Correlation of structure and chromatographic behavior of the polioxygenated steroids by the means of thin-layer chromatography

U okviru ove doktorske disertacije detaljno je proučavan uticaj supstituenata vezanih za A prsten na hromatografsko ponašanje serije polioksigenovanih steroida u uslovima tankoslojne hromatografije. U cilju proučavanja uticaja polarnosti sorbenta na retenciju ispitivanih jedinjenja upotrebljena su dva veoma različita sorbenta: polarni nemodifikovani silika-gel i nepolarni C-18 modifikovani silika-gel. Posebna pažnja posvećena je razmatranju uticaja sastava primenjenih mobilnih faza na retenciju radi što boljeg razumevanja odnosa hromatografskog ponašanja i lipofilnosti ispitivanih jedinjenja. Uzimajući u obzir svojstva sorbenta kao i korišćenih mobilnih faza, retenciono ponašanje je izučavano u uslovima normalno-fazne i reverzno-fazne hromatografije. Kao tipični normalnofazni sistemi upotrebljeni su polarni silika-gel kao stacionarna faza i manje polarni rastvarači (aceton, heksan, acetonitril, dihlormetan) kao mobilna faza. Reverzno-fazni sistemi sastojali su se od smeše voda ˗ organski rastvarač (aceton, metanol ili acetonitril) i oktadecil modifikovanog silika-gela kao stacionarne faze. U uslovima normalno-fazne hromatografije sistem aceton/nheksan se pokazao kao pogodan za ispitivanje uticaja sastava mobilne faze na hromatografsko ponašanje polioksigenovanih steroidnih jedinjenja. U uslovima reverzno-fazne hromatografije najbolja selektivnost je postignuta primenom mobilne faze metanol - voda. U okviru ovog rada proučena je i mogućnost primene tankoslojne hromatografije za brzo i jednostavno određivanje lipofilnosti kao važnog parametra biološke aktivnosti ispitivanih steroida. Utvrđeno je da postoji linearna zavisnost između retencionih parametara ispitivanih jedinjenja i sastava dvokomponetnih mobilnih faza. Ispitivanjem korelacije između hromatografski određenih parametara lipofilnosti i teorijski izračunatih logP vrednosti utvrđeno je da je reverzno-fazna hromatografija pogodnija za procenu lipofilnosti ispitivanih jedinjenja.Takođe pokazano je da ispitivani polioksigenovani steroidi sa supstituisanim A prstenom predstavljaju kongenernu seriju. Primenom višestruke linearne regresije (multiple linear regression, MLR) i metode parcijalne regresije najmanjih kvadrata (partial least squares, PLS) proučavane su moguće zavisnosti između hromatografskog ponašanja i molekulskih svojstava analita. Na osnovu statističkih parametara dobijenih za tri reverzno-fazna hromatografska sistema najbolje korelacije između RM 0 i deskriptora bile su u sistemu C-18 / metanol-voda što izdvaja ovaj hromatografski sistem kao najpogodniji za određivanje lipofilnosti analita. Na osnovu regresionih modela određeni su deskriptori koji najbolje opisuju ponašanje analita u odnosu na utvrđene retencione parametre. Dobijeni su statistički značajni modeli kvantitativnog odnosa strukture i retencije (QSRR). Izračunata lipofilnost izražena kao XlogP, površinski napon (ST) i Hansenovo vodonično vezivanje (HHB) su deskriptori koji najbolje opisuju QSRR i u višestrukoj linearnoj regresiji i u parcijalnoj regresiji najmanjih kvadrata.The framework of this thesis was to thoroughly investigate influence of structural moiety attached to A ring on chromatographic behavior of series polyoxigenated steroids under thin-layer chromatography conditions. In order to examine the effect of sorbent polarity on retention behavior of the investigated substances, two different sorbents were selected: polar unmodified silica gel and non-polar C-18 modified silica. In addition, influence of the mobile phase composition was discussed with view to determine relationship between chromatographic behavior and lipophilicity. Taking into account the nature of both sorbents and chromatographic solvents used, the chromatographic behavior of the substances was investigated under normal- and reversed-phase conditions. Polar silica gel with less polar solvents was used as typical normal-phase systems, whereas alkyl modified silica gel (RP-18 silica) in combination with polar water–organic mobile phases (methanol, acetone or acetonitrile) - for typical reversed-phase separation. It was found that in normal-phase chromatography acetone/n-hexane was more suitable for studying relationship between chromatographic behavior of the polioxigenated steroids and mobile phase composition. Under reversed-phase condition the best selectivity was achieved by the use of methanol-water mobile phase. An additional goal of this thesis was to investigate possibility of application of thin-layer chromatography for rapid and simple determination of lipophilicity as parameter of special importance for biologically active substances. A linear relationship between retention parameters of the investigated compounds and composition of the binary mobile phase used was established. On the basis of correlation between chromatographically determined lipophilicity and calculated logP values it was found that reversed-phase chromatography is useful method for lipophilicity estimation. In addition, it is appear that investigated polyoxigenated steroids represent a congeneric series of compounds. Chromatographically determined parameters of lipophilicity (RM 0) were used for developing appropriate models for structure-retention relationships by multivariate statistical analysis. The retention data for system methanol-water on C-18 silica phase has the most significant correlation between RM 0 and descriptors indicating this chromatographic system as most suitable for lipophilicity determination of the studied compounds. Retention data were correlated to molecular characteristics of the analytes with view to examine possible relationships by the means of multiple linear regression and partial least square regression. On the basis of comparison of the statistical parameters obtained for both multiple linear regression and partial least square regression models, descriptors best describing the analyte behavior were selected. Statistically significant and physically meaningful structure-retention relationships were obtained. Calculated lipophilicity expressed as XlogP as well surface tension and Hansen hydrogen bonding was included in both multiple linear regression and partial least square regression models

White-rot fungal pretreatment of wheat straw: effect on enzymatic hydrolysis of carbohydrate polymers

The aim of the study was the comparative analysis of degradation of wheat straw lignin by white-rot fungi and its implications on the efficiency of enzymatic hydrolysis of holocellulose. Peroxidases were found to be predominantly responsible for lignin degradation, even though high laccase activities were detected, especially in the initial stages of fungal culturing. The studied fungal species showed various ability to degrade lignin in wheat straw, which further affected the release of reducing sugars during enzymatic saccharification. The highest rate of lignin, hemicelluloses and cellulose degradation was noticed in the sample pretreated with Irpex lacteus. Among all the tested species, only Ganoderma resinaceum was found as a suitable lignin degrader, with 2-fold higher hydrolysis yield (51.1 ± 4.7%) than in the control. A key mechanism that enhances convertibility of carbohydrates is the selective lignin removal from biomass. Operating time, holocellulose loss and unpredictable fungal response to culturing conditions are the main challenges in fungal pretreatment of lignocellulosic feedstock

Comparison of Sugar Profile between Leaves and Fruits of Blueberry and Strawberry Cultivars Grown in Organic and Integrated Production System

The objective of this study was to determine and compare the sugar profile, distribution in fruits and leaves and sink-source relationship in three strawberry ('Favette', 'Alba' and 'Clery') and three blueberry cultivars ('Bluecrop', 'Duke' and 'Nui') grown in organic (OP) and integrated production systems (IP). Sugar analysis was done using high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD). The results showed that monosaccharide glucose and fructose and disaccharide sucrose were the most important sugars in strawberry, while monosaccharide glucose, fructose, and galactose were the most important in blueberry. Source-sink relationship was different in strawberry compared to blueberry, having a much higher quantity of sugars in its fruits in relation to leaves. According to principal component analysis (PCA), galactose, arabinose, and melibiose were the most important sugars in separating the fruits of strawberries from blueberries, while panose, ribose, stachyose, galactose, maltose, rhamnose, and raffinose were the most important sugar component in leaves recognition. Galactitol, melibiose, and gentiobiose were the key sugars that split out strawberry fruits and leaves, while galactose, maltotriose, raffinose, fructose, and glucose divided blueberry fruits and leaves in two groups. PCA was difficult to distinguish between OP and IP, because the stress-specific responses of the studied plants were highly variable due to the different sensitivity levels and defense strategies of each cultivar, which directly affected the sugar distribution. Due to its high content of sugars, especially fructose, the strawberry cultivar 'Clery' and the blueberry cultivars 'Bluecrop' and 'Nui' could be singled out in this study as being the most suitable cultivars for OP

Leaf Soluble Sugars and Free Amino Acids as Important Components of Abscisic Acid-Mediated Drought Response in Tomato

Water deficit has a global impact on plant growth and crop yield. Climate changes are going to increase the intensity, duration and frequency of severe droughts, particularly in southern and south-eastern Europe, elevating the water scarcity issues. We aimed to assess the contribution of endogenous abscisic acid (ABA) in the protective mechanisms against water deficit, including stomatal conductance, relative water potential and the accumulation of osmoprotectants, as well as on growth parameters. To achieve that, we used a suitable model system, ABA-deficient tomato mutant, flacca and its parental line. Flacca mutant exhibited constitutively higher levels of soluble sugars (e.g., galactose, arabinose, sorbitol) and free amino acids (AAs) compared with the wild type (WT). Water deficit provoked the strong accumulation of proline in both genotypes, and total soluble sugars only in flacca. Upon re-watering, these osmolytes returned to the initial levels in both genotypes. Our results indicate that flacca compensated higher stomatal conductance with a higher constitutive level of free sugars and AAs. Additionally, we suggest that the accumulation of AAs, particularly proline and its precursors and specific branched-chain AAs in both, glucose and sucrose in flacca, and sorbitol in WT, could contribute to maintaining growth rate during water deficit and recovery in both tomato genotypes

Supplementary data for the article: Waisi, H.; Janković, B.; Nikolić, B.; Dragičević, V.; Panić, I.; Tosti, T.; Trifković, J. Influence of Various Concentrations of 24-Epibrassinolide on the Kinetic Parameters during Isothermal Dehydration of Two Maize Hybrids. South African Journal of Botany 2018, 119, 69–79. https://doi.org/10.1016/j.sajb.2018.08.006

Supplementary material for: [https://doi.org/10.1016/j.sajb.2018.08.006]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/342

The Effect of Green Extraction Technologies on the Chemical Composition of Medicinal Chaga Mushroom Extracts

The mushroom industry should implement green extraction technologies; however, there is not enough information on the differences between these techniques expressed as the chemical composition of the resulting extract. In this study, selected types of green extraction techniques (GETs) were used on Chaga (Inonotus obliquus) (Fr.) Pilát from Serbia (IS) and Mongolia (IM) to examine the differences that would enable the composition-based technology choices in the mushroom supplement industry. Subcritical water extraction (SWE), microwave-assisted (MW) extraction, and ultrasonic-assisted extraction (VAE) were used to prepare the extracts. SWE was performed at two different temperatures (120 and 200 °C), while 96% ethanol, 50% ethanol, and water were used for MW and VAE. The yield, the content of total phenols, total proteins, and carbohydrates, qualitative and quantitative analysis of phenolic compounds, carbohydrates, including α- and β- and total glucans, and fatty acids, were determined in the obtained extracts. SWE resulted in a significantly higher yield, total polysaccharide, and glucan content than any other technique. Glucose was the most dominant monosaccharide in the SWE samples, especially those extracted at 200 °C. The MW 50% EtOH extracts showed the highest yield of total phenols. Among the tested phenolic compounds, chlorogenic acid was the most dominant. SWE can be recommended as the most efficient method for extracting commercially important compounds, especially glucans and phenols

The Polyphenols as Potential Agents in Prevention and Therapy of Prostate Diseases.

In recent years, the progress of science and medicine greatly has influenced human life span and health. However, lifestyle habits, like physical activity, smoking cessation, moderate alcohol consumption, diet, and maintaining a normal body weight represent measures that greatly reduce the risk of various diseases. The type of diet is very important for disease development. Numerous epidemiological clinical data confirm that longevity is linked to predominantly plant-based diets and it is related to a long life; whereas the western diet, rich in red meat and fats, increases the risk of oxidative stress and thus the risk of developing various diseases and pre-aging. This review is focused on the bioavailability of polyphenols and the use of polyphenols for the prevention of prostate diseases. Special focus in this paper is placed on the isoflavonoids and flavan-3-ols, subgroups of polyphenols, and their protective effects against the development of prostate diseases

Preliminary investigation of aromatic fraction composition indust extract from the Library of the Facility of Chemistry in Belgrade

Usled modernog načina života ljudi provode oko 90 % vremena u zatvorenim prostorijama, kao što su kuće/stanovi, kancelarije, automobili itd. Prašina je sve prisutna u svim pomenutim sredinama i nalazi se kao čestice suspendovane u vazduhu ili istaložena na površinama. Čestice prašine se mogu lako udahnuti i mogu da oštete respiratorni sistem i pluća. Pored toga, čestice prašine akumuliraju hemikalije iz zatvorenih prostorija i predstavljaju važan put izlaganja ljudi tim jedinjenjima. U kućnoj prašini se mogu naći ftalati, policiklični aromatični ugljovodonici i ostala poluisparljiva jedinjenja. Ftalati se često koriste kao plastifikator u proizvodnji polivinil hlorida (PVC-a) i predmeta opšte upotrebe kao što su građevinski materijal, dečije igračke i nameštaj, ali i u proizvodnji podnih obloga, veštačke kože, lepkova, tepiha, maziva, cevi, žica, sredstava za čišćenje kuće, proizvoda za negu tela (fiksatori mirisa, proizvodi za negu kože, pene i šamponi) i ambalaže za namirnice. Primena ftalata zavisi od njihove molekulske mase. Ftalati male molekulske mase, kao što su di-metil-ftalat (DMP), di-etil-ftalat (DEP), di-propil-ftalat (DPP), di-izobutil-ftalat (DiBP), di-n-butil ftalat (DBP), di-n-pentil-ftalat (DNPP) i benzil- butil-ftalat (BBP), se koriste u rastvaračima, lepkovima, voskovima, mastilu, lekovima, kozmetici i insekticidima.Visokomolekulski ftalati, kao di-2-etilheksil-ftalat (DEHP), di- ciklo-heksil-ftalat (DCHP) i di-izo-nonil-ftalat (DiNP), su plastifikatori u PVC proizvodima i predmetima od opšte upotrebe. Estri ftalata su povezani sa velikim brojem zdravstvenih problema kod ljudi. Pre svega, ftalati deluju kao endokrini disruptori i doprinose stvaranju varijacija u reprodukcionom sistemu kao što su opadanje broja spermatozoida, oštećenje DNK u spermatozoidima, prevremeni razvoj dojki i promena u reproduktivnim hormonima. Ftalati utiču na pojavu astme, alergija i poremećaja funkcije nervnog sistema. Pored toga, DEHP je okarakterisan kao 2b kancerogena supstanca, tj. kao potencijalno kancerogen za ljude, od strane IARC-a (Međunarodna agencija za istraživanje raka, eng. International Agency for Research on Cancer). Treba napomenuti da su pojedini metaboliti ftalata često toksičniji od samih nepromenjenih ftalata. Ljudi mogu biti izloženi ftalatima inhalacijom, ingestijom i apsorpcijom preko kože. Oko 1 g istaložene prašine je sakupljen iz biblioteke Hemijskog fakulteta u Beogradu, sa visine iznad 1m od poda. Uzorci su odmereni, ekstrahovani, prečišćeni i aromatična frakcija je snimljena metodom gasne hromatografije, povezanom sa masenim spektrometrom. Lokacija uzorkovanja i hromatogram aromatične frakcije je prikazan na slici 1. Dobijeni rezultati ukazuju na to da, pored prirodnih proizvoda kao što su metil estri masnih kiselina (koje su najverovatnije znatno obilnije u alifatičnoj frakciji), uzorak sadrži 3,5-di- terc-butil-4-hidroksibenzaldehid, metabolit 2,6-di-terc-butil-4-methilfenola, koji se koristi kao antioksidans u namirnicama i kozmetičkim proizvodima [3]. Najzastupljenija jedinjenja u aromatičnoj frakciji su DiBP), DBP i DEHP. Interesantno je primetiti da se detektovani ftalati koriste u dve različite svrhe, kao aditivi u plastici i drugim proizvodima (DiBP i DBP) i kao plastifikatori u polimerima (DEHP). Kao što je prethodno pomenuto, DEHP je klasifikovan kao potencijalno kancerogena supstanca za ljude. Pored toga, primena DiBP, DBP i DEHP je ograničena od strane Evropske komisije. Zbog prisustva ftalata koji imaju veliki uticaj na ljudsko zdravlje u ekstraktu prašine, potrebno je izvršiti dodatna ispitivanja na većem broju uzoraka i uraditi detaljnu kvantifikaciju i procenu rizika po ljudsko zdravlje.Постерска презентација представљена је на 9. симпозијуму Хемија и заштита животне средине ENVIROCHEM2023 са међународним учешћем у Кладову, Србија у периоду од 04. до 07. јуна 2023. године

Chemical Constituents of Stinging Nettle (Urtica dioica L.): A Comprehensive Review on Phenolic and Polyphenolic Compounds and Their Bioactivity

Polyphenolic compounds are of great interest in today’s science. Naturally, they occur in plants and other sources in many different forms. Their wide range of biological activity has attracted the attention of the scientific community. One of the sources of phenolic compounds is stinging nettle (Urtica dioica L.), a common plant in almost all parts of the world. A long tradition of utilization and an interesting chemical profile make this plant a fascinating and extensive object of study. The chemical profile also allows this plant to be used as a food and a pigment source in the food, pharmaceutical, and cosmetic industries. Previously conducted studies found phenolic acids and polyphenolic compounds in root, stalk, and stinging nettle leaves. Different extraction techniques were usually used to isolate them from the leaves. Obtained extracts were used to investigate biological activity further or formulate different functional food products. This study aimed to collect all available knowledge about this plant, its chemical composition, and biological activity and to summarize this knowledge with particular attention to polyphenolic compounds and the activity and mechanisms of their actions

Supplementary material for the article: Mesarović, J.; Trifković, J.; Tosti, T.; Fotirić Akšić, M.; Milatović, D.; Ličina, V.; Milojković-Opsenica, D. Relationship between Ripening Time and Sugar Content of Apricot (Prunus Armeniaca L.) Kernels. Acta Physiologiae Plantarum 2018, 40 (8). https://doi.org/10.1007/s11738-018-2731-7

Supplementary material for: [https://doi.org/10.1007/s11738-018-2731-7]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2193