Bulgarian Chemical Communications, Volume 50, Number 3, 2018
 
Contents:
   
1

Synthesis, characterization and antioxidant measurements of selenium (IV) complexes with some amino acids - binuclear complexes
Original Research Article
Pages 351 – 362
A. M. Naglah, A. S. Al-Wasidi, N. M. Al-Jafshar, J. S. Al-Otifi, M. S. Refat, R. F. Hassan, W. N. Hozzein
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Abstract
A series of selenium(IV) complexes of asparagine (Asn), proline (Pro), glutamine (Gln), methionine (Met) and cysteine (Cys) amino acids were prepared and well characterized based the (elemental analyses, molar conductance measurement), various spectral studies (IR, Raman, UV-Vis, 1H-NMR and mass) and thermo gravimetric analyses (TG/DTG). The X-ray diffraction studies were carried out using PANalytical X-ray diffractometer, surface homogeneity of the respected samples was investigated using Quanta FEG 250 scanning electron microscope (SEM) and the chemical compositions of these samples have been studied using energy dispersive X-ray analyses. All the selenium (IV) complexes (I-V) are of [Se+4(AA1)2Cl2] type, where AA = (Asn, Pro, Gln, Met and Cys) act as monobasic bidentate ligands in the synthesized complexes. Mass fragments of the [Se (Cys)2(Cl)2] (V) suggest monomeric statement. The speculated geometries of the 1:2 complexes were octahedral configuration with two chlorines and two bidentate ligands occupying the corners of the octahedral complexes. In selenium–Asn, Pro, Gln, and Met complexes both amino and carboxylate groups are involved in coordination with metal, but, Cys coordinates through its sulfhydryl and carboxylate groups. The free radical scavenging activity of newly synthesized selenium (IV) complexes was determined at the concentration of 10, 20 and 30 ppm by means of the interaction with free radical 1,1diphenyl-2-picrylhydrazyl (DPPH) in stable form. All these complexes have a bullish antioxidant activity.

   
2

Identification of volatile compounds from maize aerial parts infested by Chilo partellus (swine hoe) using GC-MS analysis
Original Research Article
Pages 363 – 367
D. Pedda Kasim, P. Suneetha, M. S. R. Krishna, B. Dinesh, R. Sri Deepthi, U. Lakshmi Sahitya
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Abstract
Zea mays is one of the most important stable foods in Asian and African countries and is the second-largest cultivated and highest-yielding crop in India. Lepidopteron stem borer Chilo partellus is a dangerous insect pest in maize. The stem borer makes holes on the stem and leaves and enters inside the stem for feeding. The plant was therefore investigated for its bioactive components. The present study was carried out to identify the volatile compounds present in the n-hexane extract of Zea mays by GC-MS analysis. Total 30 compounds were identified in both infected and uninfected samples. Among the 30 compounds butylated hydroxytoluene, n-hexadecanoic acid and 9,12,15-octadecatrienoic acid, (Z,Z,Z)- were identified as three common major components. Differences in their concentrations reveal their role in plant-insect interactions.

   
3

Antioxidant potential, total phenolic and flavonoid contents of three culinary medicinal plant species of Lesser Hamalya, Pakistan
Original Research Article
Pages 368 – 373
M. Ishaque, Y. Bibi1, A. Qayyum, M. Khalid Rafiq, M. Arshad, S. M. Saqlan Naqvi, S. Nisa, M. A. Jenks
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Abstract
It is well known that oxidative stress due to free radicals can lead to many human illnesses, like cancer. Antioxidants are the agents which scavenge these free radicals and protect the biological system. Food of plant origin is an essential source of reliable antioxidants. These plant-derived antioxidants belong to many biochemical categories but most are phenolics or flavonoids. The Galyat region of Pakistan is rich in plant biodiversity, and local inhabitants frequently use medicinal plants to treat common ailments. Three of these common regional medicinal plants (Dryopteris ramosa, Quercus leucotricophora and Arisaema flavum) were selected and their free radical scavenging potential was investigated using DPPH assay. The crude extract of D. ramosa exhibited the maximum free radical scavenging potential (93.8 ± 0.2 %) while A. flavum (56.4 ± 0.4 %) showed the lowest radical scavenging potential at 250 µg/ml. A low SC50 value of the crude extract of D. ramosa (88.9 ± 0.4 µg/ml) confirmed the relatively high antioxidant potential of this plant species. Among the polarity-based fractions obtained from crude extract of D. ramosa, the ethyl acetate soluble fraction showed maximum free radical scavenging potential. The D. ramosa contained higher amounts of total phenolic and flavonoid compounds than Quercus and Arisaema species. A significant Pearson correlation at the 0.01 level (2 tailed) was also noticed between SC50 and total phenolic contents of all extracts. A significant difference in percentage scavenging activities of the various extracts was observed. The ethyl acetate soluble phase of D. ramosa may prove to be an especially useful source of natural antioxidants for a variety of medicinal uses. Further studies are in progress.

   
4

Study of phytochemical changes, enzymatic and antioxidant activity of two halophyte plants: Salsola dendroides Pall and Limonium reniforme (Girard) Lincz in different seasons
Original Research Article
Pages 374 – 382
S. Bakhshi, H. Abbaspour, S. Saeidisar
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Abstract
In order to study phytochemical changes, enzymatic and antioxidant activity of Salsola dendroides Pall. and Limonium reniforme (Girard) Lincz halophytes, leaf and root samples of these plants were collected from Incheh Borun region in northern Gorgan, Iran, in three seasons (spring in May, summer in August, and autumn in November) in four iterations. The results showed that soil salinity level increased in autumn and significantly increased enzyme activities and antioxidant activities in shoots and roots of both species in most cases. Phytochemical studies showed that phenol content significantly increased in shoot and root of Salsola dendroides in summer and autumn and in Limonium reniforme in summer, compared to theother two seasons. Flavonoid content also significantly changed with seasonal variation. The highest flavonoid accumulation was observed in shoots and roots of the plants in summer; most of these changes were related to activation of physiological and biochemical processes which allow the plants to adapt to salinity conditions.

   
5

Evaluation of the plasma jet effects on the Citrinin and Ochratoxin A producing species of the genus Penicillium
Original Research Article
Pages 383 – 392
N. Vaseghi, M. Bayat, A. Ch. Nosrati, M. Ghorannevis, S. Hashemi
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Abstract
Mycotoxins are small toxic molecules produced by a variety of microorganisms. They are often made of several secondary metabolites and often have a variety of chemical functions and structures. Citrinin and Ochratoxin A produced by different species of Penicillium contaminate various types of foods. Today, the cold atmospheric pressure plasma method has potential for mycotoxin detoxification. In this study, cold atmospheric pressure plasma (CAPP) operating parameters were investigated and optimized to increase the effect on Citrinin and Ochratoxin A in wheat, oat, corn and rice. In this study, the output of power supply first was set to 50 kV, 100 watts and the electron frequency of 30 kHz (optimum conditions for stable and effective plasma) to perform the tests. Then, the effect of cold atmospheric plasma jet (argon) on the gas flow establishment (gas rate 6 6 l/min) for 30, 60 and 360 sec was investigated. The results showed that CAPP method effectively reduces the pure mycotoxins. Overall, there are more than 40% and 50% reduction in the mean initial concentrations of Ochratoxin A and Citrinin, when plasma-treated at 100 W powers. The degree of destruction of various mycotoxins varies according to their structure. It was also shown that the presence of a combination of mycotoxins in foods reduces the plasma's effect but does not prevent their destruction. Finally, in this study, Citrinin and Ochratoxin A were successfully detoxified on all specimens. In addition to mycotoxin detoxification, the CAPP method is neutral in terms of biologic effects and has least negative effects on the nutrients compared to the conventional methods of disinfection of food products.

   
6

Impact of 50 Hz magnetic field on the content of polyphenolic compounds from blackberries
Original Research Article
Pages 393 – 397
M. Răcuciu, S. Oancea
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Abstract
Blackberries are fruits abundant in bioactive compounds which may be extracted from the matrix by several strategies. Different physical or (bio)chemical pre-treatment of samples might favour the extraction of specific compounds. Little is known about the magnetic field influence on anthocyanins and phenolics extraction, which determined the purpose of this work. Fresh wild and cultivated blackberries were exposed to homogenous 50 Hz frequency magnetic field of 3 mT for up to 12 h. The results showed a significant increase of total anthocyanins and antioxidant activity of all samples exposed up to six hours, compared to control sample. Longer exposure time to magnetic field determined a decrease of total anthocyanins content of wild blackberries. The recovery of high amounts of valuable bioactive compounds using the investigated non-thermal strategy renders the technique useful for applications in food, pharmaceutical or cosmetic industry.

   
7

Voltammetric and theoretical study of the interaction of ceftriaxone with phenylalanine
Original Research Article
Pages 398 – 404
H. S. Sayiner, T. Bakir, F. Kandemirli
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Abstract
The interaction between ceftriaxone and phenylalanine (PA) was investigated by cyclic voltammetry and quantum chemical study using DFT (density functional theory) method. The study was carried out in phosphate buffer solution (PBS) at pH 7.0 (which was also used as the supporting electrolyte) by directly dissolving it in twice distilled water. The voltammetric study of ceftriaxone showed well expressed redox peaks at 0.090 V on a GCE in phosphate buffer of pH 7.0 at 50 mVs-1. The cathodic peak currents were linear with different scan rates from 25 to 275 mVs-1 and the correlation coefficient was found to be 0.971 9 and 0.9592 for ceftriaxone and ceftriaxone-PA systems, respectively in the potential range of 0.8-(-0.2) V. The electron transfer rate constant (ks) was calculated for the reduction of ceftriaxone and ceftriaxone-PA interactions as 2.031 and 4.831 s-1, respectively. After the addition of PA to the ceftriaxone solution, the redox binding constant was obtained as K = 1.32×103 M–1 for ceftriaxone-PA interaction, and quantum chemical calculations were performed for ceftriaxone and ceftriaxone-PA complex by the B3LYP method.

   
8

Characterization and drug release from extended-release matrix pellets with montelukast sodium
Original Research Article
Pages 405 – 410
T. M. Popova, St. A. Ivanova, M. V. Dimitrov
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Abstract
The undisputable benefits of pellets, associated with improved bioavailability, make them ideal for presenting in extended-release formulations. Unfortunately, despite the many advantages of wet extrusion and spheronization, extended release is difficult to be achieved, even with commonly used release modifying agents like cellulose derivates, polyethylene oxides, sodium alginate, etc. In order to sort out this problem, we included ethanol in the kneading liquid and investigated its influence on the properties of ethylcellulose (EC) pellets and the release behaviour of montelukast sodium. Differential scanning calorimetry of EC showed increase in heat capacity, associated with increased amount of ethanol, which proved that ethanol changes the thermo-mechanical properties of EC. Moreover, evaporation of ethanol during spheronization caused partial melting and dissolution of EC provoking agglomeration, rounding and smoothing, which reflected in the formation of a hydrophobic film around the particle. As a result, the increase in ethanol concentration in the kneading liquid led to obtaining pellets with narrower particle size distribution, higher dimensions, improved sphericity, flatter surface, longer mean dissolution time (MDT) and slower release of montelukast sodium.

   
9

X-ray photoelectron spectroscopy investigations of lignocellulosic materials
Original Research Article
Pages 411 – 416
I. A. Avramova, T. Hr. Radoykova, I. V. Valchev, D. R. Mehandjiev
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Abstract
Hydrolyzed plant biomass from willow, paulownia and straw was studied by using XPS and IR spectroscopy method in order to understand in depth their chemical composition and the nature of the functional groups on their surfaces. The surface concentration and the presence or absence of some functional groups and their amount on the surface of these materials were studied by the XPS method. The calculated O/C ratio shows that the surface of lignin, paulownia and willow samples was lignin rich, while the surface of straw sample was cellulose rich.

   
10

The effect of iron and manganese oxyhydroxide soil fraction on the occurence of Cr(VI)
Original Research Article
Pages 417 – 422
Ts. Voyslavov, S. Tsakovski, V. Simeonov, S. Arpadjan
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Abstract
The objective of the present paper was to study the effect of soil natural oxidants (Fe/Mn oxides) on the occurrence of Cr(VI) in soil in order to better understand and predict the fate, mobility and toxicity of chromium in the environment. Thirty five surface soil samples were examined for Cr(VI) content in their aqueous and alkaline leachates. The reducible iron and manganese oxides in soils, that could promote the oxidation of Cr(III), were extracted using acidified hydroxylamine hydrochloride solution (BCR procedure). Liquid phase extraction was used for redox speciation of Cr. The results obtained indicated that the Cr(III) oxidation in soils occurs via interactions with iron and manganese oxides. Cr(VI) was the predominant form in aqueous leachates (44–145 μg kg-1 Cr). For the main part of the samples the dissolved alkaline Cr(VI) presented 80 – 89 % of the total soil chromium dissolved in 0.1 mol l-1 NaOH.

   
11

Transformation from  - to β- phase in vinylidene fluoride–hexafluoropropylene copolymer nanocomposites prepared by co-precipitation method
Original Research Article
Pages 423 – 428
L. H. Borisova, D. S. Kiryakova, A. N. Atanassov
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Abstract
Nanocomposite materials on the basis of vinylidene fluoride–hexafluoro-propylene copolymer with Cloisite15A were obtained by a co-precipitation method from dimethylsulfoxide solution. The addition of organically modified nanoclay was found to facilitate the transformation of the polymer crystals from α- to β- phase. The amount of β- phase calculated for the materials containing 6.0 mass % of modified nanoclay was more than 95%. At lower Cloisite15A content, the β- phase also increased compared to that in the initial copolymer and was in the range 47–82%. The increase of the tensile strength and elongation at break of the nanocomposites was higher at lower content of nanoclay Cloisite15A (38–39 MPa and 820–850% at 0.75–1.0 mass %, respectively). The reinforcing effect was lower for the nanocomposites with higher clay content owing to some clay platelets being partially exfoliated and stacked. This was confirmed by transmission electron micrographic observations of the nanomaterials obtained.

   
12

Sol-gel hydrothermal preparation of Bi4Ti3O12 ceramic
Original Research Article
Pages 429 – 432
M. Afqir, A. Tachafine, D. Fasquelle, M. Elaatmani, J-C. Carru, A. Zegzouti, M. Daoud
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Abstract
This manuscript reports a modified method of preparation of Bi4Ti3O12 ceramic powder by a sol-gel approach, followed by hydrothermal treatment of the obtained gel. Bismuth acetate and titanium isopropoxide were used as metallic sources to prepare the precursor gel, and it was successfully converted into bismuth-titanium oxide by hydrothermal treatment at 400 °C and 600 °C for 24 h. Multiple characterizations, namely XRD, FTIR, SEM measurements were used to validate the structural features.

   
13

A metal-organic framework of Co(II): synthesis and supercapacitive properties
Original Research Article
Pages 433 -436
H. L. Bai, F. L. Meng, Y. Fan, P. Zhang
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Abstract
A metal-organic framework based on pytpy and H4abtc as secondary ligands, namely Co2(pytpy)(abtc)2 was solvothermally synthesized and structurally characterized. The supercapacitive behavior of MOFs was determined. There are reduction and oxidation peaks when cyclic voltammetry is performed at different scan rates, which shows typical faradic redox characteristics. The specific capacitances slowly decrease along with the increase in scan rates, which signifies that the material has a good high-rate capability. The results show that the loss of specific capacitance of Co-MOF is not remarkable and it has an excellent cycle life after 1000 cycles test.

   
14

Promotional effect of Au on γ-Al2O3 supported cobalt based catalyst for total oxidation of methane
Original Research Article
Pages 437 – 444
M. Kumar, G. Rattan, R. Prasad
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Abstract
Effect of gold loading (within the range of 4 mass % - 16 mass %) on the behavior of the catalyst (Co/γ-Al2O3) for CH4 oxidation is studied. Gold promoted CoOx/γ-Al2O3 catalysts were prepared via deposition precipitation method and calcined at 550oC. A significant improvement in activity was observed (T100%=380 oC) toward CH4 oxidation with increase in gold loading, though a plateau was reached at ca. 13.45 wt. % Au content. The catalytic activity is studied on a fixed catalyst weight (500 mg) in an air flow containing 1 % of CH4 introduced to the reactor at a total feed rate of 150 mL/min. The catalyst characterization is done using XRD, TGA/DSC and SEM. The best catalysts according to the catalytic activity obtained are as follows: Au (13.45>10.44>16.27>07.21>04.06>0 wt. %)-CoOx/γ-Al2O3. It is found that the catalyst containing 13.45 wt. % of Au loaded on 18 wt. % Co/γ-Al2O3 is the most active catalyst as it decreases the temperature (T100%=380 oC) by 110oC required for methane oxidation in comparison to the catalyst that does not contain gold, i.e., 18wt.%Co/γ-Al2O3 (T100%=490 oC).

   
15

Synthesis and spectral properties of new piperazine derivatives and a structural study
Original Research Article
Pages 445 – 451
Z. Gokmen, N. G. Deniz, M. E. Onan, C. Sayil
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Abstract
In this study, new piperazine derivatives were synthesized by the reactions of S-substituted-3-nitro-1,3-butadienes with some piperazine derivatives: (1-(2-furoyl)-, 1-(4-fluorobenzyl)-, 1-(3-fluorophenyl)- and 1-(1-tetrahydro-2furyl)piperazine) in CHCl3 at room temperature. The structures of the new compounds were characterized by micro analysis, FT-IR, MS spectrometry, 1H- and 13C-NMR. The crystal structure analysis was performed on the synthesized compound 5d by using the X-ray diffraction method. The compound 5d crystallizes in the monoclinic space group P21/c with a = 12.5503(2) Å, b = 11.2039(2) Å, c = 14.1007(4) Å, Z = 4. The structure was solved by direct methods (SIR92) and refined to the residual index R1 = 0.031.

   
16

Molecular modeling of galanthamine derivatives comprising peptide moiety
Original Research Article
Pages 452 – 458
Zh. Velkov, D. Tsekova, V. Karadjova, L. Vezenkov
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Abstract
Using parametrical and semi-empirical quantum-chemical methods, three important descriptors of a series of peptides, linked to the molecule of galanthamine, were calculated. The studied compounds are planned as drugs for the prevention and treatment of Alzheimer’s disease. The descriptors: polarizability, hydration energy and log P, undoubtedly have a bearing on the ability of the compounds to form strong enzyme-inhibitory complexes. Optimal geometries of the investigated peptides, as well as the intramolecular hydrogen bonds that define their structure have been found. Suggestions for the most reliable compounds have been made.

   
17

Newly characterized butyrate producing Clostridium sp. strain 4a1, isolated from chickpea beans (Cicer arietinum L.)
Original Research Article
Pages 459 – 466
S.P. Hristoskova, L.D. Yocheva, D.S. Yankov, S.T. Danova
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Abstract
Butyric acid is a valuable chemical with wide application in various industries. The interest in its biotechnological production is revived in view to the application in the production of alternative fuels from biomass feedstocks. Microorganisms of genus Clostridium are well known as producers of butyric acid. Clostridium species was found to dominate the system in the spontaneous chickpea fermentation. In the present study a Clostridium sp. strain 4a1 from chickpea beans fermentation was selected as a good producer of butyric acid. Some process parameters as initial pH of the medium (7.5), temperature (37 oC), medium composition and glucose concentration (20 g/l) were determined. The strain was identified as Clostridium beijerinskii (97% similarity) on the basis of classical and modern polyphasic taxonomy methods.

   
18

Determination of the drying characteristics of cherry laurel (Laurocerasus officinalis Roem.) puree in a freeze-dryer
Original Research Article
Pages 467 – 477
M. Talih, S.N. Dirim
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Abstract
This study aims at the determination of the effect of thickness on the freeze drying behavior of cherry laurel (Laurocerasus officinalis Roem.) puree, together with the determination of the physical, chemical, and powder properties of the obtained powders and the calculation of the energy efficiency of the drying process. The samples were dried at 3, 5, and 7 mm thicknesses. Among the twelve thin-layer drying models used, the Page (3 and 5 mm) and Logarithmic models (7 mm) were found to satisfactorily describe the drying behavior. The drying times were 8, 10, and 11 h with increasing the moisture extraction rate (MER) and specific moisture extraction rate (SMER), and decreasing specific energy consumption (SEC) values for the increasing thicknesses. The effective moisture diffusivity (Deff) values were between 4.70-7.78E-08 m2/s. The average total phenolic compounds and the vitamin C content values were 710 mg GAE/100g (db) and 23 mg/100g (db)), respectively. The bulk density values were between 99.75 and 113.88 kg/m3, and the flowability and cohesiveness values were at fair-bad, and intermediate-high levels, respectively.

   
19

Edge harmonic index of carbon nanocones and an algorithm
Original Research Article
Pages 478 – 483
E. Aslan, Ö. K. Kürkçü
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Abstract
Edge harmonic index He(G) of the (chemical) graph G is based on the end-vertex degrees of edges of the line graph L(G). In this paper, the generalized formula and an algorithm (pseudocode) are given for edge harmonic index. The aim of this paper is to develop edge harmonic index for generalized carbon nanocones.

   
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