a borítólapra  Súgó epa Copyright 
European chemical bulletinVol. 4., No. 7-9. (2015.)


Classical and Advanced Chemical Sciences

  • Rajni Kant ,
    Ratika Sharma ,
    Vinutha V. Salian ,
    B. K. Sarojini ,
    B. Narayana :

    The title compound C40H26O2 [(2E, 2'E)-3, 3'-(1,3-Phenylene)-bis(1-(anthracene-9-yl)prop-2-en-1-one)] was prepared from the reaction of isophthalaldehyde and 9-acetylanthracene treated with solution of ethanol and sodium hydroxide. It has been crystallized from DMF using slow evaporation method in the triclinic space group P-1 with Z=2 and unit cell parameters, a = 9.8276(8) b = 10.7470(8), c = 14.5606(10) Å, α= 99.833(6), β=104.495(6), γ= 97.371(6)º. The architecture of the crystal structure is determined mainly by three intermolecular interactions [C23-H10…O1, C25-H15…O1, C16-H17…O1], here O1 acts as an acceptor to three different carbon atoms, resulting into the formation of a trifurcated hydrogen bond, forming a graph set motif R22(8) through a pair of C25-H15...O1 interactions. These motifs are further extended through another intermolecular hydrogen bond [C3-H6...O2] forming a ladder like network, extending along the c-axis.

    Keywords: anthracene, single crystal XRD, direct method, intermolecular interactions, hydrogen bonding

  • Shawket J. Jawada ,
    Faris H. Hayder :

    The cloud point extraction (CPE) method has been applied to the extraction and pre-concentration of Mg2+ ions. The extracted solvated species showed a maximum absorbance at λmax = 249 nm. The optimum conditions for extraction of solvated species to CPL are the presence of 0.5 M KNO3 for 50 μg Mg2+ ion in 10 ml aqueous solution with 1×10-4 M of extractant, 2,4-dimethyl-pentan-3-one (2,4-DMP) and heating up to 90 °C for 15 minutes and addition of 0.5 mL of 1 % Triton X–100 as surfactant. The study showed that different extractant have different extraction efficiency, acetophenone showing higher extraction efficiency but ethyl methyl ketone has a lower efficiency. The effect of different salts and variable concentration of nitrate salts on the extraction efficienct has been studied. Determination of Mg2+ in different samples has been studied with a RSD = 0.0074, DL = 1.84×10-5 and Sandel’s sensitivity = 3.58 ×10-9 μg cm-2.

    Keywords: Magnesium; cloud point extraction, solvent extraction, solvation, pre-concentration

  • Alena Voronina ,
    Anna Filippova ,
    Mikhail Razumov ,
    Ilya Kuzmin ,
    Maxim Shepelev ,
    Artur Vashurin ,
    Oleg Golubchikov :

    The influence of solvating power of medium on self-organization of metallophthalocyanines in solution has been studied. It is shown that phthalocyanine macrocycles form H-associates in universal solvation medium. In case of specific solvation the nature of peripheral substitution of phthalocyanine macrocycle plays important role in the formation of ordered structure.

    Keywords: Phthalocyanine; cobalt complexes; aggregates; solvation effect

  • Omar Abderrahim ,
    Benaïssa Esma ,
    Mohamed Amine Didi :

    The aim of this study is to investigate Lewatit TP 214, which is a chelating ion-exchange polymer containing chemically bonded thiourea group, for the sorption of Pb(II) and Cd(II) ions from aqueous solutions. The effects of parameters such as the concentration, pH, contact time, ionic strength and temperature have been investigated. The results showed more affinity of resin towards cadmium than for lead cations. Lewatit TP 214 exhibited a good sorption potential at initial pH values for Pb(II) and Cd(II) at room temperature. The extraction kinetics, for both Pb(II) and Cd(II), is best described by the pseudo second order model. This study showed that the diffusion of moving boundary particles fits well the experimental data (r > 0.99) for the sorption of both Pb(II) and Cd(II) ions. The Langmuir isotherm fits better with the obtained equilibrium data as compared to that with the Freundlich isotherm. The thermodynamic data for the sorption of Pb(II) and Cd(II), on the resin, indicate that the process is endothermic for Pb(II) while it is exothermic for Cd(II). The process showed negative ΔG values, indicating that the sorption of both Pb(II) and Cd(II) ions is spontaneous.

    Keywords: Pb(II), Cd(II), polystyrene thiourea, kinetics, thermodynamics, diffusion

  • G. M. Manahelohe ,
    K. S. Shikhaliev ,
    A. Y. Potapov :

    This study is concerned with the synthesis and characterization of derivatives of 1H-1,2-dithiol-1-thiones and thioamides having the hydroquinoline moiety. 5-Alkyl-8-(carbonothioyl)-4,5-dihydro-4,4-dimethyl-1H-[1,2]dithiolo[3,4-c]quinoline-1-thiones were synthesized by reacting of N-alkyl-2,2,4-trimethyl-1,2-dihydroquinoline-6-carbaldehydes, cyclic secondary amines and excess elemental sulfur (7.33 equivalents) in refluxing DMF. A series of thioamides derivatives containing hydroquinoline fragment were obtained in 56-84% yields by the three-component reaction of N-alkylhydroquinoline-6-carbaldehydes, cyclic secondary amines and 1.33 equivalent of elemental sulfur by refluxing in DMF.

    Keywords: 1H-1,2-dithiol-1-thione; Willgerodt-Kindler reaction; thioamides; hydroquinolinecarbaldehyde

  • Sudam S. Pandule ,
    Suresh U. Shisodia ,
    Mahadeo R. Patil ,
    Vasant V. Chabukswar :

    A simple, highly efficient and economic method for the mono-bromination of number of aromatic amines and phenols using La(NO3)3 .6H2O as a catalyst is explained. The protocol is regioselective, high-yielding and applied at room temperature to a number of aromatic amines and phenols having electron donating or withdrawing substituents.

    Keywords: Regioselectivity; Bromination; Amines; Phenols; Catalysis

  • Suresh Sharma ,
    Goutam Brahmachari ,
    Bubun Banerjee ,
    Rajni Kant ,
    Vivek K. Gupta :

    The title compound, 2-amino-4-isopropyl-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (C16H14N2O3) is synthesized via one-pot multi-component reaction (MCR) at room temperature using commercially available urea as inexpensive and environmentally benign organo catalyst and crystallizes in the triclinic space group P -1 with the unit-cell parameters: a = 7.8231(4), b = 8.0622(4), c = 12.3038(5) Å, α = 99.443(4)o, β = 102.419(4)o, γ = 109.907(4)o and Z = 2. The crystal structure was solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0405 for 2118 observed reflections. The packing of molecules within the unit cell is stabilized by N-H…O and N-H…N type of intermolecular hydrogen interactions. In addition C-H…π and π-π interactions are also observed in the crystal structure.

    Keywords: 2-Amino-4-isopropyl-5-oxo-4,5-dihydropyrano[3,2-C]chromene-3-carbonitrile; X-ray structure; space group; direct methods; π-π interactions

  • Ashok Kumar Yadava ,
    Hardeo Singh Yadav ,
    Rajul Saxena ,
    Devendra Pratap Rao :

    New Schiff base (L), derived from condensation of 1,1’-oxalyldiimidazole with o-phenylenediamine has been prepared. Five new oxovanadium(IV) complexes (one is [VO(L)]SO4 and four [VO(mac)]SO4) have been carried out by using in situ method of preparation where vanadyl ion act as kinetic template for the Schiff bases. The synthesized complexes were characterized by elemental analyses, conductometric measurements, magnetic moments, IR, ESR and electronic spectroscopy. These complexes contain VO2+ group and have square pyramidal geometry wherein Schiff bases act as tetradentate chelating ligands.

    Keywords: Schiff base; 1,1’-oxalyldiimidazole; oxovanadium(IV); chelating legends

  • Theia'a N. Al-Sabha ,
    Nidhal M. S. Mohammed ,
    Payman A. Abdul-Jabar :

    Simple, sensitive and reproducible spectrophotometric method was developed for estimation of oxymetazoline hydrochloride via charge transfer complex formation reaction. The method is based on the reaction of oxymetazoline as n-donor with DDQ reagent as π-acceptor in basic aqueous medium of pH 9.79. The maximum absorption is 421 nm. Beer's law was obeyed in the range 0.4-4.0 μg mL-1 with molar absorptivity 2.5 x 104 L mol-1 cm-1. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.0093 and 0.028 μg mL-1 respectively. The stability constant has been determined and the mechanism of the reactions was proposed. The proposed method was applied to determine the oxymetazoline hydrochloride in dosage form as drop, and the results were statistically compared with official BP method.

    Keywords: Oxymetazoline; 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); spectrophotometry; charge transfer complex

  • Theia'a N. Al-Sabha ,
    Nagham N. Habeeb :

    A simple, sensitive and accurate spectrophotometric method has been developed for the determination of mesalamine in pure and commercial dosage forms. The method is based on the reaction of mesalamine with sodium nitroprusside in the presence of hydroxylamine hydrochloride in alkaline medium to give a highly green colored species which absorb maximally at 703 nm. Beer's law is obeyed in the concentration range of 0.0-30 μg mL-1 with molar absorptivity = 2.0367104 L mol-1 cm-1. The average recovery is 103.0 % and relative standard deviation is less than 1.5 % (n = 6). The proposed method has been applied successfully for determination of mesalamine in commercial pharmaceutical products such as tablet and suppositories. There is no interference from the excipients.

    Keywords: Spectrophotmetry, Sodium nitroprusside, Mesalamine

  • Sakshi Sharma ,
    Goutam Brahmachari ,
    Bubun Banerjee ,
    Rajni Kant ,
    Vivek K. Gupta :

    The title compound 5'-chloro-1H,1"H-[3,3':3',3"-terindol]-2'(1'H)-one is synthesized via one-pot multicomponent reaction (MCR) at room temperature using commercially available sulfamic acid as inexpensive and environmentally benign organo-catalyst. It crystallizes in the monoclinic space group P21/n with the unit-cell parameters: a = 15.3117(15), b = 10.9302(8), c = 16.591(2) Å, 90.00o β = 98.224(10) , γ = 90.00 and Z = 4. The crystal structure was solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0735 for 2539 observed reflections. Both the DMSO solvent molecules take part in the inter- and intramolecular interactions that are responsible for the formation of hydrogen bonded network. Two C-H···π inter-molecular hydrogen bonds are also present in the crystal structure.

    Keywords: Crystal structure; direct methods; hydrogen bond; 5'-chloro-1H,1"H-[3,3':3',3"-terindol]-2'(1'H)-one

  • Ashan Elahi ,
    Rajni Kant :

    Energy calculations have been performed on a series of ten molecules of linear furanocoumarin derivatives to obtain the total stabilization energy i.e. lattice energy of the crystal and also the energy of neighbouring molecular pairs participating in the stabilization of the crystal. The total stabilization energy (lattice energy) lies in the range -16 to -40 kcal mol-1. Analysis of the energetics of the neighbouring molecular pairs in these structures shows the presence of different intermolecular interactions participating in the crystal packing. In addition to the significance of coulombic nature of bifurcated C-H…O hydrogen bonds, the stabilizing role of π…π stacking interactions has been realized in these structures. A careful observation of energetics of different molecular pairs involving C-H…O hydrogen bond reveals that motifs involving C(sp2)-H…O hydrogen bonds are more stabilized than those of C(sp3)-H…O.

    Keywords: Furanocoumarin; lattice energy; intermolecular interactions; PIXEL

  • D. S. Bhagat ,
    M. V. Katariya ,
    R. D. Ingle ,
    V. M. Joshi ,
    M. R. Bachhav ,
    R. N. Udavant ,
    R. P. Pawar :

    An efficient and greener one pot method has been developed for the synthesis of isoindolo[2,1-a]quinazolines using 2-morpholinoethane sulfonic acid as a water soluble green catalyst at ambient temperature and excellent yield of product. The synergetic effect of 2- morpholineethane sulphonic acid and ultrasound irradiation process has been also discussed.

    Keywords: 2-Morpholinoethanesulfonic acid; ultrasound; multi-component reactions; 2-carboxybenzaldehyde; isatoic anhydride; aromatic amines, benzylamine

  • A. Yu. Potapov ,
    K. S. Shikhaliev ,
    A. V. Falaleev :

    This study is concerned with a three-component method of synthesis of new 1,2,3,4-tetrahydro-6Н-pyrimido[1,2-а][1,3,5]triazin-6-ones based on 2-amino-3H-pyrimidine-4-ones, aliphatic amines and formaldehyde. Conditions of reaction were optimized.

    Keywords: 2-Arylamino-3H-pyrimidine-4-ones; three-component reaction; aliphatic amines; 1,2,3,4-tetrahydropyrimido[1,2-a][1,3,5]triazine-6-ones

  • D. Yu. Vandyshev ,
    K. S. Shikhaliev ,
    A. Yu. Potapov :
    Interaction of 1,2-diaminobenzimidazole with Narylimides424-427en [154.59 kB - PDF]EPA-02286-00035-0150

    Substituted 10-amino-2,3,4,10-tetrahydro-4-oxo-N-arylpyrimido[1,2-a]benzimidazole-2-carboxamides are formed by condensation of 1,2- diaminobenzimidazole with N-arylmaleimides in isopropyl alcohol in the presence of catalytic amount of acetic acid.

    Keywords: N-arylmaleimides; 1,2-diaminobenzimidazole; polynucleophiles; 10-amino-2,3,4,10-tetrahydro-4-oxo-N-aryl-pyrimido[1,2-a]benzimidazol-2-carboxyamides

  • Reda M. Fikry ,
    Nabila A. Ismail ,
    Said A. Said ,
    Mohammed E. Hafez :
    Synthesis and reaction of some new benzimidazole derivatives428-431en [101.24 kB - PDF]EPA-02286-00035-0160

    4-Amino-5-(1H-benzimidazol-2-yl)-6-(4-chlorophenyl)pyridine-3-carbonitrile (3) was obtained from reaction of 2-cyanomethyl-1Hbenzimidazole 1 with chlorobenzaldehyde followed by reaction with malononitrile. Reaction of (3) with cyclohexanone, formic acid and hydrazine hydrate afforded tetrahydrobenzonaphthyridine amine, pyrido[4,3-d]pyrimidin-4(3H)one and pyrazolo[4,3-c]pyridine-3-amine, respectively. Heterocyclization of (3) with carbon disulfide and benzoyl isothiocyante gave the corresponding pyrido[3,4- d]pyrimidindithione and thioxopyrido[4,3-d]pyrimidine methanone. While, the reaction of (3) with ethyl cyanoacetate, diethyl malonate and nitrous acid afforded oxo-1,6-naphthyridin-3-carbonitrile, carboxylate and pyrido[4,3-d][1,2,3]triazine, respectively. Dihydroimidazol pyridin-4-amine was obtained from reaction of (3) with ethylendiamine and carbon disulfide. Finally, cyclization of (3) with triethyl orthoformate, in the presence of hydrazine hydrate, afforded pyrido[4,3-d]pyrimidin-3-ylamine.

    Keywords: Benzimidazole, 4-aminopyridine-carbonitrile, pyridopyrimidine, naphthyridine, pyridotriazine

  • Abdelreheem A. Saddik ,
    Khairy M. Hassan ,
    Adel M. Kamal El-Dean ,
    Mohamed S. Abbady :
    Synthesis of new mercaptopyrimidines and thienopyrimidines436-441en [119.87 kB - PDF]EPA-02286-00035-0170

    2-Alkylmercapto- 4-Chloro-6-phenyl-pyrimidine-5-carbonitrile (4a-c) were synthesized and converted into 2-alkylmercapto 4-mercapto-6- phenyl-pyrimidine-5-carbonitriles (7a-c). Compounds (7a-b) were alkylated with halogenated compounds to afford compounds (8a-g). Compounds (8a-g) underwent Thorpe-Ziegler Cyclization to give thienopyrimidines (9a-g). 5-Amino-2-alkylmercapto-4-phenyl-thieno- [2,3-d]pyrimidine-6-carboxamide derivatives (9a-f) underwent cyclization reaction using triethyl orthoformate to afford pyrimidothienopyrimidines (10a-e).

    Keywords: benzaldehyde, thiourea, ethyl cyanoacetate, α-halo carbonyl compounds

  • U. Soni ,
    D. Yajurvedi ,
    S. Vyas ,
    O. Prakash ,
    Pradeep K. Sharma :

    Oxidation of thirty six monosubstituted benzaldehydes by bis[dipyridinesilver(I)] dichromate (BDSD) in dimethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to BDSD. A Michaelis-Menten type kinetics was observed with respect to the reactants. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs= a + b [H+]. The oxidation of [2H]benzaldehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton’s triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraperametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta- substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.

    Keywords: Correlation analysis; chromium(VI); kinetics; mechanism; oxidation; bis[dipyridinesilver(I)] dichromate

Chemical and Biological Aspects of Life

  • N. Kh. Alchujyan ,
    H. A. Movsesyan ,
    A. A. Aghababova ,
    A. G. Guevorkyan ,
    N. H. Movsesyan ,
    H. F. Khachatryan ,
    V. H. Barseghyan ,
    H. L. Hairapetyan ,
    Sahakyan L. S. ,
    L. G. Avanesyan ,
    L. H. Melkonyan ,
    K. A. Barseghyan ,
    G. A. Kevorkian :

    The effectiveness and mechanisms of antitumor activity of non-pathogenic Escherichia coli EM0 strain using mouse model of Ehrlich ascites carcinoma (EAC) is studied. 48 h after inoculating EAC cells, a single noninvasive treatment of the 2-month-old male white mice’s eyes and mouths with live E. coli isolate increased the life span by 75% (P<0.001). Furthermore, a significant decrease in the volume of ascites fluid (66.5 %, P<0.01) was determined, accompanied by down-regulation of EAC-activated lipid peroxidation processes and changes in the L-arginine metabolic profile in leukocytes as early as within 9 days of post-treatment compared to non-treated EACbearing mice. We found EAC-induced stimulation of arginase and nitric oxide synthase (NOS) activity correlated with the levels of their common substrate, L-arginine and products (arginase-derived L-ornithine and NOS-derived NO and L-citrulline) in the cytoplasm and mitochondria of peritoneal and blood leukocytes. The biochemical pattern was differentially modulated by E.coli treatment depending on whether leukocytes were localized in the ascitic fluid or the peripheral blood. E. coli concentrated in the ascitic fluid directly affected the surrounding cells including peritoneal leukocyte in which it decreased the activity of two arginase isoforms and a total NOS in the cytoplasm. Negligible number of E coli at sites remote of tumor suggests its indirect effects particularly via stimulation of LPS-mediated non-specific immune response associated with activation of arginase and NOS in the cytoplasm of blood leukocytes. The data obtained should be taken into account in the further study aimed to use non-pathogenic E. coli strains in the adjuvant therapy of ascites tumors.

    Keywords: arginase; cytoplasm; Ehrlich ascites carcinoma; Escherichia coli; leukocyte; lipid peroxidation; mitochondria; nitric oxide synthase

  • Fatmir Faiku ,
    Arben Haziri ,
    Fatbardh Gashi ,
    Naser Troni ,
    Haxhere Faiku :

    The soil and climatic conditions are conducive for the growth of a lot of medical herbs in Kosovo. Lipids, proteins, minerals and essential oils were quantitatively determined from the Pinus nigra Arnold and Pinus sylvestris growing wild in Germia Park (located in the north-east of Pristina). Total proteins were analyzed, by Kjeldahl method. The total amount of proteins in Pinus nigra Arnold is 7.714 % and in Pinus sylvestris is 4.375 %. Lipids are analyzed by Soxhlet extraction. The total amount of lipids in Pinus nigra Arnold are 7.185 % and in Pinus sylvestris 6.670 %. Essential oils were isolated using steam distillation. The total amount of essential oils in Pinus nigra Arnold are 0.35 % and in Pinus sylvestris 0.32 %. The mineral content was studied and analyzed by flame atomic absorption spectrometry. Six elements, sodium, potassium, calcium, zinc, iron and copper were determined in Pinus nigra Arnold and Pinus sylvestris. The mean levels of sodium, potassium, calcium, zinc, iron and copper are 246 mg kg-1, 1280 mg kg-1, 4260 mg kg-1, 17.2 mg kg-1, 173 mg kg-1, 3.83 mg kg-1 in Pinus nigra Arnold, respectively. The mean levels of sodium, potassium, calcium, zinc, iron and copper are 6.9 mg kg-1, 420 mg kg-1, 1180 mg kg-1, 95 mg kg-1, 840 mg kg-1, 19 mg kg-1 in Pinus sylvestris, respectively. Calcium and potassium are present in large amounts in Pinus nigra Arnold while calcium and iron are present in large amounts in Pinus sylvestris.

    Keywords: Pinus nigra Arnold, Pinus sylvestris, proteins, lipids, minerals, essential oils

  • Yukiko Koshiro ,
    Mel C. Jackson ,
    Chifumi Nagai ,
    Hiroshi Ashihara :

    Changes in concentration (% of dry weight) and content (mg/organ) of sucrose, glucose, fructose and some organic acids in pericarps and seeds of Coffea arabica cv. Mokka, C. arabica cv. Catimor and C. canephora were monitored during the development and ripening of fruits. The coffee fruits were categorized into five stages 1 to 5 which corresponded to small, medium and large sizes of green fruits, ripening (pink) fruits and fully-ripened (red) fruits, respectively. In all samples, the major sugars in young fruits (stage 1) were fructose (~5 % dry weight) and glucose (~3 % dry weight). Significant amounts of sucrose were also found in the later stages of development. The concentration of sucrose in ripened pericarp and seeds (stage 5) in two cultivars of C. arabica (19–25 % of dry weight in pericarp and 8– 18% in seeds) was higher than those in C. canephora (8 % in pericarp and 5 % in seeds). Sucrose was accumulated exclusively in seeds of two cultivars of C. arabica. In contrast, both sucrose and the reducing sugars, fructose and glucose, accumulated in pericarps of all coffee samples and in seeds of C. canephora. The concentration of malic acid, citric acid, lactic acid, oxalic acid and quinic acid changed during development and ripening of fruits. The values of most organic acid fluctuated between 0–1%, except for a transient, high content of quinic acid (>2%) in young fruits. Characteristic accumulation patterns of organic acids were found in different organs; citric acid concentration was high in seeds, but malic acid or oxalic acid was high in pericarps. Possible metabolic routes of metabolites are discussed.

    Keywords: Sucrose, Citric acid, Malic acid, Quinic acid, Seed, Pericarp, Coffea arabica, Coffea canephora

  • Fatmir Faiku ,
    Arben Haziri :

    The soil and climatic conditions are conducive for the growth of a lot of medical herbs in Kosovo. Mentha longifolia (L.) is native to Europe, Central Asia and Australia. Lipids, proteins, minerals and essential oils were quantitatively determined from the Mentha longifolia (L.) growing wild in Germia Park (located in the northeast of Pristina). Total proteins were analyzed, by Kjeldahl method. The total amount of proteins in the Mentha longifolia (L.) is 8.227 %. Lipids are analyzed by Soxhlet extraction. The total amount of lipids in the Mentha longifolia (L.) are 5.804 %. Essential oils were isolated using steam distillation. The total amount of essential oils in the Mentha longifolia (L.) are 0.589 %. The mineral content was studied and analyzed by flame atomic absorption spectrometry. Six elements, sodium, potassium, calcium, zinc, iron and copper were determined in the Mentha longifolia (L.). The mean levels of sodium, potassium, calcium, zinc, iron and copper are 509.7 mg kg-1, 4055 mg kg-1, 9097 mg kg-1, 256.7 mg kg-1, 11841 mg kg-1, 82.83 mg kg-1 in the Mentha longifolia (L.), respectively. Iron and calcium are present in large amounts in the Mentha longifolia (L.). The antioxidant activity of essential oil was evaluated by means of the 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging method. During the analysis of antioxidant activity of the extracts of Mentha longifolia (L) it has been observed that only H2O extract shows strong antioxidant activity than BHT and BHA.

    Keywords: Mentha longifolia (L.), essential oil, proteins, lipids, antioxidant activity, DPPH

Chemical and Biological Aspects of Life

  • Adango Miadonye ,
    Shanshan Lin :

    While the formation of water-in-crude oil (W/O) emulsion is identified to cause serious problems in petroleum industry such as decrease in the efficiency of oil recovery, increase in pumping cost, and pipeline corrosion its treatment has been based mostly on gravity separation by mechanical/chemical technology. As an integral part in the process of oil production and transportation, crude oil demulsification has received attention. In this work, microwave demulsification and the influence of a variety of inorganic salts to the microwave process has been studied. A comparative study on microwave demulsification of heavy oil and light oil has also been conducted. The obtained results showed water separation of 47 % between irradiated and non-irradiated emulsion for heavy crude oil compared to 13 % for light crude oil. The effect of different inorganic salts and the optimum amount of the electrolyte to promote demulsification were also determined.

    Keywords: Crude oil, microwave process, demulsification process, inorganic salts, brine water, oil-water emulsions

Theoretical and Computational Chemistry

  • V. I. Krupyanko :
    An Additional Possibility of Using The Hill Coefficients340-342en [415.25 kB - PDF]EPA-02286-00035-0240

    The possibility of using the Hill coefficients to estimate the first K0 0.5(A1) and the second K0 0.5(B1) constant for the active center of twosubunits of enzymes is considered. The method to calculate K0 0.5(A1) and K0 0.5(B1) constants is discussed.

    Keywords: Hill coefficients, active centers of enzymes