Synthesis and cytotoxic evaluation of substituted 3-(3′-indolyl-/3′-pyridyl)-isoxazolidines and bis-indoles

Regio- and stereoselective 1,3-dipolar cycloadditions of C-(3-indolyl)-N-phenylnitrone (10) were carried out with different mono-substituted, disubstituted and cyclic dipolarophiles under mono-mode microwave irradiation to obtain substituted 3-(indol-3′-yl)-N-phenyl-isoxazolidines (16–22). Reactions of nitrone (10) with allenic esters under similar conditions afforded, via a domino process, bis-indole derivatives (23a–c) along with compounds 24 and 25. Similarly, reactions of C-(3-pyridyl)-N-phenylnitrone (26) with mono-substituted, disubstituted and cyclic dipolarophiles were carried out in refluxing dry toluene to obtain substituted 3-(3′-pyridyl)-N-phenylisoxazolidines (27–34). Some of the compounds (16f, 18b, 23a, 23c, 27c and 29f) display significant cytotoxicity against a number of human cancer cell lines.     

Synthesis of stable-isotope-labeled N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide and N-(3-dimethylaminopropyl)-N′-ethylurea

N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) is a carbodiimide coupling reagent commonly used for the preparation of amides from carboxylic acids and amines. Because of initial concerns regarding the genotoxicity of EDC and its use in GMP syntheses at Bristol Myers Squibb, the quantitation of residual EDC and its by-product N-(3-dimethylaminopropyl)-N′-ethylurea (EDU) by liquid chromatography–mass spectrometry (LCMS) impurity analysis was required. These analyses required the use of stable-isotope-labeled EDC and EDU to serve as internal standards. To meet this need, stable-isotope-labeled EDC 9 and EDU 10 were prepared from [1,2-¹³C₂] ethylene glycol and [¹³C,¹⁵N] potassium cyanide in overall yields of 6% and 8%, respectively.     

Analytical Method for the Quantification of 2′,3′-Didehydro-3′-Deoxythymidine,a New Anti-Human Immunodeficiency Virus (HIV) Agent,by High-Performance Liquid Chromatography (HPLC) and Ultraviolet (UV) Detection in Rat and Monkey Plasma

Pharmaceutical Research -     

Bioactivation of N-substituted N′-(4-imidazole-ethyl)thioureas by human FMO1 and FMO3

Enzyme kinetic parameters of the bioactivation of thiourea-containing compounds by human flavin-containing monooxygenase enzymes (FMOs) FMO1 and FMO3 were investigated. A microtitre-based adaptation of methodology described for the thiourea-dependent oxidation of thiocholine was used to determine the turnover of thiourea-containing compounds by human FMO1 and FMO3. The results show that major differences in enzyme kinetic parameters for N-substituted N′-(4-imidazole-ethyl)thiourea exist between human FMO3 and human FMO1. Whereas K_m values of N-substituted N′-(4-imidazole-ethyl)thioureas for human FMO3 are all in the millimolar range, the K_m values for human FMO1 range from the low micromolar to the low millimolar range. Furthermore, among a series of N-p-phenyl-substituted N′-(4-imidazole-ethyl)thioureas an interesting structure–activity relationship is evident with both FMO1 and FMO3. Where the K_m decreases with increasing electron-withdrawing capacity of the p-substituent in the case of FMO1, the opposite phenomenon may be the case with FMO3. The k_cat values of the compounds were all comparable for FMO1, averaging 3.03?±?0.56?min^?1, whereas more variation was found for FMO3 (3.71?±?2.01?min^?1). Enzyme kinetic parameters K_m and k_cat/K_m of human FMO1 for N-substituted N′-(4-imidazole-ethyl)thioureas show a high degree of correlation with the results obtained in rat liver microsomes, in which rat FMO1 is the most abundant form, whereas those of human FMO3 do not.     

Effects of cimetidine on adenylate cyclase activity of guinea pig gastric mucosa stimulated by histamine,sodium fluoride and 5′-guanylylimidodiphosphate

Summary Cimetidine, a recently developed histamine H₂-receptor blocking agent has been shown to be a potent inhibitor of histamine-stimulated gastric acid secretion in rat, cat, dog and man. To study the mode of action of cimetidine the modification of the stimulatory effects of histamine, sodium fluoride and 5-guanylylimidodiphosphate by cimetidine on the adenylate cyclase activity of guinea pig gastric mucosa was studied. The effect of cimetidine was also compared to that of metiamide, an older histamine H₂-receptor antagonist. The effect of cimetidine was qualitatively similar to that of metiamide, i.e. a selective blockade of histamine H₂-receptors. Quantitatively cimetidine was about 10-fold more potent than metiamide.     

Stimulation of adenylate cyclase of guinea pig gastric mucosa by histamine,sodium fluoride and 5′-guanylylimidodiphosphate and inhibition by histamine H1- and H2-receptor antagonists in vitro

Summary There are experimental data indicating that cyclic AMP is involved in the regulation of gastric acid secretion in various mammalian species. In a broken cell preparation of guinea pig gastric mucosa the effects of some stimulants of gastric acid secretion on the activity of adenylate cyclase were studied. The basal adenylate cyclase activity was 483±43 pmoles cyclic AMP/mg proteinx10 min. The activity could be stimulated by histamine maximally 5-fold, by sodium fluoride (NaF) maximally 20-fold and by 5-guanylylimidodiphosphate (GMP-PNP) maximally 10-fold. Neither pentagastrin nor carbachol were able to stimulate the adenylate cyclase. Stimulants of adrenergic - or -receptors (phenylephrine, isoproterenol) were also ineffective.The activation of the adenylate cyclase by histamine was inhibited by the histamine H₁-receptor antagonists diphenhydramine and mepyramine as well as by the histamine H₂-receptor antagonist metiamide. On the other hand, the stimulatory action of NaF or GMP-PNP could be antagonized only by high concentrations of dipenhydramine or mepyramine while metiamide showed no antagonizing effect in this respect. Thus this preparation can be used as a tool to determine the activity and specificity of histamine H₂-receptor antagonists.     

Anemia and porphyria caused by N,N′-methylene-bis-acrylamide (MBA) in Mice and rats

The effects of N,N-methylene-bis-acrylamide (MBA), a cross-linking agent, on blood and bone marrow after repeated oral doses, were studied in mice and rats. Body weight, three major elements of the blood — erythrocytes, leucocytes and platelets — reticulocytes and bone marrow cells, were all reduced in either or both animals, especially in mice. Phenobarbital (PB) treatment did not greatly modify the effects of MBA in mice. An increase in free erythrocyte porphyrins and a decrease in ALA-D activity were observed in both animals. Urinary porphyrins were elevated in rats after MBA-dosing. PB-treatment did not significantly affect the elevation of porphyrins. After cessation of the MBA-dosing, all these changes were inclined to be restored to normal levels. Amounts of liver total porphyrins and microsomal P-450, and red cell fragility were within normal ranges in mice.     

Biological actions and molecular effects of resveratrol,pterostilbene, and 3′-hydroxypterostilbene

Stilbenes are a class of polyphenolic compounds, naturally found in a wide variety of dietary sources such as grapes, berries, peanuts, red wine, and some medicinal plants. There are several well-known stilbenes including trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene. The core chemical structure of stilbene compounds is 1,2-diphenylethylene. Recently, stilbenes have attracted extensive attention and interest due to their wide range of health-beneficial effects such as anti-inflammation, -carcinogenic, -diabetes, and -dyslipidemia activities. Moreover, accumulating in vitro and in vivo studies have reported that stilbene compounds act as inducers of multiple cell-death pathways such as apoptosis, cell cycle arrest, and autophagy for chemopreventive and chemotherapeutic agents in several types of cancer cells. The aim of this review is to highlight recent molecular findings and biological actions of trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene.     

Targeting of 3′-Azido 3′-Deoxythymidine (AZT)-Loaded Poly(Isohexylcyanoacrylate) Nanospheres to the Gastrointestinal Mucosa and Associated Lymphoid Tissues

Purpose. The aim of the study was to evaluate the capacity of poly(isohexylcyanoacrylate) nanospheres to concentrate 3-azido 3-deoxythymidine (AZT) in the intestinal epithelium and associated immunocompetent cells, which are known to be one of the major reservoirs of the human immunodeficiency virus (HIV). Methods. The tissue concentration of ³H-radiolabeled AZT in the gastrointestinal (GI) tract was obtained 30 and 90 minutes after intragastric administration to rats at a dose of 0.25 mg AZT/100 g of body weight. The distribution along the intestine was determined. AZT concentrations in the lymph were obtained by lymphatic duct cannulation. Results. Unlike the solution, nanoparticles did concentrate AZT very efficiently in the intestinal mucosa, as well as in the Peyer's patches, and could simultaneously control the release of free AZT. Concentration in Peyer's patches was 4 times higher for nanoparticles, compared with the control solution. The tissue concentration was 30-45 M, which was much higher than the reported IC₅₀ of AZT (0.06-1.36 M) and was regularly distributed along the gastrointestinal tract. Conclusions. Nanoparticles have been shown to be efficient in concentrating AZT in the intestinal epithelium and gut-associated lymphoid tissues, supporting the view that these particles may represent a promising carrier to treat specifically the GI reservoir of HIV.     

Synthesis, stereochemistry, and antimicrobial evaluation of t(3)-isopropyl-r(2), c(6)-di-2′-furanylpiperidin- 4-one and its derivatives

In a wide search program for new and efficient antimicrobial agents, a series of t(3)-isopropyl-r(2),r(6)-di-2′-furanylpiperidin-4-one 1 and its derivatives 2–7 were synthesized; characterized by IR, ¹H NMR, ¹H-¹H COSY, ¹³C NMR, and mass and elemental analysis; and their antibacterial activity against Streptococcus faecalis, Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa and antifungal activity against Candida-6, Candida albicans, Aspergillus niger, Candida-51 and Aspergillus flavus was evaluated. Compound 6 exerted potent in vitro antibacterial activity against B. subtilis while compound 6 exhibited in vitro antifungal activity against Candida-6.     

DNA damage induced by doxorubicin, 4′-epidoxorubicin and their copper(II) complexes

The DNA-damaging activities of doxorubicin (DXR) and 4-epidoxorubicin (4epiDXR) were tested on a covalently closed circular plasmid. In the presence of a reducing agent (sodium borohydride), DXR and 4epiDXR produced similar dose-dependent alterations of the electrophoretic pattern of DNA fragments. Since transition metal ions are known to catalyze this effect, the effects of Cu(II)DXR and Cu(II)epiDXR were also tested. When the Cu(II)-anthracycline complexes were formed at a drug: metal ratio of 21, the effect on DNA was more severe than in the case of the free drugs; since copper ions alone were found to be devoid of activity at the concentrations present in the complexes, the effect is attributed to a direct interaction between the complexes and DNA. Cu(II)4epiDXR proved to be more potent than Cu(II)DXR; this is probably due to the different structures of the two complexes.     

Synthesis and anticonvulsant activity of indolin(5′-bromoindolin)-3′-spiro-1-(1,2,3,4-tetrahydro)-β-carboline and 3-methyl-β-carboline dihydrochlorides

A series of new spiro-condensed indoles have been synthesized and the relationship between their chemical structure and biological activity has been established. Reduction of the oxo group in previously synthesized hydrochlorides of 2′-oxyindolin(5′-bromoindolin)-3?-spiro-1-(1,2,3,4-tetrahydro-β-carboline and 3-methyl-β-carboline followed by treatment with an ether solution of HCl leads to the dihydrochlorides of indolin-(5′-bromoindolin)-3′-spiro-1-(1,2,3,4-tetrahydro-β-carboline and 3-methyl-β-carboline.     

Synthesis and Pharmacological Properties of 1-Aryl-4-(3′4′,5′-trimethoxybenzoyl)piperazines

A series of 1-aryl-4-(3′,4′,5′-trimethoxybenzoyl)piperazines (IIa - IIg) having structures containing 3,4,5-trimethoxybenzoyl fragments were synthesized and characterized. Compounds IIa and IIc - IIg demonstrated weak anxiolytic properties and moderately decreased the spontaneous motor activity in rats. Compound IIb exhibited anxiolytic activity comparable with that of buspirone but, in contrast to this reference drug, increased the motor activity of test animals. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 5, pp. 12 – 14, May, 2005.