Spectrophotometric study of starch-triiodide system

Škrob je polisaharid pohranjen u biljkama kao rezervna hrana. Po kemijskom sastavu on je smjesa dvaju polimera D-glukoze, amiloze i amilopektina. Kada se otopini škroba doda otopina joda u kalijevom jodidu (otopina trijodida I3- ili Lugolova otopina) nastaje intenzivno modro ili, rjeđe, smeđe obojenje. To obojenje posljedica je nastajanja kompleksa škroba i trijodidnog iona. Koncentracija kompleksa, a samim time i koncentracija škroba može se odrediti spektrofotometrijski mjerenjem apsorbancije danog uzorka. Omjer amiloze i amilopektina varira ovisno o vrsti škroba. Kompleks s trijodidom čine obje komponente škroba, amiloza tvori jaki tamnoplavi, a amilopektin slabi smeđi kompleks. U istraživanju je pokazano kako se apsorpcijski spektri amiloza – trijodid kompleksa mogu uzeti kao parametar za određivanje botaničkog porijekla škroba. Uočene su razlike između različitih vrsta škroba u samom intenzitetu obojenja pri nastanku kompleksa, apsorpcijskom maksimumu te pomaku apsorpcijskog maksimuma u odnosu na reprezentativni uzorak.Starch is a polysaccharide stored in plants as a food reserve. According to its chemical composition it is a mixture of two D-glucose polymers, amylose and amylopectin. When a solution of iodine in potassium iodide (triiodide solution I3- or Lugol solution) is added to a starch solution, intensive dark blue or, rarely, brown coloration appears. This coloration is a result of yielded starch-triiodide complex. Concentration of this complex and thus the concentration of starch can be determined spectrophotometricaly by measuring the absorbance of the given sample. Volume fraction of amylose and amylopectin varies depending on the starch type. Both starch components yield complex with triiodide, amylose yields strong dark blue and amylopectin weak brown complex. Therefore the absorption spectra of amylose-triiodide complex can be taken as a parameter for determination of botanical origin of starch, as presented in this research. Noted differences between various starch types are in the intensity of coloration due to complex formation, maximum wavelength of absorbance and the shift of maximum wavelength of absorbance when compared to representative sample

Spectrophotometric study of starch-triiodide system

Škrob je polisaharid pohranjen u biljkama kao rezervna hrana. Po kemijskom sastavu on je smjesa dvaju polimera D-glukoze, amiloze i amilopektina. Kada se otopini škroba doda otopina joda u kalijevom jodidu (otopina trijodida I3- ili Lugolova otopina) nastaje intenzivno modro ili, rjeđe, smeđe obojenje. To obojenje posljedica je nastajanja kompleksa škroba i trijodidnog iona. Koncentracija kompleksa, a samim time i koncentracija škroba može se odrediti spektrofotometrijski mjerenjem apsorbancije danog uzorka. Omjer amiloze i amilopektina varira ovisno o vrsti škroba. Kompleks s trijodidom čine obje komponente škroba, amiloza tvori jaki tamnoplavi, a amilopektin slabi smeđi kompleks. U istraživanju je pokazano kako se apsorpcijski spektri amiloza – trijodid kompleksa mogu uzeti kao parametar za određivanje botaničkog porijekla škroba. Uočene su razlike između različitih vrsta škroba u samom intenzitetu obojenja pri nastanku kompleksa, apsorpcijskom maksimumu te pomaku apsorpcijskog maksimuma u odnosu na reprezentativni uzorak.Starch is a polysaccharide stored in plants as a food reserve. According to its chemical composition it is a mixture of two D-glucose polymers, amylose and amylopectin. When a solution of iodine in potassium iodide (triiodide solution I3- or Lugol solution) is added to a starch solution, intensive dark blue or, rarely, brown coloration appears. This coloration is a result of yielded starch-triiodide complex. Concentration of this complex and thus the concentration of starch can be determined spectrophotometricaly by measuring the absorbance of the given sample. Volume fraction of amylose and amylopectin varies depending on the starch type. Both starch components yield complex with triiodide, amylose yields strong dark blue and amylopectin weak brown complex. Therefore the absorption spectra of amylose-triiodide complex can be taken as a parameter for determination of botanical origin of starch, as presented in this research. Noted differences between various starch types are in the intensity of coloration due to complex formation, maximum wavelength of absorbance and the shift of maximum wavelength of absorbance when compared to representative sample

Development of a Direct Potentiometric Method for the Determination of Amylase Activity in Barley Malt

Slad je produkt žitarica, najčešće ječma, koji se koristi u pićima i hrani kao podloga za fermentaciju te za dodavanje okusa. Dobiva se klijanjem ječma u kontroliranim uvjetima što omogućava sintezu enzima amilaza, koje embrio biljke koristi za razgradnju škroba. Amilaze su enzimi koji kataliziraju hidrolizu škroba na jednostavnije ugljikohidrate. U ječmu se nalaze dvije vrste amilaza, alfa i beta amilaze, koje se razlikuju po načinu razgradnje škroba. Aktivnost alfa amilaze u sladu ključni je parametar kvalitete za žitarice i brašno u prehrambenoj industriji, posebice u proizvodnji piva i fermentaciji. Također, različite koncentracije alfa amilaze koriste se za modifikaciju svojstava tijesta što uvelike utječe na kvalitetu pečenih proizvoda. U ovom je radu predložena elektrokemijska metoda za određivanje aktivnosti amilaza u sladu. Metoda je temeljena na direktnom potenciometrijskom mjerenju koncentracije trijodidnih iona oslobođenih iz škrob-trijodid kompleksa nakon razgradnje škroba pomoću amilaza iz slada. Kao detektor trijodidnih iona predložena je platinska redoks elektroda. U odnosu na druge dostupne metode, ovaj princip određivanja je jednostavan, brz, jeftin i ne zahtjeva specifične reagense i aparaturu. Rad također sadrži i metodički dio s prijedlogom pripreme za nastavni sat kemije u osnovnoj školi, uključujući i radne listiće s pokusima na temu enzimi.Malt is a grain product, mostly barley, used in beverages and foods as a basis for fermentation and to add flavour. The malt is obtained in barley grain germinating process under controlled conditions that enables the synthesis of amylase enzymes which are used later by plant embryo in order to breakdown starch molecules. Amylases are enzymes that catalyze hydrolysis of starch into smaller carbohydrate molecules. Two main subtypes of amylases can be found in barley malt, alpha and beta, that differ in the way they breakdown the starch molecules. The level of alpha-amylase in malt is a key quality parameter for grains and flour in food industry, mainly in beer production and fermentation. Furthermore, variable concentrations of alpha-amylase are used to modify dough properties, thus influencing the quality of the baked products. The proposed electrochemical method in this paper is based on direct potentiometric determination of levels of triiodide ion released from the starch–triiodide complex after starch degradation by barley malt amylases. A platinum redox electrode is proposed as a detector of triiodide ions. When compared to other available methods, this principle is simple, rapid, inexpensive and doesn't require specific reagents and apparatus. In the teaching part of the thesis a preparation lecture on enzymes for the elementary school chemistry class is proposed. The lecture includes some relevant experiments, questionnaires and handouts

Biosenzori za praćenje teških metala i toksičnih spojeva u okolišu

Praćenje zagađenja okoliša bitan je zadatak u njegovom očuvanju, a pojednostavljenje metodologije za praćenje polutanata imperativ. Teški metali i različiti toksični spojevi posebno su opasni jer se tijekom vremena akumuliraju u biljkama i životinjama. Iz tog su razloga razvijene različite metode pomoću kojih se određuje njihova koncentracija u okolišu. Biosenzori danas predstavljaju brzo i pouzdano rješenje za praćenje zagađenja okoliša uzrokovanog različitim toksičnim spojevima i metalima. Minijaturizacija senzora omogućila je in situ mjerenja, čime se isključuju dugotrajna i ponekad skupa mjerenja u laboratorijima. U radu je prikazan kratak pregled nekih biosenzora te njihova primjena u detekciji i praćenju teških metala i toksičnih spojeva u okolišu

Application of Spectrophotometric Fingerprint in Cluster Analysis for Starch Origin Determination

Botaničko podrijetlo škroba je od velike važnosti za primjenu u industriji i proizvodnji hrane jer može bitno utjecati na svojstva krajnjeg proizvoda. Trenutno dostupne mikroskopske metode za određivanje podrijetla škroba su dugotrajne. Škrob se sastoji od amiloze i amilopektina, čiji omjer ovisi o njegovom botaničkom podrijetlu. Trijodidni ioni se obično vežu za amilozu i amilopektin, a njihovo vezivanje ovisi o podrijetlu škroba. U ovom je istraživanju mjeren apsorpcijski spektar kompleksa škrob-trijodid različitih vrsta, kao što su pšenica, krumpir, kukuruz, raž, ječam, riža, tapioka i škrob nepoznatog podrijetla, te različitih sorata iste vrste. Svaki je uzorak škroba imao specifične parametre: maksimalnu valnu duljinu pika za kompleks škrob-trijodid (λmax/nm), maksimalnu promjenu apsorbancije pri λmax (ΔA) i pomak λmax prema uzorku škroba nepoznatog botaničkog podrijetla. Vidljivi je dio apsorpcijskog spektra (500-800 nm) za svaki uzorak škroba dao jedinstveni otisak, koji je zatim obrađen klaster analizom. Tom su analizom podaci razdvojeni u dva klastera, jedan klaster žitarica i drugi klaster krumpira, tapioke i riže. Unutar klastera škrobova žitarica u podklastere su se izrazito razdvojili škrobovi pšenice, ječma i raži od kukuruznih škrobova. Podaci o sortama dobro su se grupirali unutar istog podklastera. Predložena metoda, koja kombinira klaster analizu i podatke dobivene mjerenjem apsorbancije vidljivog dijela spektra kompleksa škrob-trijodid, uspješno je razvrstala škrobove na osnovi njihove pripadnosti vrstama te sortama unutar iste vrste. Metoda je jednostavnija i praktičnija za uporabu od standardnih dugotrajnih metoda.The botanical origin of starch is of importance in industrial applications and food processing because it may influence the properties of the final product. Current microscopic methods are time-consuming. Starch consists of an origin-dependent amylose/amylopectin ratio. Triiodide ions bind characteristically to the amylose and amylopectin depending on the botanical origin of the starch. The absorbance of the starch-triiodide complex was measured for wheat, potato, corn, rye, barley, rice, tapioca and unknown origin starch, and within the different cultivars. Each starch sample had specific parameters: starch-triiodide complex peak wavelength maximum (λmax/nm), maximum absorbance change at λmax (ΔA) and λmax shift towards the unknown origin starch sample values. The visible absorption spectra (500-800 nm) for each starch sample were used as a unique fingerprint, and then elaborated by cluster analysis. The cluster analysis managed to distinguish data of two clusters, a cereal type cluster and a potato/tapioca/rice starch cluster. The cereal subclusters extensively distinguished wheat/barley/rye starches from corn starches. Data for cultivars were mostly in good agreement within the same subclaster. The proposed method that combines cluster analysis and visible absorbance data for starch-triiodide complex was able to distinguish starch of different botanical origins and cultivars within the same species. This method is simpler and more convenient than standard time-consuming methods

Coumarin derivatives act as novel inhibitors of human dipeptidyl peptidase III: combined in vitro and in silico study

Dipeptidyl peptidase III (DPP III), a zinc- dependent exopeptidase, is a member of the metalloproteinase family M49 with distribution detected in almost all forms of life. Although the physiological role of human DPP III (hDPP III) is not yet fully elucidated, its involvement in pathophysiological processes such as mammalian pain modulation, blood pressure regulation, and cancer processes, underscores the need to find new hDPP III inhibitors. In this research, five series of structurally different coumarin derivatives were studied to provide a relationship between their inhibitory profile toward hDPP III combining an in vitro assay with an in silico molecular modeling study. The experimental results showed that 26 of the 40 tested compounds exhibited hDPP III inhibitory activity at a concentration of 10 µM. Compound 12 (3-benzoyl-7-hydroxy-2H-chromen-2-one) proved to be the most potent inhibitor with IC50 value of 1.10 μM. QSAR modeling indicates that the presence of larger substituents with double and triple bonds and aromatic hydroxyl groups on coumarin derivatives increases their inhibitory activity. Docking predicts that 12 binds to the region of inter-domain cleft of hDPP III while binding mode analysis obtained by MD simulations revealed the importance of 7- OH group on the coumarin core as well as enzyme residues Ile315, Ser317, Glu329, Phe381, Pro387, and Ile390 for the mechanism of the binding pattern and compound 12 stabilization. The present investigation, for the first time, provides an insight into the inhibitory effect of coumarin derivatives on this human metalloproteinase

Water for all : Proceedings of the 7th international scientific and professional conference Water for all

The 7th International Scientific and Professional Conference Water for all is organized to honour the World Water Day by the Josip Juraj Strossmayer University of Osijek, European Hygienic Engineering & Design Group (EHEDG), Danube Parks, Croatian Food Agency, Croatian Water, Faculty of Food Technology Osijek, Faculty of Agriculture in Osijek, Faculty of Civil Engineering Osijek, Josip Juraj Strossmayer University of Osijek Department of Biology, Josip Juraj Strossmayer University of Osijek Department of Chemistry, Nature Park “Kopački rit”, Osijek- Baranja County, Public Health Institute of the Osijek- Baranja County and „Vodovod-Osijek“ -water supply company in Osijek. The topic of World Water Day 2017 was "Wastewater" emphasizing the importance and influence of wastewater treatments on global environment. The international scientific and professional conference Water for all is a gathering of scientists and experts in the field of water management, including chemists, biologists, civil and agriculture engineers, with a goal to remind people about the significance of fresh water and to promote an interdisciplinary approach and sustainability for fresh water resource management. The Conference has been held since 2011. About 300 scientists and engineers submitted 95 abstracts to the 7th International Scientific and Professional Conference Water for all, out of which 33 was presented orally and 62 as posters. 47 full papers were accepted by the Scientific Committee. 38 full papers became the part of the this Proceedings while 9 papers were accepted for publication in Croatian Journal of Food Science and Technology and Electronic Journal of the Faculty of Civil Engineering Osijek - e-GFOS

Brašno - Kruh '15

Proceedings contains 28 original research articles presented at 8th International Congress Flour – Bread ’15 and 10th Croatian Congress of Cereal Technologists Brašno – Kruh ’1

Coumarin derivatives of 1,2,4-triazole - synthesis and biological activity related to plant protection application

U okviru doktorskog rada sintetizirani su kumarinski 1,2,4-triazoli s mogućim višestrukim biološkim učincima vezanim za primjenu u zaštiti bilja. Sinteza je provedena kao one-pot reakcija kumarinskih hidrazida (1 – 3) i različito supstituiranih izotiocijanata u niskotemperaturnom eutektičkom otapalu kolin-klorid : urea (molni omjer 1 : 2), miješanjem na magnetskoj miješalici pri 80 °C. Rezultat su tri serije spojeva: prva, u kojoj je 1,2,4-triazolni prsten povezan -CH2- poveznicom na položaju 4, a hidroksilna je skupina na položaju 7 kumarina (1a – k), te druga serija derivata s 1,2,4-triazolnim prstenom povezanim eterskom poveznicom na položaju 7 kumarina i metilnom skupinom na položaju 4 kumarina (2a – o). Treća, dodatna serija derivata od druge se razlikuje po nedostatku metilne skupine na položaju 4 kumarina (3a – h). Korištenje niskotemperaturnog eutektičkog otapala omogućilo je provođenje reakcije u jednom stupnju, bez primjene katalizatora i organskih otapala štetnih za okoliš. Zbog pojednostavljene izolacije i pročišćavanja produkata, skraćeno je vrijeme trajanja postupka u odnosu na konvencionalnu i druge objavljene metode. Derivati kumarinskih 1,2,4-triazola su dobiveni u prinosima od 25 do 91 %, a njihove su strukture potvrđene masenom spektrometrijom te 1H i 13C NMR spektroskopijom. Svim priređenim spojevima računalno je procijenjena sličnost s pesticidima te toksičnost za čovjeka i okoliš. Utvrđeno je kako većina spojeva ima povoljan toksikološki profil u odnosu na komercijalne triazolne pesticide. Antifungalno djelovanje in vitro ispitano je na četiri fitopatogene gljive, a antibakterijsko djelovanje na dvije fitopatogene i dvije zemljišno-korisne bakterije. Kumarinski 1,2,4-triazoli uspješno su inhibirali rast micelija gljiva, s izraženim antifungalnim djelovanjem druge serije derivata na Sclerotinia sclerotiorum i Fusarium oxysporum. Sintetizirani spojevi nisu imali antibakterijski učinak ni na patogene ni na zemljišno-korisne bakterije. Na temelju rezultata antifungalnog djelovanja provedena je analiza kvantitativnog odnosa strukture i aktivnosti (QSAR) spojeva. Model za djelovanje na S. sclerotiorum razvijen je pomoću tri deskriptora (nR=Ct, RDF095m i HATS1e) i može objasniti 79 % inhibitornog djelovanja kumarinskih 1,2,4-triazola. Model za djelovanje na F. oxysporum razvijen je pomoću četiri deskriptora (R4u+, nAROR, RDF080e i Mor11u), a može objasniti 77 % inhibitornog djelovanja spojeva. Pouzdanost razvijenih modela potvrđena je metodama unutarnje i vanjske procjene valjanosti. Potencijalni mehanizam antifungalnog djelovanja istražen je metodom molekulskog uklapanja spojeva u enzime važne za rast micelija (sterol 14α-demetilazu, hitinaze A i B, N-miristoil transferazu) te enzime potrebne za razaranje stanične stijenke domaćina (proteinazu K, endoglukanazu I te endopoligalakturonaze I i II). Spojevi su se dobro uklopili u aktivna mjesta demetilaze, hitinaza A i B, proteinaze K te endopoligalakturonaza I i II. Unatoč dobrim energijama uklapanja, spojevi nisu uspjeli ostvariti interakcije u aktivnim mjestima N-miristoiltransferaze i endoglukanaze. Iz dobivenih rezultata može se zaključiti kako su derivati druge serije kumarinskih triazola potencijalni inhibitori demetilaze, obje hitinaze ili proteinaze K, dok su derivati prve serije spojeva inhibitori endopoligalakturonaza. Spoj 2j ističe se svojim antifungalnim djelovanjem i procjenjenom niskom toksičnosti, što ga čini dobrim kandidatom za razvoj novog aktivnog sastojka sredstava za zaštitu bilja.In this doctoral thesis, coumarin 1,2,4-triazoles with potential multiple biological effects related to application in plant protection were synthesized. The synthesis was carried out as a one-pot reaction of coumarin hydrazides (1 – 3) and differently substituted isothiocyanates in a deep eutectic solvent, choline chloride : urea (molar ratio 1 : 2), by stirring with a magnetic stirrer at 80 °C. The result is three series of compounds: the first in which the 1,2,4-triazole ring is connected by a -CH2- linker at position 4 and the hydroxyl group is at position 7 of the coumarin (1a – k), and the second series of derivatives with a 1,2,4-triazole ring connected by an ether linker at position 7 of the coumarin and a methyl group at position 4 of the coumarin (2a – o). The third, additional series of derivatives, differs from the second by the absence of a methyl group at position 4 of coumarin (3a – h). The use of a deep eutectic solvent enabled to carry out the reaction in one step without the need to use catalysts and environmentally harmful organic solvents. The simplified isolation and purification of the products shortened the duration of the process compared to conventional and other published methods. The derivatives of coumarin 1,2,4-triazoles were obtained in yields of 25 to 91 %, and their structures were confirmed by mass spectrometry and 1H and 13C NMR spectroscopy. All prepared compounds were evaluated in silico for their similarity to pesticides and their toxicity to humans and the environment. Most of the compounds were found to have a favorable toxicological profile compared to commercial triazole pesticides. The antifungal activity was tested in vitro on four phytopathogenic fungi, and the antibacterial activity on two phytopathogenic and two soil-beneficial bacteria. Coumarin 1,2,4-triazoles successfully inhibited the growth of fungal mycelia, with the second series of derivatives showing pronounced antifungal activity on Sclerotinia sclerotiorum and Fusarium oxysporum. The synthesized compounds did not show antibacterial activity, neither on the pathogens nor on the soil-beneficial bacteria. Based on the results of antifungal activity, a quantitative structure-activity relationship (QSAR) analysis of the compounds was performed. The model for the effect on S. sclerotiorum was developed using three descriptors (nR=Ct, RDF095m and HATS1e) and can explain 79 % of the inhibitory effect of coumarin 1,2,4-triazoles. The model for the effect on F. oxysporum was developed using four descriptors (R4u+, nAROR, RDF080e and Mor11u) and can explain 77 % of the inhibitory effect of the compounds. The reliability of the developed models was confirmed by internal and external validation methods. The potential mechanism of antifungal activity was investigated by means of molecular docking of the compounds to the enzymes important for mycelial growth (sterol 14α-demethylase, chitinases A and B, N-myristoyltransferase) and enzymes necessary for host cell wall destruction (proteinase K, endoglucanase I and endopolygalacturonase I and II). The compounds fit well into the active sites of demethylase, chitinases A and B, proteinase K, and endopolygalacturonase I and II. Despite good fitting energies, the compounds failed to achieve interactions in the active sites of N-myristoyltransferase and endoglucanase. From the obtained results, it can be concluded that the derivatives of the second series of coumarin triazoles are potential inhibitors of demethylase, chitinases or proteinase K, while the derivatives of the first series of compounds are inhibitors of endopolygalacturonases. Compound 2j stands out for its antifungal activity and its estimated low toxicity, which emphasized it as a good candidate for the development of a new active ingredient for plant protection products

Development of a Direct Potentiometric Method for the Determination of Amylase Activity in Barley Malt

Slad je produkt žitarica, najčešće ječma, koji se koristi u pićima i hrani kao podloga za fermentaciju te za dodavanje okusa. Dobiva se klijanjem ječma u kontroliranim uvjetima što omogućava sintezu enzima amilaza, koje embrio biljke koristi za razgradnju škroba. Amilaze su enzimi koji kataliziraju hidrolizu škroba na jednostavnije ugljikohidrate. U ječmu se nalaze dvije vrste amilaza, alfa i beta amilaze, koje se razlikuju po načinu razgradnje škroba. Aktivnost alfa amilaze u sladu ključni je parametar kvalitete za žitarice i brašno u prehrambenoj industriji, posebice u proizvodnji piva i fermentaciji. Također, različite koncentracije alfa amilaze koriste se za modifikaciju svojstava tijesta što uvelike utječe na kvalitetu pečenih proizvoda. U ovom je radu predložena elektrokemijska metoda za određivanje aktivnosti amilaza u sladu. Metoda je temeljena na direktnom potenciometrijskom mjerenju koncentracije trijodidnih iona oslobođenih iz škrob-trijodid kompleksa nakon razgradnje škroba pomoću amilaza iz slada. Kao detektor trijodidnih iona predložena je platinska redoks elektroda. U odnosu na druge dostupne metode, ovaj princip određivanja je jednostavan, brz, jeftin i ne zahtjeva specifične reagense i aparaturu. Rad također sadrži i metodički dio s prijedlogom pripreme za nastavni sat kemije u osnovnoj školi, uključujući i radne listiće s pokusima na temu enzimi.Malt is a grain product, mostly barley, used in beverages and foods as a basis for fermentation and to add flavour. The malt is obtained in barley grain germinating process under controlled conditions that enables the synthesis of amylase enzymes which are used later by plant embryo in order to breakdown starch molecules. Amylases are enzymes that catalyze hydrolysis of starch into smaller carbohydrate molecules. Two main subtypes of amylases can be found in barley malt, alpha and beta, that differ in the way they breakdown the starch molecules. The level of alpha-amylase in malt is a key quality parameter for grains and flour in food industry, mainly in beer production and fermentation. Furthermore, variable concentrations of alpha-amylase are used to modify dough properties, thus influencing the quality of the baked products. The proposed electrochemical method in this paper is based on direct potentiometric determination of levels of triiodide ion released from the starch–triiodide complex after starch degradation by barley malt amylases. A platinum redox electrode is proposed as a detector of triiodide ions. When compared to other available methods, this principle is simple, rapid, inexpensive and doesn't require specific reagents and apparatus. In the teaching part of the thesis a preparation lecture on enzymes for the elementary school chemistry class is proposed. The lecture includes some relevant experiments, questionnaires and handouts