Spectrophotometric determination of phosphate using lanthanum chloranilate

The spectrophotometric determination of phosphate using lanthanum chloranilate has been investigated. It is possible to determine 3–300 ppm of phosphate with an accuracy of ±2%, if suitable conditions are chosen. Chloride or nitrate ions do not interfere up to 400 ppm. Interference from sulphate ion can be compensated for by adding a large amount of sulphate both to the sample and to the standard solutions. This method is simpler, has less critical reaction conditions, and develops a much more stable coloration than the conventional heteropolyacid methods.     

Construction of pyrimido[5,4-e]-as-triazine,purine, v-triazolo-[4,5-d]pyrimidine and pyrazolo[3,4-d]pyrimidine ring systems from 5-arylazo-6-arylidenehydrazino-1,3-dimethyluracils

Reaction of 5-arylazo-6-arylidenehydrazino-1,3-dimethyluracils (II), prepared by the treatment of 6-aryl-idenehydrazino-1,3-dimethyluracils (I) with diazotized arylamines, with dimethylformamide dimethylacetal resulted in the formation of pyrimido[5,4-e]-as-triazine (V) system, while the thermolysis of II resulted in the formation of purine (X), v-triazolo[4,5-d]pyrimidine (XII), and pyrazolo[3,4-d]pyrimidine (XIV, XIX) systems in lieu of the expected V. Reasonable mechanisms have been proposed for the formation of the various ring systems in these reactions.     

A new method for the synthesis of novel 6-quinoxalinylpyrazolo[5,1-c][1,2,4]triazines

The reaction of the quinoxaline 1 with 4-ethoxycarbonyl-1H-pyrazole-5-diazonium chloride 7 at room temperature gave 3-[α-(4-ethoxycarbonyl-1H-pyrazol-5-ylhydrazono)methoxycarbonylmethyl]-2-oxo-1,2-dihydroquinoxaline 8. The pmr spectrum of 8 in deuteriodimethylsulfoxide supported the presence of two tautomers 8-I and 8-II. Refluxing of 8 in N,N-dimethylformamide or acetic acid resulted in cyclization to afford 8-ethoxycarbonyl-4-oxo-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)-1,4-dihydropyrazolo[5,1-c][1,2,4]triazine 9. Compound 9 was also obtained directly by the reaction of 1 with 7 under reflux in better yield. The reaction of 9 with hydrazine hydrate provided the hydrazinium salt 10 , while the reactions of 9 with triethyl and trimethyl orthoformates in the presence of 1,8-diazabicyclo[5,4,0]-7-undecene produced 8-ethoxycarbonyl-4-ethoxyl-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)pyrazolo[5,1-c][1,2,4]triazine 11a and 8-ethoxycarbonyl-4-methoxyl-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)pyrazolo[5,1-c][1,2,4]triazine 11b , respectively. The chlorination of 11a with phosphoryl chloride gave 3-(3-chloroquinoxalin-2-yl)-8-ethoxycarbonyl-4-ethoxylpyrazolo[5,1-c]-[1,2,4]triazine 12 , whose reaction with morpholine afforded 8-ethoxycarbonyl-4-ethoxyl-3-[3-(morpholin-4-yl)-quinoxalin-2-yl]pyrazolo[5,1-c][1,2,4]triazine 13.     

Binuclear Copper(II) Complexes. N,N′-bis(3-aminopropyl)-oxamidatocopper(II) coordinated as a bidentate ligand

Four new binuclear copper(II) complexes having sub-normal magnetic moment have been synthesized by reaction of N, N′-bis(3-aminopropyl)-oxamidatocopper(II) with another copper(II) compound such as mono- and bis-(2,2′-bipyridine)-copper(II) nitrate, cupric mono-malonate, or cupric chloride. One of them, [Cu₂(APxd)(bipy)₂](NO₃)₂(cf. Fig. 2), was recognized to be a binuclear complex in which each copper(II) ion has a five-coordinated environment. The data from analyses, IR and electronic spectra, magnetic susceptibility measurements, and conductivity measurements were used to establish the structures.     

Consecutive determination of rutin and quercetin by spectrophotometric measurements

The consecutive determination of rutin and quercetin without any pretreatment for separation was examined in methanol solutions by a conventional and a two-wavelength spectrophotometry. Based the tendency of quercetin to form more stable metal complexes compared to rutin, quercetin can be determined through the tin(II) complex formation without interference from rutin. The method was applied to the determination of quercetin in the concentration range of 3.0 × 10^?6 to 2.0 × 10^?5M.Quercetin is apt to be oxidized by oxygen rather than rutin, especially in the presence of copper(II), whereas rutin is not decomposed under such a condition. After removal of quercetin through copper(II)-catalyzed oxidation, rutin ranging in concentration from 2.0 × 10^?6 to 2.0 × 10^?M was determined by the absorbance measurement of rutin-copper(II) complex in slightly alkaline methanol media.Both rutin and quercetin were determined directly by two-wavelength spectrophotometry, without adding any complex forming metals; the lower limit of detection was about 1.0 × 10^?5M. The method was extended to the determination of a smaller amounts of rutin and quercetin using the absorption peaks of their zirconium(IV) complexes, and the determination of both components in the range of 5.0 × 10^?6 to 3.0 × 10^?5M was made with a relative error of within ±4%.     

Structure elucidation of a novel analog of sildenafil detected as an adulterant in a dietary supplement using LC-UV and LC/MS

A sildenafil-related compound was detected in a dietary supplement marketed as an aphrodisiac. The compound was detected during analysis of the dietary supplement using LC-UV and LC/electrospray ionization-MS. The structure of the compound was established using high resolution MS, NMR spectrometry, and X-ray crystal structure analysis. The compound was identified as 5-(5-((3,5-dimethylpiperazin-1-yl)sulfonyl)-2-ethoxyphenyl)-l-methyl-7-((1-methyl-4-nitro-1H-imidazol-5-yl)thio)-3-propyl-1H-pyrazolo[4,3-d] pyrimidine. Based on this structure, the compound was named nitroprodenafil. The dietary supplement was found to contain 90 mg nitroprodenafil/capsule. This article describes the structural characterization of a new sildenafil-related compound. The compound was detected during analysis of a dietary supplement using LC-UV and LC/electrospray ionization (ESI)-MS. The structure was established using high resolution MS (HRMS), NMR spectrometry, and X-ray crystal structure analysis. The structures of methisosildenafil, thiomethisosildenafil, and this new analog, named nitroprodenafil (21), are shown in Figure 1. In the Demizu et al. report, the compound is named mutaprodenafil instead ofnitroprodenafil. Considering the naming right, the authors of this paper think the use of mutaprodenafil is appropriate as the compound name, although nitroprodenafil is used.     

Metabolic profiling of urine and blood plasma in rat models of drug addiction on the basis of morphine,methamphetamine, and cocaine-induced conditioned place preference

The metabolic profiles of urine and blood plasma in drug-addicted rat models based on morphine (MOR), methamphetamine (MA), and cocaine (COC)-induced conditioned place preference (CPP) were investigated. Rewarding effects induced by each drug were assessed by use of the CPP model. A mass spectrometry (MS)-based metabolomics approach was applied to urine and plasma of MOR, MA, and COC-addicted rats. In total, 57 metabolites in plasma and 70 metabolites in urine were identified by gas chromatography–MS. The metabolomics approach revealed that amounts of some metabolites, including tricarboxylic acid cycle intermediates, significantly changed in the urine of MOR-addicted rats. This result indicated that disruption of energy metabolism is deeply relevant to MOR addiction. In addition, 3-hydroxybutyric acid, l-tryptophan, cystine, and n-propylamine levels were significantly changed in the plasma of MOR-addicted rats. Lactose, spermidine, and stearic acid levels were significantly changed in the urine of MA-addicted rats. Threonine, cystine, and spermidine levels were significantly increased in the plasma of COC-addicted rats. In conclusion, differences in the metabolic profiles were suggestive of different biological states of MOR, MA, and COC addiction; these may be attributed to the different actions of the drugs on the brain reward circuitry and the resulting adaptation. In addition, the results showed possibility of predict the extent of MOR addiction by metabolic profiling. This is the first study to apply metabolomics to CPP models of drug addiction, and we demonstrated that metabolomics can be a multilateral approach to investigating the mechanism of drug addiction.     

Syntheses and characterization of μ-Bis{N-(oxopropyl)-glycinamidato}-dicopper(II) and μ-Bis{n-(oxopropyl)-DL-alaninamidato}-dicopper(II)

Two new complexes, [Cu(OP-gld)]₂ and [Cu(OP-alad)]₂ (shown in Fig. 2) with a subnormal magnetic moment have been synthesized and characterized by means of analyses, magnetic susceptibility measurements, IR-, and electronic spectra, and conductivity measurement.