STUDIA CHEMIA - Issue no.1 / 2018 - Table of contents

Heterologous Expression and Purification of Recombinant Crotoxin B, the Phospholipase A2 Subunit of Crotoxin


Crotoxin is a heterodimeric β-neurotoxin isolated from the venom of Crotalus durissus terrificus, consisting of two, non-covalently bound subunits, crotapotin (CA) and crotoxin B (CB). Both subunits present four different isoforms, consequently there are up to 16 different crotoxin complexes, each with different activity levels. The biological activities usually associated with crotoxin include neurotoxicity, myotoxicity and cardiotoxicity, however several other important biochemical and pharmacological effects of crotoxin have been observed, such as the antibacterial, antiviral, antiinflammatory, antitumoral and analgesic activity. In this study we present the production of recombinant crotoxin B (isoform C). Expression of the protein was carried out using E. coli RosettaTM (DE3)pLysS strain, and the obtained protein was separated and purified using Ni2+-affinity chromatography. To the best of our knowledge the developed method represents the first reported method for obtaining the crotoxin B (isoform C) through heterologous expression using an efficient and cost-effective procedure.

Keywords: Crotoxin, neurotoxin, phospholipase A2, heterologous expression

Screening of Bioactive Compounds Synthesized by Microalgae: a Progress Overview on Extraction and Chemical Analysis


Considering the high biodiversity of microalgae and their important impact on economy and ecological balance, new screening techniques are needed for their phenotypic characterization and efficient valorization of bioactive components. This represents one the key purpose of the emerging bioeconomy concept, involving new biorefinery technologies coupled with advanced analytical tools. The article presents an overview of the recent extraction and chemical techniques used to recover, separate and characterize the main bioactive molecules (lipids and fatty acids, carbohydrates, proteins and mycosporine-like amino acids chlorophylls and carotenoid pigments) syntesized by microalgae, considering their interesting applications in food, pharmaceutical and cosmetic industries. Special focuses will be directed towards the cell disintegration and extraction procedures, identification and quantification of main metabolites by advanced analytical techniques.

Keywords: microalgae, bioactive compounds, cell disruption, extraction, spectrometry, chromatography

The Assessment of Fluorophores Advanced Glycation End Products-to-Kynurenine Ratio in Healthy and Diabetic Rats and Humans


In this study, we calculated the ratio of the serum contributions of two highly studied fluorophore products (advanced glycation end products - AGEs and kynurenine - KYN) in the area of nutrition and metabolic diseases including diabetes mellitus (DM), by using a non-invasive, economical and easy-to-perform method. Blood serum spectrofluorimetric analysis was performed both in the case of normoglycemic (n=10) and diabetic rats (n=10), and in the case of non-diabetic (n=14) and type 2 diabetes mellitus (T2DM) patients (n=52). Our results showed a significant increase in the contributions of the two products in diabetic patients and rats compared to the control group. The ratio of the two compounds was positively correlated with serum glucose levels in the case of rats, and with serum triglyceride values in the case of humans. Also, the presence of DM complications in human subjects and the subsequent calculation of ROC curves led to a predictive value of the investigated ratio (AGEs/KYN) for the presence of peripheral diabetic polyneuropathy (PNP). The obtained results suggest a high potential for the investigated ratio to be considered as a new biomarker for the presence of PNP.

Keywords: Advanced glycation end products, Kynurenine, Blood serum, Diabetes Mellitus, Fluorescence Spectroscopy

Variability in Biochemical Composition of Milk Among Three Representative Breeds of Dairy Cows from Romania


Reported here is a comparative analysis of the milk from three representative breeds of dairy cows from Romania – Maramures Brown (Brună de Maramureş), Romanian Spotted (Bălțata Românească) and Black Spotted Romanian (Bălțata cu Negru Românească) - in terms of SDS-PAGE analysis of the protein distribution, total contents of protein, lipids, lactose, dry substance, somatic cell counts, pH and yield of milk. The Maramures Brown displays the highest percentage of proteins and of dry matter, the lowest yield of milk, the highest amounts of α-lactalbumin and β-lactoglobulin (tied with the Spotted Romanian for the latter) and the lowest serum albumin and immunoglobulin. The Black Spotted Romanian shows the highest yield of milk, the highest content of lactose, the lowest content in lipids and protein and dry matter, the highest content of casein and BSA, and the lowest content of α-lactalbumin and immunoglobulin. The Spotted Romanian shows the highest content of lipids, the highest SSC and the highest proportion of lactoferrin. Positive correlations with r values at 0.6-0.8 are found between the relative contents of various components - α vs. β casein, Ig vs. α casein, Ig vs. βLgb, lactoglobulin vs. lactalbumin, β casein and αLac, BSA vs. β casein and αLac, total protein content vs. dry residue, SSC vs. lactoferrin and β casein. A weak negative correlation is seen between the total lipid content and lactose (-0.6).

Keywords: milk, SDS-PAGE, protein, casein, whey

Ester Plasticizers Based on Fatty Acids from Soybean Oil Used in Peliculogen Compositions


In this paper is described the synthesis and characterization of esters based on soybean oil fatty acids and an assessment of their potential use as plasticizers in wood, concrete or metal paints. Esters of fatty acids were obtained in a chemical reactor with microwave heating, using soybean oil fatty acids and n-butanol or isopentanol in acidic conditions.

Keywords: ester, vegetable oil, fatty acids esters, microwave reactor, peliculogen

New Experimental Sulfoaluminate Clinkers from Natural Raw Material Mixtures


The paper presents new different raw materials mixtures which should lead to the theoretical mineralogical compositions of sulfoaluminate belitic (SAB) clinkers. The mixtures, composed of limestone, gypsum, clay, diatomite, basaltic scoria, volcanic tuff and red mud (bauxite ore processing by-product), have been burned at 1220, 1240 and 1260 °C for one hour in an electrical laboratory furnace, then quenched in fresh air. The resulted clinker samples were studied in thin sections under a polarizing petrographic microscope for clinker structure, microtexture and mineralogical association. The mineralogical assemblage assessment by XRD analyses was completed. The sample XRD patterns (processed by Match software and pdf2 database) have been allowed a qualitative and a semiquantitative estimation (external standard method) of the main mineralogical compounds: C2S (belite), C4AF (brownmillerite), CS̅ (anhydrite), C4A3S̅ (sulfoaluminate), proper for sulfoaluminate belitic clinkers. The identified minor and secondary mineral phases were: alkali (Na, K, Na- K) sulfates, natroalunite (NKA6 S̅ H), limeite (C), periclase (M), gehlenite (C2(A1- x,Mx)(AS)). The following abbreviations were used: C= CaO; S = SiO2; A= Al2O3; F= Fe2O3; S̅ = SO3; H = H2O; M= MgO; N(K)= Na2O(K2O).

Keywords: Sulfoaluminate belitic clinker, clinker chemistry, raw materials, transmission polarizing microscopy, XRD analyses

Accumulation of Heavy Metals in Plantago Major Grown in Urban and Post-Industrial Areas


The enrichment and accumulation of heavy metals (Cu, Pb, Zn, Cd, Cr, Ni) in Plantago major leafs was comparatively studied in an urban (Cluj-Napoca) and a post-industrial area (Baia-Mare) from Romania. These two sites were selected for study as in Cluj-Napoca the dominant metal pollution sources are related to traffic, urban runoff, residential heating and municipal landfill, while in Baia-Mare the main pollution sources are the former ore processing activities and the remaining metal rich mining wastes. The average concentrations of Zn and Pb were higher in the soils collected from the postindustrial area, while the Cr and Ni in those from the urban area. The Cu, Cd, Cr and Ni in plantain leafs were comparable in both areas, while Pb and Zn were higher in the post-industrial area. Based on the enrichment factor and the metal accumulation index, plantain was found to be tolerant to high metal contents and moderate accumulator of Cu and Zn.

Keywords: Plantago major, heavy metal, soil, enrichment factor

Study on the Physicochemical and Chemical Parameters of Drinking and Surface Waters from Mine Area at Village Bov, Balkan Mountain, Bulgaria


Water quality is influenced by natural local climate, geology and anthropogenic effects. In the present study, surface waters in hydrographic area, situated in mining region, in the vicinity of abandon copper mine, are characterized and their quality assessed from the view point of the requirements of European Water Frame Directive and Drinking Water Directive. Three sampling campaigns starting at 2012 from 16 sampling sites, in different seasons were performed in order to evaluate both natural, seasonal variations connected with water regimes and anthropogenic pressures. Chemical elements (Al, As, Ba, Cd, Cr, Co, Cu, Fe, Hg, Mn, Ni, Pb, Se, U, V, Zn and lanthanides) and physicochemical parameters (pH, conductivity, hardness, chemical oxygen demand (CODKMnO4); biological oxygen demand (BOD5); dissolved oxygen; dissolved solids; suspended matter; dry residue; chlorides; sulphates; nitrates; phosphates) were measured for characterization and evaluation of different water sources in the region. Conclusions for the further use of waters from this region as tap waters were presented and validated through the determination of much more chemical elements than these required from national legislation

Keywords: surface water, drinking water, chemical element, physicochemical parameter, ICP-MS

A 250-Year Isotopic Proxy Rainfall Record from Southern Botswana


Climate records along aridity gradients where manifestations of climate change are most profound are important for testing climate models. The Kalahari Transect spans such a gradient, but instrumental records of climate parameters are limited in the sparsely populated region. We analysed the δ13C and δ18O record from a Vachellia erioloba (E.Mey) tree from the southern Kalahari Desert in Botswana to explore its potential as a climate proxy archive. Radiocarbon dates show that the record spans the period 1758-2013 CE. Both the δ13C and δ18O records correlate with local rainfall. The isotope proxies show a weak positive correlation with sea-surface temperature reconstruction from the southwestern Indian Ocean, and a stronger correlation with the El Niño Southern Oscillation index. This appears to contradict previous evidence that higher sea-surface temperatures are associated with reduced summer rainfall over the southern African interior. Instead of eastward shifts in the temperate tropical trough synoptic system during elevated southwestern Indian Ocean temperature anomalies, the evidence supports a westwards shift. The result demonstrates the potential of Vachellia erioloba as a climate proxy archive that may yield past climate variability from the arid regions of southern Africa

Keywords: ENSO, drought, Southern Africa, AMS radiocarbon dating, Vachellia erioloba, oxygen isotopes, carbon isotopes.

Assessment of Groundwater Quality and Associated Health Risks in Rural Areas of Sindh (Pakistan)


Groundwater quality has considerable impact on public health, especially in areas where majority of the people rely on groundwater for drinking purpose. In this scenario, investigation of 175 groundwater samples collected from district Jacobabad and Kashmor, Sindh Pakistan was carried out for physicochemical parameters (color, odor, taste, pH, EC, turbidity, alkalinity, hardness, Cl, SO4 -2, NO3 - and TDS), major cations (Na+, K+, Ca+2 and Mg+2), trace elements (F, As, Fe and Zn) and microbiological organisms (total coliform and faecal coliform). Analysis results showed high level of microbial contamination as 66 and 62% sampling sites were laden with total coliform and faecal coliform organisms respectively. On the other hand, chemicals constituents like hardness, Ca, Mg, Na, K, SO4, Cl, and TDS in 54, 72, 21, 47, 25, 73 and 49% water samples respectively were higher than GVs. Other than this, trace elements like F, Zn, As and Fe were also found in high concentration in 11, 04, 22 and 53% water samples respectively. Health risk assessment due to Fe, As and Zn revealed that arsenic HRI>1 in 22 and 13% water samples for children and adults respectively and overall CDIs and HRI were found in the order of As>Zn>Fe whereas, pollution index (Pi) for Fe was significant among all trace elements investigated.

Keywords: Contamination; pollution index; risk assessment; trace metals; groundwater.

Elemental Content and Lead- Strontium Isotope Characterization of Wine


The ICP-MS technique was used to determine elemental composition (Pb, Sr, Cd, Ni, Co, Cu, Ni, Hg, As, Cr) of wines (Muscat Ottonel, Fetească Albă, Fetească Regală, Fetească Neagră, Merlot and Cabernet Sauvignon) produced during three consecutive years (2014-2016) in Dealu Bujorului Vineyard. The determination of 206Pb/207Pb, 208Pb/206Pb, 206Pb/207Pb and 87Sr/86Sr isotopes from wines was performed for establishing reliable markers for wine geographical origin. For all tested wine samples, the toxic metals contents were found in quantities below the limits imposed by legislation. The highest concentration of heavy metals (Cd and Pb) was found in red wine Cabernet Sauvignon [Cd (0.14±0.01 μg/L) (2013)], followed by the same variety of wine from 2012 [Cd (0.14±0.03 μg/L)], in case of Pb the highest concentration was recorded by Merlot [Pb (54.33±1.00 μg/L) (2011)] followed by the same variety of wine but from 2012 [Cd (51.20±1.19 μg/L). Concerning the concentration of the elements in the white wine, it can be noticed that they recorded close concentration as red wine, Muscat Ottonel [Cd (0.12±0.01 μg/L) (2011)], Feteasca Alba [Cd (0.12±0.01 μg/L) (2012)], in case of Pb from white wines the highest concentration was recorded by Feteasca Alba [Pb (52.07±0.50 μg/L) (2012)], Feteasca Regala [Cd (52.29±1.00 μg/L) (2012)]. The highest mean of 87Sr/86Sr isotopic ratio was obtained at Feteasca Neagra variety [0.726±0.004 (0.575%, 2014)] and Muscat Ottonel variety [0.723±0.003 (0.416 % 2016)]. A possible explanation for the higher mean of 87Sr/86Sr isotopic ration for wine can be the mineral consistency of the vineyard soil and its different eco-climatic conditions. 206Pb/207Pb isotopic ratios in the analyzed wine samples indicated traces of pollution originated in automobile emissions. (206Pb/207Pb=1.1000- 1.1400). The lowest mean 208Pb/206Pb and 206Pb/204Pb isotopic ratios was obtained at Muscat Ottonel variety [2.141±0.007 (0.346% 2015) and 17.469±0.016 (0.094 % 2014)]. The results confirm that the elemental profile and 207Pb/206Pb, 208Pb/206Pb, 204Pb/206Pb, 87Sr/86Sr isotope ratio can be used to track the geographical origin of wine, discriminate between wine production regions, and can be used to characterize wine terroirs for forensic purpose.

Keywords: geographical origin, elemental content, 207Pb/206Pb, 208Pb/206Pb, 204Pb/206Pb, 87Sr/86Sr isotope ratio.

Rapid Ultrasound Assisted Reduction of Azo Dyes for Screening Banned Aromatic Amines


The screening of harmful colorants in consumer products is a global concern. Majority of textile and leather exports undergo extensive quality testing, consuming a lot of time and energy. Consequently, improvements in the rate of reduction of standard method for harmful azo dyes, EN 14362-1:2012 (Annex. F), by combining conventional heating with ultrasonication have been explored to adopt a greener approach. Basic dye behavior was investigated by UV-visible spectroscopy, so that more efficient reduction methods could be designed for high-tech instruments of analysis like HPLC with diode array detection (DAD) and GC with mass spectrophotometer (GC-MS). Four dyes were selected, namely Acid red 1 (AR-1), Direct blue 15 (DB-15), Direct red 28 (DR-28), and Direct red 7 (DR- 7) containing one harmful aromatic amine in their structures which make them critical for analyses. Basic observation that absorbance of dyes (having azo chromospheres in their structure) decreases with their reduction to amines was exploited using UV-visible spectroscopic analysis with preselected absorption bands in the visible region from 400 to 700 nm. The dyes were subjected to two types of ultrasound assisted reduction (UAR) methods; less vigorous (experimental method 1) and more vigorous (experimental method 2). All dyes achieved reductions through ultrasonic assistance, higher than the reference method within ten min of time at or before 70 °C except DR-28, according to experimental method 1. According to experimental method 2, DB-15 and DR-7 achieved reductions equivalent to the reference method in 15 min of UAR at 70 °C whereas AR-1 and DR- 28 achieved in 20 min of UAR. Finally, DR-28 was further subjected to experimental method 3, which was simply EN 14362-1:2012 (F) method for colorants, with UAR. At this stage, standard techniques of analysis exploiting HPLC-DAD and GC-MS were used. According to experimental method 3, even 15 min of UAR caused a greater reduction of DR-28 dye as compared to the standard method (BS EN 14362-1, F). Ultrasonication at 70°C reduced the total dye reduction time by 42% and energy consumption by 85%.

Keywords: Azo dyes, Green chemistry, Ultrasound assisted reduction (UAR), Banned aromatic amines

C-C Chemokine Receptor Type 3 Inhibitors: Bioactivity Prediction Using Local Vertex Invariants Based on Thermal Conductivitylayer Matrix


A series of compounds with known inhibitory activity for C-C chemokine receptor type 3 (CCR3) was considered in order to build a predictive model useful in further development of novel CCR3 inhibitors. Model was built using topological descriptors (Cluj indices included) and multiple linear regression. Principal component analysis was applied in order to enhance the model. Errors were taken into consideration and discussed. Finally, vertex invariants based on thermal conductivity layer matrix proved to be a valuable tool in bioactivity prediction of CCR3 inhibitors.

Keywords: Topological descriptors; QSAR; Regeression model; CCR3 inhibitors.

Evaluation of Polycyclic Aromatic Hydrocarbons in Pork Meat Products Obtained in Traditional Systems in Romania


The aim of this study was to determine the polycyclic aromatic hydrocarbons (PAH) levels in the smoked meat products obtained in the traditional system in Romania. The importance of this study resides in the fact that these compounds are known to be carcinogenic and their levels should be strictly monitored so as to ensure the safety of the consumers. Until now, no study was performed in Romania that addresses this issue in the traditional pork meat products. The study was performed on 60 meat products samples (sausages, bacon, ham) taken from a certified traditional meat processing unit but also from retail units that delivered industrially processed meat products. The method used in the detection of the 15 PAHs analysed was HPLC. Our results showed that the highest percent of total PAHs is found in the traditionally obtained smoked bacon and the lowest in industrially produced pork meat sausage. None of the samples examined exceeded the limit imposed by the European legislation for benzo[a]pyrene (BaP), but the smoked bacon revealed higher values for PAH4 than the allowed limit. Following this study we suggest that a more careful attention should be paid to all factors and apply such smoking conditions that result in the lowest possible contamination with PAH in pork meat products obtained in the traditional system in Romania.

Keywords: polycyclic aromatic hydrocarbons, traditional, industrial, smoked, product.

Pulse Flour Based Emulsions – The Effect of Oil Type on Technological and Functional Characteristics


Three different types of whole pulse flours (broad bean, green and red lentils) were used to obtain emulsions and thereafter heat-set gels, and their properties were compared to the soy protein concentrate. The influence of different vegetable oils (sunflower, canola and palm) on emulsions and heat-set gels properties was investigated by considering the antioxidant activity and rheological characteristics. The emulsifying capacity resulted fairly similar in case of all protein sources in combination with sunflower and canola. Slightly higher emulsifying capacity was observed in case of soy-canola oil emulsion compared to soy-sunflower oil emulsion. The palm oil presented limited capacity to form emulsions. Among studied proteins sources, the highest antioxidant capacity was recorded for broad bean flour. DPPH radical scavenging activity of obtained emulsions was influenced by oil type. It was also observed that antioxidant activity was affected by the thermal treatment. Rheological measurements showed no stability for pulse flour based emulsions, samples entering directly into the transition phase towards flowing. The heat-set gels presented linear viscoelastic regions with higher yield point values in comparison to emulsions. The oil used for preparing the emulsions had a significant influence on yield point value both for emulsions and gels.

Keywords: Emulsions, Fatty acids, Natural antioxidants, Rheology, Legumes

Calcium Hydroxyapatite Supported Cobalt Catalysts for Ethanol Steam Reforming: Effect of the Incorporation Method of Active Phase


Cobalt catalysts supported on calcium hydroxyapatite (Ca10(PO4)6(OH)2, HAp) and modified with cerium ions were prepared in two different ways: direct microwave-assisted hydrothermal synthesis or incipient wetness impregnation method and characterized by XRD, TEM, SEM/EDS, FT-IR and Raman spectroscopy, N2 adsorption–desorption, TPD–NH3, TPR–H2 and XPS. The results indicate that Ca2+ ions in the hydroxyapatite lattice are substituted by Co2+ and Ce3+ under hydrothermal conditions while cobalt and cerium species are formed on the HAp surface during support impregnation. Catalytic activity of samples was tested for hydrogen production via ethanol steam reforming (SRE), and it was found that the highest hydrogen yield (over 3,5 mol H2/mol C2H5OH) and the best distribution of products were obtained for the catalyst prepared by the incipient wetness impregnation method. For this catalyst, Co species formed on the HAp surface was easier reducible than Co2+ ions located in the HAp crystal lattice, and surface was characterized by lower acidity.

Keywords: Cobalt Catalysts, Hydroxyapatite, Hydrothermal Synthesis, Ethanol Steam Reforming.

Heat Transfer Characteristics of Nanofluid Flow Around a Rotating Cylinder


The forced convective flow and heat transfer of nanofluids past a rotating cylinder placed in a uniform cross stream is investigated numerically. The computations are carried out at a representative Reynolds number (Re) of 200. The dimensionless cylinder rotation rate (α) is varied between 0 and 6. The range of nanoparticle volume fractions (φ) considered is 0 ≤ φ ≤ 5%. Two-dimensional and unsteady mass continuity, momentum, and energy equations have been discretized using finite volume method. SIMPLE algorithm has been applied for solving the pressure linked equations. The effect of rotation rates (α) on fluid flow and heat transfer were investigated numerically. In addition, time-averaged (lift and drag coefficients and Nusselt number) results were obtained and compared with the literature data. A good agreement was obtained for both the local and averaged values.

Keywords: unsteady flow, nanofluid, volume fraction, Reynolds number, finite volume, circular cylinder.