Effects of intraperitoneal administration of hexasodium N,N,N′,N′-ethylenediaminetetramethylenephosphonate on rat bone metabolism

The influence of hexasodium N,N,N′,N′-ethylenediaminetetramethylenephosphonate (EDITEMP.Na₆) on biochemical parameters in bone has been studied to help explain recently reported histological and pathological changes in bone induced by this agent. A single, intraperitoneal (ip) injection of EDITEMP.Na₆ (350 μmol/kg on Day 0) significantly decreased the activity of serum alkaline phosphatase (Alp) in mature male Wistar rats for up to 10 days following the injection. However, in immature rats the initial EDITEMP.Na₆-induced reduction of serum Alp activity preceded a steady increase in serum Alp activity, which was significantly elevated between Days 6 and 13. This increase coincided with a significant increase in bone Alp activity (an indicator of bone formation) on Day 8. Diaphyseal acid phosphatase (Acp) activity (an indicator of bone resorption) was significantly reduced, on Days 4 and 8 but not on Day 1, following treatment with EDITEMP.Na₆. Repeated exposure of immature male Wistar rats to EDITEMP.Na₆ (70 μmol/kg/day, ip for 7 days) also led to a significant and persistent increase in serum and bone Alp activities and a reduction in diaphyseal Acp activity. The data are in accord with published histomorphological evidence of reduced bone resorption and suggest delayed mineralization of osteoid tissue laid down during the treatment with EDITEMP.Na₆. There were only transient and limited changes in bone DNA content and [³H]thymidine incorporation throughout the studies, indicating the absence of marked cytotoxicity or altered bone cell proliferation associated with EDITEMP.Na₆-induced changes in phosphatase enzyme activities.     

Synthesis, characterization, and antimicrobial activity of copper(II) complexes with N,N′-propanediyl-bis-benzenesulfonamide and N,N′-ethanediyl-bis-2-methylbenzenesulfonamide

Copper(II) complexes of new aryldisulfonamides (L ₁  = N,N′-bis[(2-methylphenyl)sulfonyl]ethylenediamine) and L ₂  = N,N′-propanediyl-bis-benzenesulfonamide with 1,10-phenanthroline have been synthesized and characterized by using elemental analyses, FT-IR, LCMS, conductivity, and magnetic susceptibility techniques. The structures of [Cu(phen)₂]L₁ (1) and [CuL₂(phen)₂] (2) compounds have been determined. Complex (1) has also been characterized by single crystal X-ray diffraction. The complex (1) crystallizes in the triclinic system, space group P1, with cell constants a = 12.9353(8) Å, b = 13.8543(9) Å, c = 14.4513(10) Å, α = 103.593(5)°, β = 113.713(5)°, γ = 106.104(5)°, and Z = 1. The antibacterial activities of synthesized compounds were studied against Gram-positive bacteria: Staphylococcus aureus, Bacillus subtilis, and B. cereus and Gram-negative bacteria: Escherichia coli, Pseudomonas aeruginosa, and Yersinia enterocolitica by microdilution (as MICs in μg/mL) and disk diffusion (as diameter zone in mm) method. The biological activity screening showed that (1) has more activity than (2) against the tested bacteria.     

Influence of papaverine derivatives on phosphodiesterase activity,cyclic 3′,5′-AMP levels and relaxing effect on rabbit ileum

Summary The correlations between the relaxing effect of papaverine derivatives, inhibition of low K_m-phosphodiesterase (cAMP-PDE=EC 3.1.4.17) activity and cyclic 3,5-AMP (cAMP) levels in isolated rabbit ileum were investigated. There was a strong correlation between the relaxing effect, inhibition of PDE activity and cAMP content for eupaverine, ethylpapaverine and papaverine. Eupaverine was the most effective relaxing agent (I₅₀=7.5 M) and the most potent inhibitor of PDE activity (K_i=0.6 M), followed by ethylpapaverine (I₅₀=10 M); K_i=0.8 M) and papaverine (I₅₀=20 M; K_i=2 M). In contrast, there was a strong relaxing effect (I₅₀=6 M) but only slight inhibition of PDE activity (K_i=350 M) by tetrahydropapaveroline (THP). The adenylate cyclase stimulating effect of THP which was shown by others is most likely the reason for comparatively higher cAMP levels, which were found to be elevated about seven times over basal levels of 0.35 nmoles/g wet weight, and effective relaxation. Relaxation could be induced by exogenously added cAMP (I₅₀=45 M) and dibutyryl-cAMP (I₅₀=450 M). Our results support the assumption that smooth muscle relaxation in rabbit ileum is mediated by cAMP. Some of these observations have been published in abstract form (Schulz and Berndt, 1972).     

Effects of N,N′-methylene-bis-acrylamide (MBA) on mouse germ cells — sperm count and morphology,and testicular pathology

The sperm count and morphology, and testicular histopathology were studied in mice over a period of 75 days following a single oral administration of 50, 100, and 200 mg/kg N.N-methylene-bis-acrylamide (MBA). With a 50 and 100 mg/kg dose, the sperm abnormality reached a maximum at 30 days, whereas the sperm count reached a minimum at 35 days. The abnormality and decrease in sperm count were both dose dependent. Following the administration of 200 mg/kg MBA, the appearance of abnormal sperm showed a diphase pattern, i.e., first at 7–15 days without any reduction of the sperm count and second at 30 days after treatment. Testicular histopathological changes showed that resting spermatocytes, succeeding leptotene and zygotene spermatocytes were either absent or reduced 1–3 days after treatment with 200 mg/kg MBA. These early histopathological changes seemed to precede both the increase in abnormal sperm and the decrease in sperm count observed 30–35 days post-treatment, and also suggested that resting spermatocytes were most sensitive to MBA exposure among various spermatogenic cells.     

Effect of different oxygen pressures and N,N′-diphenyl-p-phenylenediamine on adriamycin® toxicity to cultured neonatal rat heart myocytes

The effect of different oxygen pressures and the antioxidant DPPD (N,N′-diphenyl-p-phenylenediamine) on Adriamycin (doxorubicin) cytotoxicity in highly purified cardiac myocytes was investigated to evaluate the involvement of free radicals in the mechanism of toxicity. Adriamycin exposure caused a time-dependent decrease in viability measured as intracellular potassium ion release or lactate dehydrogenase retention. Incubation of myocytes in 16, 172 or 834 μM oxygen during exposure to 200 μM Adriamycin for 6 hr killed 13, 42 and 56% of the cells in the respective cultures. DPPD prolonged viability in the latter two oxygen concentrations and protected against lipid peroxidation measured as production of malondialdehyde and 4-hydroxynonenal. Addition of superoxide dismutase decreased the Adriamycin-induced cell killing to 6% after a 4-hr incubation, as compared to 24% in cultures exposed to Adriamycin only. Adriamycin exposure decreased the concentration of reduced glutathione, and the toxicity of the drug was increased when glutathione reductase was inhibited by the addition of BCNU (1,3-bis-2-chloroethyl-1-nitrosourea). No significant effect on Adriamycin toxicity was observed after inhibition of glutathione synthesis by treatment with BSO (buthionine sulfoximine). It is concluded that free radicals play an important role in Adriamycin toxicity to heart myocytes, and that the cell killing mechanism is likely to be related to induction of lipid peroxidation.     

Effect of a novel nicotinic receptor antagonist, N,N′-dodecane-1,12-diyl-bis-3-picolinium dibromide, on nicotine self-administration and hyperactivity in rats

Rationale and objective Recent work has shown that the novel compound N,N′-dodecane-1,12-diyl-bis-3-picolinium dibromide (bPiDDB) may selectively block nicotinic acetylcholine receptors involved in regulating dopamine release. The current experiments examined the acute effect of bPiDDB on nicotine self-administration, sucrose-maintained responding, and nicotine-induced changes in acute and sensitized locomotor activity. Methods Rats were first trained to respond for either nicotine (i.v.) or sucrose pellets using a standard two-lever operant conditioning procedure using a fixed ratio 5 schedule of reinforcement and were then pretreated with bPiDDB (0, 0.3, 1, or 3 mg kg⁻¹) 15 min prior to the session. In separate experiments, rats were assessed for nicotine-induced changes in locomotor activity following pretreatment with bPiDDB (1 or 3 mg kg⁻¹) or mecamylamine (1 mg kg⁻¹); pretreatments were assessed with both acute and repeated nicotine (0.4 mg kg⁻¹) treatment. Results Results showed that bPiDDB dose-dependently decreased nicotine self-administration, but not sucrose-maintained responding. In the locomotor experiments, bPiDDB attenuated the hyperactivity produced by acute and repeated nicotine; however, this effect was not robust compared to mecamylamine. In contrast to mecamylamine, bPiDDB did not block the initial hypoactivity produced by acute nicotine. Conclusion Since bPiDDB decreased nicotine self-administration specifically, this novel nicotinic receptor antagonist may constitute a lead for the development of a clinically useful treatment for tobacco dependence.     

Gonadal Influence on the Toxicity of 2-(2′-Hydroxy-3′,5′-di-tert-butylphenyl) benzotriazole in Rats

Previously, we showed that susceptibility of male rats to the toxicity of an ultraviolet absorber, 2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)benzotriazole (HDBB), was nearly 25 times higher than that of females. In the current study, we investigated the role of sex steroids in the mediation of the gender-related difference using castrated rats. Male and female castrated CD(SD) rats were given HDBB by gavage at 0, 0.5, 2.5, or 12.5 mg/kg/day for 28 days. No deaths, clinical signs of toxicity, or changes in body weight or food consumption were found at any doses. Blood biochemical changes suggestive of hepatic damage, such as increased levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and lactate dehydrogenase, were detected at 12.5 mg/kg/day in males. Absolute and relative liver weight increased at 0.5 mg/kg/day and above in males and at 12.5 mg/kg/day in females. In the liver, histopathological changes, such as nucleolar enlargement, increased mitosis, hypertrophy in hepatocytes, and/or focal necrosis were observed at 0.5 mg/kg/day and above in males, and at 2.5 mg/kg/day and above in females. These findings indicate that castration markedly reduced the gender-related differences in toxicity of HDBB in rats.     

Influence of calcium channel blockers on GABAA receptor

This study was undertaken to address effects of the interactions between calcium transients and serotonergic action on the regulation of sleep architecture and c - Fos expression （as a marker of neuronal activation） in VLPO and TMN induced by pentobarbital （PB） and the influence of Ca^2＋ channel blockers （CCB） on GABAA receptor.     

Evaluation of the anti-inflammatory activity of N,N′-bis(3-dimethylamino-1-phenyl-propylidene)hydrazine dihydrochloride

This study investigated the anti-inflammatory effect of N, N′-bis(3-dimethylamino-1-phenyl-propylidene)hydrazine dihydrochloride, D1, on carrageenan-induced edema. In addition, its effect on hyaluronidase-induced vascular permeability was also tested. D1 was synthesized, and anti-inflammatory activity was determined by carrageenan-induced hind paw edema in rats (n?=?30) at 50, 100, and 200?mg kg^?1 doses of D1 and also a 25?mg kg^?1 dose of indomethacin. The effects of D1 and indomethacin on hyaluronidase-induced capillary permeability were investigated in rabbits (n?=?18) at a 100?mg kg^?1 dose of D1 and 25?mg kg^?1 dose of indomethacin. D1 inhibited carrageenan-induced inflammation by 40, 20, and 10% at 50, 100, and 200?mg kg^?1 doses after 1?h. The inhibitions were 22.5, 32.7, 28.6% and 15.6, 33.4, 8.9% at 2?h and 3?h, respectively. The inhibitions due to indomethacin (25?mg kg^?1 dose) were 67.5, 87.8, and 91.1%, at 1?h, 2?h, and 3?h, respectively. The subcutaneous spreading areas of Trypan blue at 1, 5, 30, and 60?min after subcutaneous injection of hyaluronidase were 172.6?±?41.6, 210.2?±?39.7, 363?±?50, and 400.2?±?46.7?mm² in the D1 (100?mg kg^?1) treated group. The spreading areas at these time periods were 38.8?±?3.7, 48.2?±?4.5, 100.6?±?6.9, and 119.8?±?22.5?mm² in the indomethacin treated group. Our results showed that D1 inhibits carrageenan-induced inflammation in rats. A tendency to decrease the capillary permeability suggested that the mechanism of action of the anti-inflammatory effect of D1 may partly depend on inhibition of the hyaluronidase enzyme.     

Influence of 16β formylation on Na,K-ATPase inhibition by cardiac glycosides

Summary The inhibitory effect of formylated cardiac steroids (gitaloxin and its derivatives) on guinea-pig heart Na, K-ATPase was compared to that of other cardiac steroids with various hydroxy substituents. The decreasing order of potency of aglycones at equilibrium was as follows: gitaloxigenin > digitoxigenin > ouabagenin > digoxigenin > gitoxigenin > diginatigenin. This sequence was different to the sequence of drugs hydrophobic character. The compounds with hydroxy groups in the vicinity of the lactone ring (gitoxigenin, diginatigenin) were less potent than the hydrophilic compound ouabagenin. We propose that intramolecular bonding between 16-OH and the lactone ring contributes to the relatively low potency of gitoxigenin and diginatigenin. The formylation of 16-OH increased the potency of gitoxigenin by a factor of 41. The formylated compound (gitaloxigenin) was 5-fold more potent than digitoxigenin. The 3-glycosylation of digoxigenin lead to pseudo-irreversible inhibitors of Na, K-ATPase. The half-time to achieve the equilibrium (for 5mol/l) was equal to 54 s, 90 s and 108 s respectively for digoxigenin monodigitoxoside, digoxin and desacetyllanatoside C. However, at equilibrium the three glycosides were equipotent, suggesting the existence of steric effects at the sugar site of the receptor. The sequence of potency observed for monodigitoxosides, monodigitalosides and tridigitoxosides after 60 min incubation was similar to that observed for the corresponding aglycones. These results suggest that the strongly negative inductive group 16-OCHO is tightly bound to Na, K-ATPase, possibly to the same receptor site than that which is thought forming hydrogen and ionic bonds with the lactone ring. They show that the high toxicity of gitaloxin in guineapig heart is likely due to its high potency as Na, K-ATPase inhibitor.     

In Vitro Antileishmanial,Trypanocidal, and Mammalian Cell Activities of Diverse N,N′ -Dihetaryl Substituted Diamines and Related Compounds

The leishmaniasis and Chagas diseases constitute a serious public health problem worldwide with few and ineffective treatment options. The search for new antiparasitic candidates at the initial steps of drug discovery and development is still necessary. The synthesis of 22 de novo synthetized N,N′-dihetaryl-alkyldiamine derivatives and in vitro antiparasitic activity were evaluated for the first time against intracellular and extracellular forms of Leishmania (Leishmania) infantum, L. (Viannia) panamensis, L. (Leishmania) amazonensis, and Trypanosoma cruzi. Additionally, the toxicity on mammalian cells was determined. Some of these substituted N,N′-diamines (25–35 % of the tested compounds) showed interesting results against free-living forms of parasites with activities at the inhibitory concentration (IC₅₀) level of 1.96 to 28.83 μM for L. (L.) infantum promastigotes and IC₅₀ of 0.02 to 5.31 μM for T. cruzi epimastigotes. No activity at the IC₅₀ level on intracellular amastigotes of T. cruzi was observed. However, N¹,N²-dibenzylethane-1,2-diamine 5a revealed an important activity against the intracellular amastigotes of L. infantum (IC₅₀ 25.42 μM ±0.33) and L. panamensis (IC₅₀ 58.20 μM ±3.23), while their analogue N¹,N⁴-dibenzylbutane-1,4-diamine 5c resulted in activity only against L. panamensis (IC₅₀ 11.19 μM ±0.20) without toxicity on Vero and THP-1 mammalian cells. The active compounds against intracellular parasites with low toxicity in mammalian cells may be considered for future studies in experimental models.     

Influence of silybin on biophysical properties of phospholipid bilayers1／

AIM: Silybin (silibinin) is major biologically active flavonolignan extracted from milk thistle (Sylibum marianum). Its biological activities include hepato-protection, anticancer properties, and antioxidant- and membrane-stabilizing functions. Although membranes are postulated to be one of the cellular targets for silybin, little is known about its interaction with phospholipid bilayers. METHODS: In the present work, the interactions of silybin with phosphatidylcholine bilayers were studied in detail using fluorescence spectroscopy, microcalorimetry and electron spin resonance techniques. RESULTS: The results showed that silybin interacted with the surface of lipid bilayers. It affected the generalized polarization of the fluorescent probe Prodan, while not influencing the more deeply located Laurdan. Silybin lowered the main phospholipid phase transition temperature as judged by microcalorimetry, and caused the immobilization of spin probe Tempo-palmitate located on the surface of membranes. The mobility of spin probes 5- and 16-doxyl stearic acid was not affected by silybin. Silybin-induced quenching of 1,6-diphenyl-1,3,5-hexatriene fluorescence indicated that some flavonoid molecules partitioned into the hydrophobic region of membranes, which did not change significantly the biophysical properties of the deeper membrane regions. CONCLUSION: Such a behavior of silybin in membranes is in accordance with its postulated biological functions and neglectable side effects of therapies using silybin.     

Influence of δ 9-tetrahydrocannabinol on partial reinforcement effects

Two experiments were performed with rats trained with either continuous reinforcement (food) or random 50% partial reinforcement for running in a straight alley. Half the rats were trained with daily injections of 0.5 mg/kg ⁹-tetrahydrocannabinol (THC) and half with vehicle injections, all animals being extinguished with vehicle injections in Expt. 1 and with THC injections in Expt. 2. The partial reinforcement acquisition effect was abolished by THC during training; the partial reinforcement extinction effect was abolished by THC either during training or during extinction. In these respects THC resembles amylobarbitone and alcohol.     

Protolytic constants of nizatidine,ranitidine and N,N′-dimethyl-2-nitro-1,1-ethenediamine; spectrophotometric and theoretical investigation

The prototropic exchange equilibria of two drugs, nizatidine (I) and ranitidine (II), and also of structurally related the N,N′-dimethyl-2-nitro-1,1-ethenediamine molecule (III) were investigated. From the changes in electronic spectra in media of various acidity several protonation constants were determined. For nizatidine pK values were −0.82, 1.95, and 6.67; for ranitidine pK values were 1.95 and 8.13; and for III was 2.60. The hydroxylation equilibrium constant in strongly alkaline media was determined too. Corresponding pK_a values were 13.23 for I, 13.26 for II and 13.76 for III. Molecular orbital calculations of electronic spectra confirmed that pK 1.95 for I and II, and pK 2.60 for III, are associated with C-protonation of nitroethenediamine fragment, while all pK_a values correspond to the addition of HO⁻ anion at the same double bond.     

Synthesis,characterization, and antibacterial activities of some novel N,N′-disubstituted thiourea, 2-amino thiazole,and imidazole-2-thione derivatives

In the search of bioactive molecules, a series of novel N-substituted thiourea derivatives 3(a–d) are prepared by reaction of the α-amino pyridyl ketone hydrochloride (2a) with the corresponding aryl isothiocyanates. The synthesis of some new 2-amino thiazoles 4(a–d) and imidazole-2-thiones 6(a–d) were attempted by intramolecular cyclization reaction of the N,N′-disubstituted thioureas 3(a–d) and their intermediate ketals 5(a–d) in diluted aqueous acidic and strong acidic mediums. The structure of all newly synthesized compounds was established by analytical and spectral data. The antibacterial studies to all of the synthesized compounds against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis bacteria with Gram-positive and negative strains, as MIC values are reported. Some of these compounds such as 3a,b,d and 4b,d exhibited a good to significant antibacterial activity. Also, all of new synthesized compounds 3,4,6(a–d) were active against Gram-positive S. aureus bacterium. Thus, some of these compounds can emerge as a promising tool for further research work.