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PubMed1985

Formation of N-mononitrosopiperazine in the stomach and its excretion in the urine after oral intake of piperazine.

Piperazine, a secondary amine widely used as an anthelmintic drug, nitrosates rapidly in vitro to form two N-nitrosamines. Anhydrous piperazine and a drug formulation were found to have a content of 0.2 to 20 micrograms of the suspected carcinogen N-mononitrosopiperazine per gram piperazine, but no detectable amounts of the carcinogen N,N'-dinitrosopiperazine. The aim of this study was to investigate the possible nitrosation of the drug piperazine in man. Thirty minutes after oral administration of 480 mg piperazine to four fasting, healthy, male volunteers, gastric juice contained 140 to 230 micrograms/liter N-mononitrosopiperazine as determined by gas chromatography-thermal energy analysis. The total amount produced by endogenous formation in the stomach is estimated to have been 30 to 66 micrograms. N-Mononitrosopiperazine was not detected in blood, but was excreted in the urine, mainly in the first 6 hr (0.07 to 2.1 micrograms) with half of this appearing within 3 hr. Internal acidification of the urine did not affect the excretion or content. N,N'-Dinitrosopiperazine was not found in any sample of gastric juice, blood, or urine. The excretion of piperazine was in accordance with earlier findings. Coadministration of 2 g ascorbic acid resulted in a significant but incomplete and varying inhibition of both the nitrosation in the stomach and the excretion in urine.

Administration, Oral↗

PubMed1997

The influence of high- and low-fibre diets on the activity of piperazine against Oesophagostomum spp. in pigs.

An in vivo study evaluated the effect of diet on the efficacy of piperazine against nodular worms of pigs. Twenty pigs, later allocated into five groups, were each infected (and 37 days later re-infected) with 3000 infective larvae of a mixed isolate of Oesophagostomum dentatum and Oesophagostomum quadrispinulatum. Beginning on day 23 post infection (p.i.), pigs in groups 1 and 2 were fed a low-fibre diet consisting of 70% barley flour and 30% protein concentrate, while pigs in groups 3, 4 and 5 were fed a high-fibre diet consisting of 55% barley flour, 21% oat-husk meal and 24% protein concentrate. On day 42 p.i., pigs in groups 1 and 3 were orally dosed with 200 mg piperazine dihydrochloride (Ascarex D, 53%) per kg bodyweight, the recommended dose, while pigs in group 4 were given 100 mg kg-1. Groups 2 and 5 served as non-treated controls for the respective dietary regimens. Eight days after treatment, the pigs were slaughtered and worms recovered from the caecum and large intestine (divided into five sections) and counted. The mean worm count reduction (WCR) in group 1 (full-dose piperazine with low-fibre diet) was 89.8%, while the high-fibre diet in group 3 increased the WCR to 99.4%. In group 4, where the pigs were fed the high-fibre diet and treated with only 100 mg piperazine kg-1, the WCR was 90.9%, identical to the "low fibre" group 1 treated with twice this piperazine dose. There was a zero efficacy recorded against immature worms in all three treated groups. The high-fibre diet improved the efficacy of piperazine against more pathogenic and generally more tolerant O. quadrispinulatum to 99.2% compared with 84.3% at the low-fibre diet.

Animals↗

PubMed2005

Piperazine-based buffers for liposome coating of capillaries for electrophoresis.

Anionic liposomes can be coated on fused-silica capillaries for electrophoresis in the presence of N-(hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) (HEPES) as background electrolyte (BGE) solution. In this work, the interaction of various compounds with zwitterionic and anionic phospholipid coatings was studied with HEPES at pH 7.4 as BGE solution. The chromatographic and electrophoretic behavior of three test sample solutions (anionic, cationic, and neutral) was investigated for evaluation of the phospholipid coatings. Our results show that hydrophobic interactions between analytes and the phospholipid coating are important for the migration of charged analytes. In addition, the performances of other piperazine-based buffers, i.e., N-(2-hydroxyethyl)piperazine-N'-(2-hydroxypropanesulfonic acid), piperazine-N,N'-bis(2-ethanesulfonic acid), and piperazine-N,N'-bis(hydroxypropane sulfonic acid), at pH 7.4, as liposome solvent and BGE solution were evaluated and compared with the performance of HEPES at pH 7.4. The anionic liposome solution comprised 80/20 mol% phosphatidylcholine/phosphatidylserine. A simple test solution was selected and the chromatographic and electrophoretic migration behavior of the analytes was evaluated. The results show that, in addition to HEPES, other piperazine-based buffers at pH 7.4 are suitable for coating of fused-silica capillaries with anionic liposomes.

Buffers↗

PubMed1998

Piperazine derivatives of butyric acid as differentiating agents in human leukemic cells.

Butyric acid is a potent antineoplastic agent with a well-documented differentiation activity on a wide variety of tumor cells. However, its clinical development is strongly limited by its very short metabolic half-life. In this study we report on the in vitro effects of new original piperazine derivatives of butyric acid on the induction of differentiation and the growth inhibition of human erythroleukemia K562 cells and myeloid leukemia HL60 cells. 1-(2-hydroxyethyl) 4-(1-oxobutyl)-piperazine (HEPB) and [1-(2-hydroxyethyl) 4-(1-oxobutyl)-piperazine] butyrate (HEPDB) were efficient in acting on the differentiation and proliferation of both cell lines, whereas 1-phenyl 4-(1-oxobutyl)-piperazine (PPB) and 1-(3,4-methylene dioxybenzyl) 4-(1-oxobutyl)-piperazine (POB) acted only on proliferation rates. Such derivatives did not induce significant toxicity in mice. These preliminary results should enable, by the development of new series of piperazine derivatives, a better understanding of the mechanisms of action of butyric acid and its analogues on the coupling of growth and differentiation of neoplastic cells.

Animals↗

PubMed2004

Synthesis and biological evaluation of 2-(4-fluorophenoxy)-2-phenyl-ethyl piperazines as serotonin-selective reuptake inhibitors with a potentially improved adverse reaction profile.

Three new 2-(4-fluorophenoxy)-2-phenyl-ethyl piperazines, 1-(3-chlorophenyl)-4-[2-(4-fluorophenoxy)-2-phenylethyl]-piperazine 7, 1-[2-(4-fluorophenoxy)-2-phenylethyl]-4-(2-methoxyphenyl)-piperazine 8, and 1-[2-(4-fluorophenoxy)-2-phenylethyl]-4-(3-trifluoromethylphenyl)-piperazine 9, modeled after the potent antidepressant fluoxetine and coupled with several functionalized piperazines, have been prepared by chemical synthesis as selective serotonin reuptake inhibitors (SSRIs) with a potentially improved adverse reaction profile. Typical SSRIs, although very effective in the treatment of depression, still face the troublesome side effect of sexual dysfunction. A number of pharmacological agents-notably, drugs in the piperazine class-have been used to reverse SSRI-induced sexual dysfunction, and evidence for developing an improved SSRI by coupling a fluoxetine congener with the pharmacophore of a reversal agent holds promise. Preliminary data indicates that the hydrochloride (HCl) salts 10, 11, and 12 each exhibit single-site binding at the site of the serotonin reuptake transporter (SERT). However, each of the three compounds are much less potent than typical SSRIs, showing micromolar (microM) affinity for the SERT with IC(50) values of 1.45 microM, 3.27 microM, and 9.56 microM, respectively. Further biological evaluation of compounds 10, 11, and 12 is needed before definitive conclusions can be made with regard to each compound's potential for use as an SSRI-type candidate which is devoid of sexual side effects. Nevertheless, the initial findings are quite encouraging, thus lending credence to the idea of hybridizing an SSRI congener with that of the pharmacophore of an agent known to reverse or treat SSRI-induced sexual dysfunction.

Binding Sites↗

PubMed2004

Chloroalkyl piperazine and nitrogen mustard porphyrins: synthesis and anticancer activity.

Fifteen new chloroalkyl piperazine and nitrogen mustard porphyrins have been synthesized by the direct condensation of chloroalkyl piperazine, nitrogen mustard benzaldehyde, and pyrrole. Each porphyrin bears 1-4 chloroalkyl piperazine or nitrogen mustard moieties, which have been used as drugs. The Lindsey method was modified to synthesize chloroalkyl piperazine and nitrogen mustard porphyrins. To successfully synthesize chloroalkyl piperazine and nitrogen mustard porphyrins, catalyst acidity was proved to be the key factor, while the ratio of pyrrole to aldehyde had great influence on product yield. The synthetic chloroalkyl piperazine and nitrogen mustard porphyrins were characterized by elementary analysis, MS, (1)H NMR, IR, and UV-vis. Their anticancer activity to bel-7404 liver cancer cells was tested by the MTT assay. Most of the synthetic porphyrins had good anticancer activity toward bel-7404 liver cancer cells in the absence of light. These compounds might be potential anticancer medicines.

Antineoplastic Agents↗

PubMed1975

Antimalarials. Synthesis and antimalarial activity of 1-(4-methoxycinnamoyl)-4-(5-phenyl-4-oxo-2-oxazolin-2-yl)piperazine and derivatives.

The preparation and activity against Plasmodium berghei of derivatives of 1-(4-methoxycinnamoyl)-4-(5-phenyl-4-oxo-2-oxazolin-2-yl)piperazine are described. Replacement of the cinnamoyl group was accomplished by acylation or alkylation of 1-(5-phenyl-4-oxo-2-oxazolin-2-yl)piperazine. Modifications of the 5-phenyl group were prepared either by a sequence of reactions involving mandelic ester-pemoline-piperazine pemoline or by the reaction of 5-aryl-2-thio-2,4-oxazolidinedione with piperazine or N-substituted piperazines. In a similar manner, pemoline was allowed to react with N-arylpiperazine, hexahydro-1H-1,4-diazepine, and 2,6-dimethylpiperazine to provide N-arylpiperazine pemoline derivatives and variations in the piperazine moiety. Several compounds in which the 2-oxazolin-4-one ring was replaced with other heterocyclic rings were prepared as were several open-chain analogs. Five compounds (three of them substituted in the para position of the 5-phenyl group and two N-arylpiperazine pemoline derivatives) were found to be active against Plasmodium berghei. The remaining active compound possessed changes in the cinnamoyl group and substitution on the 5-phenyl group.

Animals↗

PubMed2004

A novel R-stereoselective amidase from Pseudomonas sp. MCI3434 acting on piperazine-2-tert-butylcarboxamide.

A novel amidase acting on (R,S)-piperazine-2-tert-butylcarboxamide was purified from Pseudomonas sp. MCI3434 and characterized. The enzyme acted R-stereoselectively on (R,S)-piperazine-2-tert-butylcarboxamide to yield (R)-piperazine-2-carboxylic acid, and was tentatively named R-amidase. The N-terminal amino acid sequence of the enzyme showed high sequence identity with that deduced from a gene named PA3598 encoding a hypothetical hydrolase in Pseudomonas aeruginosa PAO1. The gene encoding R-amidase was cloned from the genomic DNA of Pseudomonas sp. MCI3434 and sequenced. Analysis of 1332 bp of the genomic DNA revealed the presence of one open reading frame (ramA) which encodes the R-amidase. This enzyme, RamA, is composed of 274 amino acid residues (molecular mass, 30 128 Da), and the deduced amino acid sequence exhibits homology to a carbon-nitrogen hydrolase protein (PP3846) from Pseudomonas putida strain KT2440 (72.6% identity) and PA3598 protein from P. aeruginosa strain PAO1 (65.6% identity) and may be classified into a new subfamily in the carbon-nitrogen hydrolase family consisting of aliphatic amidase, beta-ureidopropionase, carbamylase, nitrilase, and so on. The amount of R-amidase in the supernatant of the sonicated cell-free extract of an Escherichia coli transformant overexpressing the ramA gene was about 30 000 times higher than that of Pseudomonas sp. MCI3434. The intact cells of the E. coli transformant could be used for the R-stereoselective hydrolysis of racemic piperazine-2-tert-butylcarboxamide. The recombinant enzyme was purified to electrophoretic homogeneity from cell-free extract of the E. coli transformant overexpressing the ramA gene. On gel-filtration chromatography, the enzyme appeared to be a monomer. It had maximal activity at 45 degrees C and pH 8.0, and was completely inactivated in the presence of p-chloromercuribenzoate, N-ethylmaleimide, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Hg2+, or Pb2+. RamA had hydrolyzing activity toward the carboxamide compounds, in which amino or imino group is connected to beta- or gamma-carbon, such as beta-alaninamide, (R)-piperazine-2-carboxamide (R)-piperidine-3-carboxamide, D-glutaminamide and (R)-piperazine-2-tert-butylcarboxamide. The enzyme, however, did not act on the other amide substrates for the aliphatic amidase despite its sequence similarity to RamA.

Amidohydrolases↗

PubMed1972

Some pharmacological properties of piperazine.

1. The action of piperazine on mammalian smooth, cardiac and skeletal muscles has been studied.2. Piperazine increased tone and produced a dose dependent contraction of isolated smooth muscle, which was antagonized by atropine.3. With cardiac muscle, piperazine depressed both the rate and force of contraction and was antagonized by atropine. At higher concentrations, a non-specific depression of cardiac muscle was found. The intravenous injection of piperazine produced a transient decrease in both heart rate and blood pressure and this was followed by an increase.4. In about half of the mammalian skeletal muscle preparations, piperazine potentiated the twitch of the muscle evoked by electrical stimulation.5. On the frog neuromuscular preparation, piperazine produced potentiation of the twitch but this was followed first by blockade of the effects of nerve stimulation and then by depression of the effects of direct muscle stimulation.

Animals↗

PubMed1986

Prevalence of specific IgE antibodies against piperazine in employees of a chemical plant.

In 5 out of 72 (7%) workers exposed to the asthma-inducing amine piperazine, specific IgE antibodies against a conjugate between human serum albumin and piperazine were demonstrated with RAST and RAST inhibition techniques. No specific antibodies were found in 64 nonexposed workers at the same plant, and in 60 healthy reference subjects. Eight out of the 72 (11%) exposed employees had unequivocal histories of piperazine-associated asthma, but only 4 of them had specific IgE antibodies against piperazine. However, there was a statistically significant association between specific antibodies and disease, as 4 out of 5 RAST-positive subjects were asthmatics, as compared with 4 out of the 67 RAST-negatives (p = 0.0003). The 4 RAST-positive asthmatics had been exposed to piperazine for between 6 and 168 months before their asthma started, as compared with induction times of less than a month for the 4 RAST-negatives. This discrepancy may reflect different pathogeneses for piperazine-associated asthma; either type-I allergy, pseudo-allergic reactivity or nonspecific irritative effect on the bronchi. The RAST-positive subjects did not differ from other employees as regards smoking habits but had significantly elevated levels of total serum IgE (p = 0.004).

Adult↗

PubMed1987

Lipophilicity and disposition of 1-aryl-piperazines in the rat.

The disposition of eight 1-aryl-piperazines was investigated in rats after i.v. administration. The concentration of 1-aryl-piperazine in body fluids and tissues was determined by h.p.l.c. or electron-capture g.l.c. Correlations of kinetics and physiological parameters with the lipophilicity of each 1-aryl-piperazine, determined by h.p.l.c. retention on a reverse-phase C18 column at neutral pH, were investigated. Binding to rat plasma proteins varied within the series, increasing with lipophilicity. For the majority of the derivatives the blood-to-plasma ratio was close to unity, implying an almost equal distribution between erythrocytes and plasma. The most lipophilic 1-aryl-piperazine of the series partitioned more into erythrocytes. The eight compounds differed widely in Vss and total Cl values and as a general trend both values increased with lipophilicity. The percentage of the dose excreted unchanged in the urine decreased progressively with increasing lipophilicity. 1-Aryl-piperazines were distributed extensively in all the tissues examined, concentrating particularly in the eliminating organs and lung. They easily entered the rat brain, Cmax values generally being reached within five minutes of parenteral injection. 1-Aryl-piperazine brain uptake increased with lipophilicity.

Animals↗

PubMed2006

Occupational asthma due to piperazine citrate.

BACKGROUND: Piperazine is a secondary heterocyclic amine that may give rise to occupational asthma of uncertain mechanism. METHODS: We report on a 42-year-old woman, a process operator in a chemical factory, who developed work-related symptoms of rhinitis and asthma upon exposure to piperazine citrate. She remained symptom free during holidays and days off work. RESULTS: Skin prick test with piperazine citrate was positive. Specific inhalation challenge with piperazine citrate at a concentration of 5 mg/m3 for 30 minutes elicited an isolated late asthmatic response. Airway hyperresponsiveness to methacholine significantly increased 3 hours after the piperazine challenge, preceding the late asthmatic response. CONCLUSION: This patient had developed occupational asthma caused by piperazine, as confirmed by the specific inhalation challenge test, possibly due to an immunological mechanism.

Adult↗

PubMed2006

[Piperazines as model substrate for oxidations].

Piperazines as model substrate for oxidations Piperazine derivatives when being oxidized by mercury-EDTA behave unusually. Due to the reactive cyclic enediamine intermediates as aza-analogous reductones and to the carbonyl compounds resulting from dehydrogenation in the side chain, there exists a high tendency of polymerization. 1-Benzylpiperazines 5a-d generate the piperazine-2,3-diones 8a-d in medium yields. From 1-benzhydrylpiperazine 11 results a mixture of piperazine-2,3-dione 12 and piperazine-3-on 13. The 1,4-bis-substituted piperazines react more differently because of the symmetry and the preferred direction of the dehydrogenation into the cycle. Thus, from 15 and 19 the diones 16 and 20, respectively, were available in very good yields. A mechanism for the reactions is proposed.

Benzyl Compounds↗

PubMedDate not supplied

Experimental teratogenicity of structurally similar compounds with or without piperazine-ring: a preliminary report.

For studying if piperazine-ring plays a role in teratogenicity pairs of compounds of similar structure and action (perphenazine-chloropromazine, chlorcyclizine--thenalidine, haloanisone--haloperiodol) had been selected, where only one of them contained piperazine-ring. The applied single doses were 3.7 X 10(-4) M/kg. Experiments were carried out on Wistar/H-Riop pregnant rats; equimolar doses of three drug-pairs were given orally on the 13th, 14th, or 15th gestational days, respectively. Perphenazine and chlorcyclizine, as alkyl-piperazine derivatives induced cleft palate and micromelia, while chlorpromazine and thenalidine did not. After the methoxyphenyl-piperazine containing substance--haloanisone--micromelia was higher as compared to that containing no piperazine moiety (haloperidol). These results indicate that the piperazine-ring may play an important role in the teratogenicity of drugs in rats.

Animals↗

PubMed1993

Synthesis and pharmacological screening of a group of piperazine derivatives. Analgesic activity.

Fifteen original piperazine derivatives were synthesized: 11 esters of 1-substituted-4-(3'-phenyl-3'-hydroxypropyl)-piperazines with acetic, propionic, benzoic and phenylacetic acids and 4 symmetrical esters of 1,4-bis-(3'-phenyl-3'-hydroxypropyl)-piperazine with acetic, propionic, benzoic and phenylacetic acids. The compounds were tested with respect to their analgesic and behavioural activity, as well as toxicity. Three nociceptive tests were used: chemical intraperitoneal irritation with acetic acid, thermal contact irritation and thermal radiation irritation. The tests were performed on albino mice breed H. All tested compounds were biologically active and showed analgesic effect. The "therapeutic index" was determined on the basis of the mean effective doses (ED50) and the mean lethal doses (LD50). Most favorable "therapeutical" indices were distinguished in 1,4-bis[3'-phenyl-3'-acetoxypropyl]-piperazine (12), 1-benzhydryl-4[3'-benzyloxypropyl]-piperazine (10) and 1-benzhydryl-4[3'-phenyl-3'-phenylacetyloxypropyl]-piperazine (11).

Acetates↗

PubMed1964

MECHANISM OF THE PARALYSING ACTION OF PIPERAZINE ON ASCARIS MUSCLE.

The effects of piperazine on Ascaris muscle cells have been investigated with electrophysiological techniques. These cells have an average resting potential of about 30 mV interrupted by rhythmic spikes of myogenic origin (1 to 7 spikes/sec). With piperazine (10(-3), w/v), the average resting potential increases above 40 mV and the pacemaker activity is suppressed. These changes are similar to those temporarily produced in the same cells by the electrical stimulation of inhibitory nerve fibres. Electrophoretic application of piperazine to different areas of the muscle cells shows that this drug hyperpolarizes their membrane only when applied to the region where both excitatory and inhibitory neuromuscular synapses are located. The degree of muscle hyperpolarization induced by piperazine depends upon the extracellular chloride concentration, decreasing when a fraction of the chloride ions is replaced by the larger, supposedly nonpenetrating, sulphate anions. Piperazine may, therefore, be regarded as a pharmacological analogue of a natural inhibitory transmitter.

Animals↗

PubMed1996

Pharmacological evaluation of prazosin- and doxazosin-related compounds with modified piperazine ring.

New doxazosin-related compound (1-3) with a N,N'-dimethyl alkanediamine chain replacing the piperazine ring, have been synthesized and their pharmacological properties have been tested together with some prazosin analogues (4-8) bearing either a similar structural modification or a substituted piperazine moiety. In the in vitro study, on alpha 1- and alpha 2-adrenoceptors of rat vas deferens tissues, 1-3 displayed high alpha 1-antagonist activity, 2 and 3 being equipotent to doxazosin but markedly less selective in respect to alpha 2-adrenoceptors. Replacement of the piperazine ring with an alkanediamine chain resulted in a strong fall in alpha 1-selectivity, owing to increased alpha 2-antagonist activity, as in the prazosin-related series. In in vivo studies, the antihypertensive activity of tested compounds was investigated on spontaneously hypertensive rats (SHR) following both intragastric (IG) and intraperitoneal (OP) administration. Among the tested compounds, 7 and 8, which conserved a substituted piperazine ring, proved the most interesting drugs displaying a marked hypotensive effect. The other prazosin- and doxazosin-related compounds, in which an alkanediamine chain replaced the piperazine nucleus, showed an antihypertensive activity markedly lower than that of parent compounds, prazosin (CAS 19216-56-9) and doxazosin (CAS 74191-85-8), although a high alpha 1-antagonist activity in in vitro tests was conserved. These results suggest that the piperazine ring of the prazosin- and doxazosin-related compounds, although not crucial for alpha 1-antagonist activity, may play an important role in the antihypertensive effect, probably by influencing the pharmacokinetic properties of the antagonist.

Adrenergic alpha-Antagonists↗

PubMed2004

New designer drug 1-(3,4-methylenedioxybenzyl) piperazine (MDBP): studies on its metabolism and toxicological detection in rat urine using gas chromatography/mass spectrometry.

Studies are described on the metabolism and toxicological analysis of the piperazine-derived designer drug 1-(3,4-methylenedioxybenzyl)piperazine (MDBP) in rat urine using gas chromatography/mass spectrometry (GC/MS). The identified metabolites indicated that MDBP was metabolized by demethylenation and subsequent methylation to N-(4-hydroxy-3-methoxybenzyl)piperazine followed by partial glucuronidation or sulfation. Additionally, degradation of the piperazine moiety to N-(3,4-methylenedioxybenzyl)ethylenediamine and 3,4-methylenedioxybenzylamine and N-dealkylation to piperazine were observed. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid/liquid extraction and microwave-assisted acetylation allowed the detection of MDBP and its above-mentioned metabolites in rat urine after single administration of a dose calculated from the doses commonly taken by drug users. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of MDBP by analysis of human urine.

Animals↗