco-2). The transepithelial transport of indolepropionic acid and tryptamine was consistent with the uptake behavior shown by rat intestinal brush-border membrane (BBM) vesicles. Imipramine, which diminished the negative charge of the membrane surface (for both Caco-2 and BBM), acted to increase the uptake of the anionic compounds, indolepropionic acid and ceftibuten, and to decrease that of tryptamine (cationic compound) by both the Caco-2 monolayer and the intestinal BBM vesicles at a pH of 7.5. These results suggest that the effects of membrane surface potential on the permeability of ionic compounds were detectable on the Caco-2 cell line as well as the BBM vesicles. On the other hand, the inhibition of H(+)-linked transport and the stimulation of the surface charge-regulated uptake of ceftibuten have occurred simultaneously on the Caco-2 cell line in the presence of imipramine. It seems that the membrane surface charge (negative) plays an important role in the transport process of ionic compounds across the intestinal epithelium.

Adenosine Triphosphate↗
PubMed1976

Biochemical and physiological effects of chlordimeform.

Chlordimeform is a relatively new acaricide/insecticide, whose mode of action we have investigated. It appears to interfere with amine-mediated control of nervous and endocrine systems in a variety of ways. Specifically, chlordimeform causes a build-up of the amines 5-hydroxytryptamine and to a lesser extent norepinephrine in the rat brain in vivo, antagonizes the in vivo action of reserpine in the rat (reserpine depletes amine stores in the CNS), inhibits monoamine oxidase from rat liver in vitro, and causes hypotension in rabbits. In the American cockroach it directly stimulates the heart in situ, acts synergistically with tryptamine in vivo, inhibits amine-N-acetyltransferase from cockroach head in vitro, causes accumulation of indolamines in cockroaches in vivo, and blocks the stimulation of adenylate cyclase by octopamine in the cockroach CNS in situ. It also inhibits tryptamine metabolism in whole mites in vitro.

Amidines↗
PubMed1979

5-Methyltryptophan resistant cells of Catharanthus roseus.

Several cell lines resistant to 5-methyltryptophan were selected from wild type cells of different Catharanthus roseus suspension cultures. The resistant cells had up to 30 times the normal levels of free tryptophan. Despite the increased pool size of tryptophan anthranilate synthetase activity of resistant cells was as sensitive to inhibition by L-tryptophan as wild type cells. The overproduction of tryptophan did not lead to intensified accumulation of tryptamine nor of indole alkaloids. This was supported by a low conversion of tryptophan to tryptamine in vivo and in vitro. The overproduction of one of the primary precursors was evidently not sufficient to stimulate the rate of indole alkaloid synthesis in Catharanthus cells.

Anthranilate Synthase↗
PubMedDate not supplied

The influence of tryptophan and its metabolites upon rabbit lens electrolyte balance.

The effect of tryptophan and three major metabolites of tryptophan on the rabbit lens electrolyte balance was examined. Even at 3 x 10(-3) M tryptophan, tryptamine and xanthurenic acid had no effect on lens sodium, potassium and calcium content after a 20 hr incubation. Small but significant changes in lens sodium and potassium content were induced by 20 hr incubation in 2 x 10(-3) M 3-hydroxy-DL-kynurenine and 10(-3) M hydroxyanthranilic acid. Lens Na, K-ATPase activity was unaffected by 3 x 10(-3) M tryptophan. Tryptamine reduced, to a small extent, Na,K-ATPase activity at 3 x 10(-3) M, but was without effect at 10(-3) M. 3-hydroxy-DL-kynurenine (2 x 10(-3) M) and 3-hydroxyanthranilic acid (10(-3) M) inhibited Na,K-ATPase activity by 27% and 30% respectively. Only 3-hydroxy-DL-kynurenine had a demonstrable effect on 86Rb uptake. It is concluded that, in contrast to findings in the amphibian lens, metabolites of tryptophan have minimal or no detrimental effects upon rabbit lens electrolyte balance under the in vitro conditions of these experiments. However, this does not rule out a long term effect of these compounds should they accumulate in the lens.

Adenosine Triphosphatases↗
PubMed1999

Biogenic amines and sensory changes associated with the microbial flora of Mediterranean gilt-head sea bream (Sparus aurata) stored aerobically at 0, 8, and 15 degrees C.

Changes in the concentrations of tyramine, agmatine, putrescine, cadaverine, spermidine, tryptamine, spermine, histamine, and trimethylamine were studied in parallel with the development of the microbial population during the storage of Mediterranean gilt-head sea bream (Sparus aurata) at three temperatures (0, 8, 15 degrees C). Changes in sensory scores were also recorded. Pseudomonads and H2S-producing bacteria were the dominant microorganisms. Enterobacteriaceae and lactic acid bacteria were also present in the fish microflora. Among the biogenic amines, putrescine and cadaverine were detected when pseudomonads exceeded 10(6) to 10(7) CFU/g. Histamine was produced only in samples stored at 15 degrees C. Tyramine, tryptamine, agmatine, and trimethylamine were absent regardless of the storage temperature.

Aerobiosis↗
PubMed2002

Formation of biogenic amines in a typical semihard Italian cheese.

Given that the concentration of biogenic amines in cheeses depends on variety, age, and type of microflora, a study was undertaken to investigate the formation of these compounds during the ripening of a typical semihard Italian cheese. Tryptamine, phenylethylamine, putrescine, cadaverine, histamine, and tyramine contents were calculated in 30 samples of Montasio cheese characterized by different levels of proteolysis. Histamine and tyramine were the major amines. Tryptamine and phenylethylamine concentrations were very low at all ripening periods. Putrescine and cadaverine were present only in samples with anomalous fermentation processes. The relationship between the total amine content and the proteolytic maturation coefficient was calculated; however, even for higher levels of proteolysis, the biogenic amine content in Montasio cheese was below the level considered potentially toxic.

Amino Acids↗
PubMedDate not supplied

Present and future of 5-HT receptor agonists as antimigraine drugs.

Serotonin (5-hydroxytryptamine; 5-HT) is thought to play an important role in the pathogenesis of migraine. The discovery of the 5-HT1B/1D/1F agonist sumatriptan constitutes a substantial advance in the acute treatment of migraine, though it displays a number of nonnegligible shortcomings. Today, a number of second-generation drugs derived from tryptamine are under advanced clinical development or are about to be marketed worldwide for the acute treatment of migraine. These tryptamine derivatives display partial agonist properties at 5-HT1B/1D receptors. It is not yet clearly established whether these agents represent a major improvement over sumatriptan in therapeutic effectiveness. Most of them also show affinity for 5-ht1F binding sites and have better oral pharmacokinetics than sumatriptan. The acute antimigraine effects of this second-generation of triptans seem to be obtained in largely the same way as with sumatriptan: by cranial vasoconstriction and inhibition of trigeminovascular activation from both peripheral and central projections. Future directions in migraine therapy should focus on agents that exhibit high intrinsic activity at 5-HT1B/1D receptors, offer a good safety profile, and demonstrate long-lasting action which might also be considered in migraine prophylaxis.

Animals↗
PubMed1975

Effect of tryptophan and its metabolites on gluconeogenesis in mammalian tissues.

In parenchymal cells from starved mice L-tryptophan is a potent inhibitor of gluconeogenesis from substrates giving rise to oxaloacetate. Quinolinate yields a different pattern of inhibition and is generally much less effective. Tryptamine, indole 3-acetaldehyde and indole 3-acetate are equally as effective as tryptophan. Tryptamine inhibition alone may be overcome by pargyline; serotonin does not prevent the inhibition due to tryptophan. In kidney slices from starved rats, however, tryptophan has no effect on gluconeogenesis. Indole 3-acetate is also relatively ineffective, but quinolinate is signficiantly more potent than in liver; at 0.1mM, glucose production from lactate is 50% inhibited. Quinolinate is less effective with citric acid cycle substrates; the pattern of inhibition is consistent with a direct action on phosphoenolpyruvate carboxykinase. There is no evidence that glutamate dehydrogenase is simultaneously inhibited.

Animals↗
PubMed1992

In vitro cytostatic activity of some amino acid 4-N-substituted cytosines.

Cytotoxicity of 22 amino acid 4-N-substituted cytosine derivatives was studied on KB and HeLa human tissue cultures. A 4-N-(1H-2-oxo-4 pyrimidyl)-tryptamine with ED50 activity values of 0.145 x 10(-3) mole/l and ED0 = 0.4 x 10(-5) mole/l showed the highest cytotoxic activity and was qualified for further in vivo investigation. The secondary modification of tryptamine substituent seems to be a determining factor of the cytotoxic activity of 4-N-pyrimidinyl amino acids. The activity of the investigated compounds was inversely dependent on their solubility limited by the results of the solubility-activity relationship analysis.

Cell Division↗
PubMed1977

A study of antidepressant activity of some indole alkylamines.

The antidepressant characteristics of three indole alkylamines were investigated and compared with phenelzine and imipramine by utilising specific pharmacological tools like reserpine, amphetamine, tryptamine and tetrabenazine for determining their possible mechanism of action. Amongst the three indole compounds investigated, indole-3-(2-aminopropyl)-acetate (U-14 164E), indole-3(2-aminobutyl)-d-acetate (u-17 312E) and beta-phenethylhydrazine (phenelzine) produced complete antagonism to reserpine induced sedation, hypothermia as well as facilitation of convulsive seizures. Some of these features suggest that MAO inhibition might be a common mechanism of action of these indoles. The potentiation of CNS effects of tryptamine by these compounds is an outstanding feature of MAO inhibitors, while imipramine is ineffective. Qualitative differences between these indoles and imipramine are evident in the tetrabenazine test. The potentiation of amphetamine induced motor excitation and pentobarbitone narcosis has been explained.

Analgesia↗
PubMed1988

Molecular determinants for recognition of RU 24969 analogs at central 5-hydroxytryptamine recognition sites: use of a bilinear function and substituent volumes to describe steric fit.

The putative serotonin (5-HT) agonist RU 24969 [5-methoxy-3-1,2,3,6-tetrahydropyridin-4-yl)indole; 5-MeO-THPI] has been extensively used in the study and classification of 5-HT receptors. In order to study molecular determinants for recognition of THPIs at central 5-HT recognition sites, about 25 additional THPI derivatives were synthesized, incorporating, among others, 16 different indole-5-substituents and three different pyridine-N substituents in various combinations. Two saturated derivatives (piperidin-4-ylindoles) and two 2-methyl analogs were also included. Binding affinities at 5-HT1A, 5-HT2, and total 5-HT1 sites were obtained and the data were incorporated in quantitative structure-activity relationships (QSARs) using a combined linear free energy/molecular modeling approach. The QSAR analyses suggest distinct differences in the structural features that determine optimal potency at 5-HT1A sites versus those directing optimal potency for 5-HT2 sites. The parameter of the indole-5 substituent that almost exclusively determines potency for 5-HT1A sites is volume, the optimal size being about 24 cubic angstroms (calculated by fitting the activity versus volume data to a bilinear function). This is approximately the size of a carboxamide group. In contrast, at the 5-HT2 site both volume and hydrophobicity play major but opposing roles for the 5-substituent. A balance between the smallest possible volume and the greatest possible hydrophobicity is required for maximal 5-HT2 potency. Benzyl groups on the indole-1 or pyridyl-1 positions also favor potency at the 5-HT2 site (probably largely due to increased hydrophobic binding) while decreasing potency at the 5-HT1A site. A minor electronic contribution to the QSARs involving the charge on the indole 5-carbon is of opposite sign for 5-HT1A versus 5-HT2 sites and thus may also be useful for selective drug design. The data are consistent with the possibility that the indole and pyridyl rings are in a coplanar configuration when binding at both 5-HT1A and 5-HT2 sites, because the indole-2-methyl substituent, which provides a large energy barrier to the coplanar configuration, greatly reduces the potency of THPIs at both binding sites. Similarities in analog selectivity patterns suggest that the indolic portion of these compounds binds similarly to that of other indole derivatives such as tryptamines; thus, it is possible that optimally selective substituents predicted by these QSARs may be extrapolated to tryptamines and other indoles.

Animals↗
PubMed1987

In-vitro assays to detect alkylating and mutagenic activities of dietary components nitrosated in situ.

Nitrosation of dietary components has been combined with the 4-(para-nitrobenzyl)pyridine (NBP) colorimetric test for screening alkylating agents and with the Ames test for the detection of mutagenic activity. This allowed the investigation of short-lived nitrosation products of dietary components which generate electrophilic degradation products requiring no metabolic activation (natural amino acids and some derivatives, ureas, guanidines, primary alkyl and aryl amines). In a first system, precursor, nitrous acid and NBP were present simultaneously. All amino acids tested, except glutamic acid and glutamine, gave positive results. The reactivities spanned more than three orders of magnitude, with the aromatic amino acids and methionine the most active; two primary amines, tryptamine and histamine, were also strongly reactive. All guanidines tested, except the amino acid arginine, gave negative results. A second system consisted of two phases: NBP was added only after destruction of residual nitrite and adjustment of the pH to neutrality. This system was useful for the study of ureas, which are stable in acid but not in neutral media. The range of responses covered more than two orders of magnitude. Most amino acids and primary amines also gave positive results, but could be assessed only after analysing the kinetics of the competing reactions and choosing appropriate reaction times. In a third system, Salmonella typhimurium strain TA100 replaced NBP. Representatives of the class of amino acids, ureas, the primary amine tryptamine, and aniline became highly mutagenic upon nitrosation. Methylguanidine was only weakly mutagenic under the present assay conditions. The results indicate that further studies with unstable nitrosation products of dietary components are required to understand more thoroughly the role of endogenous nitrosation in gastric cancer.

Alkylating Agents↗
PubMed1979

Some properties of 5-hydroxytryptamine receptors in the hindquarters of the rat.

1 The rat hindquarter preparation, as described, responds with reproducible vasoconstriction to noradrenaline and tryptamines. 2 The receptors involved in these responses are distinct. 3 Evidence of heterogeneity of tryptamine receptors was not obtained. 4 The 5-hydroxytryptamine (5-HT) antagonists, methysergide and cyproheptadine, although very potent, displayed antagonism of a non-competitive type whereas a series of phenothiazines and phentolamine displayed competitive antagonism against 5-HT. 5 For the phenothiazines the order of increasing potency was promazine less than chlorpromazine less than triflupromazine.

Animals↗
PubMed1983

Ketanserin in hypertension. Early clinical evaluation and dose finding study of a new 5-HT2 receptor antagonist.

Ketanserin, a new 5-hydroxy-tryptamine antagonist, was given at three different dosage levels (double-blind, randomized) in a dose finding study for 2 months to 31 patients with mild to moderately severe essential hypertension. Treatment with ketanserin was then continued until 9 months had been completed. A significant antihypertensive effect was demonstrated at daily dosages of 20 mg t.i.d. or 40 mg t.i.d. The antihypertensive effect was similar to that of previous multiple drug treatment with conventional drugs. However, 60 mg t.i.d. was not acceptable, at least not as initial dosage. At this dose level, 8 out of 10 patients had to be withdrawn from the study during the initial phase due to unwanted effects. It is conceivable that alpha 1-adrenoceptor blockade may have played a role at this dose level, since postural reactions were observed which was otherwise not the case during this study. Ketanserin is a new and interesting alternative in the treatment of hypertension. At the same time it offers a tool by which the role of 5-hydroxy-tryptamine in the regulation of arterial pressure can be investigated.

Adult↗
PubMed1984

Is 5-HT a mediator in the motor control of the feline pylorus?

Since serotonin (5-HT) is a potent spasmogen of pyloric smooth muscle in vivo, and since it is released on electrical stimulation of extrinsic nerves to the gut, the amine may mediate the excitatory motor responses elicited by vagal or splanchnic stimulation. In this study in cats intra-arterial administration of 5-HT to the stomach evoked a dose-dependent pyloric contraction, which was efficiently antagonized by Ketanserin, a peripheral 5-HT2 receptor antagonist. Such treatment did not affect the vagally or splanchnically induced pyloric motor responses, whereas the blood pressure reaction on splanchnic stimulation was greatly reduced. Therefore, 5-HT does not seem to be essential for the extrinsic neural control of pyloric motility. On the other hand, by means of immunocytochemistry, using a 5-HT antiserum, varicose nerve fibres with tryptamine-like immunofluorescence were demonstrated not only in the myenteric plexus and circular muscle layer but also in vascular nerve terminals of the feline pylorus. The function of these tryptamine-containing nerves is still unclear.

Animals↗
PubMed1978

Preliminary studies of the sodium borohydride stabilizable binding of phenylethylamine and tyramine to brain preparations.

The borohydride stabilizable binding of 2-phenylethylamine and p-tyramine to mouse brain homogenates was compared to that of tryptamine and of serotonin. The highest binding was found to be that of tryptamine, followed by that of serotonin, tyramine, and phenylethylamine. The stabilizable binding of phenylethylamine to calf midbrain (including corpus striatum) homogenates and synaptic membranes was decreased by dopamine; this amine and D-amphetamine also decreased the stabilizable binding of tyramine to rat brain homogenates. The subsynaptosomal distribution of the binding of phenylethylamine to synaptic calf midbrain fractions was also investigated. The highest binding capacity was found in the 0.8 M fraction, rich in myelin.

Animals↗
PubMed1983

High pressure liquid chromatographic determination of putrefactive amines in foods.

A high pressure liquid chromatographic (HPLC) procedure is described for determining the following putrefactive amines: histamine, tyramine, putrescine, cadaverine, tryptamine, and beta-phenylethylamine. The amines were extracted from tuna or cheese with methanol. Further cleanup was performed by sequential extractions with butanol and HCl. The acid extract was dried, and residues were derivatized with dansyl chloride. HPLC separations were performed on an Ultrasphere-ODS column at 33 degrees C. A gradient elution program was used; the total elution time was less than 17 min. Linear standard curves with high correlation coefficients were obtained. The procedure allowed good recoveries of histamine, tyramine, putrescine, and cadaverine; recoveries of tryptamine and beta-phenylethylamine were lower but constant. With this method, some swiss cheese samples were found to contain considerable amounts of histamine, tyramine, putrescine, cadaverine, and beta-phenylethylamine. Canned tuna samples had very low levels of these amines. Since the presence of amines at high levels has been associated with tuna decomposition, this method may be useful in identifying decomposed fish.

Amines↗