375 research outputs found

    Study of Hydrophobic Domains in Humic Acids

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    Fyzik√°lnńõ-chemick√° povaha hydrofobn√≠ch dom√©n huminov√Ĺch kyselin byla studov√°na z nńõkolika hledisek. K objasnńõn√≠ v√Ĺznamu fluorescenńćn√≠ch spekter byly vzorky podrobeny sekvenńćn√≠ frakcionaci, kter√° pomohla k ńć√°steńćn√©mu objasnńõn√≠ vlivu vodorozpustn√Ĺch sloŇĺek, voln√Ĺch a v√°zan√Ĺch lipidŇĮ na optick√© vlastnosti huminov√Ĺch kyselin. V√Ĺsledky naznańćily, Ňĺe fluorescenńćn√≠ p√≠ky tradińćnńõ pŇôiŇôazovan√© superpozici jednotliv√Ĺch struktur jsou sp√≠Ň°e dŇĮsledkem agregańćn√≠ch vlastnost√≠ huminov√Ĺch molekul tvoŇô√≠c√≠ch vlivem hydrofobn√≠ho efektu zd√°nlivńõ vysoce aromatick√© struktury. D√°le pak bylo zjiŇ°tńõno, Ňĺe na optick√Ĺch vlastnostech huminov√Ĺch kyselin maj√≠ pod√≠l i molekuly, kter√© nemaj√≠ prim√°rnńõ fluoroforn√≠ nebo chromoforn√≠ vlastnosti. Tento pohled je v souladu s teori√≠ supramolekul√°rn√≠ho uspoŇô√°d√°n√≠ huminov√Ĺch kyselin. D√°le byly studov√°ny agregace, konformańćn√≠ chov√°n√≠ a termodynamick√° stabilita huminov√Ĺch kyselin pomoc√≠ metody vysoce rozliŇ°ovac√≠ ultrazvukov√© spektroskopie. Bylo prok√°z√°no, Ňĺe huminov√© kyseliny maj√≠ schopnost agregovat uŇĺ od velmi n√≠zk√Ĺch koncentrac√≠ (The nature of hydrophobic domains in humic acids was studied from different points of view. To shed light on the meaning of fluorescent spectra, the measured samples underwent the sequential extraction which partially revealed the role of water-soluble components, free and bond lipids in optical properties of humic acids. The results indicated that the fluorescence peaks traditionally attributed to the superposition of individual chemical structures are rather a result of aggregation properties of humic molecules and hydrophobic effect driving aromatic molecules together forming aggregates apparently large molecular weight. Further, it seems that there is a significant influence of non-fluorophores and non-chromophores on the optical properties of humic acids. Results are consistent with the theory on supramolecular structure of humic acids. Next, the aggregation, conformational behaviour and thermodynamic stability of humic acids were studied by high resolution ultrasonic spectroscopy. It was demonstrated that humic molecules are able to interact and form aggregates at very low concentration (

    The impact of the counterion in the performance of ionic hydrotropes

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    The efficiency of an ionic hydrotrope is shown to increase with the hydrophobicity of its counterion, challenging the common view that ionic hydrotropes should possess a small, densely charged counterion such as sodium or chloride.publishe

    Líquidos iónicos como hidrótropos: a chave para o aumento da solubilidade

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    Water solubility of hydrophobic compounds is a crucial factor in the formulation of drugs, cleaning products and personal hygiene. Therefore, technology that allows us to increase their solubility and dissolution rate has attracted considerable interest not only at an academic level but also at an industrial one. In this sense, hydrotropes have been under the spotlight. These compounds are characterized as molecules possessing the capacity of promoting a drastic, several-fold increase in aqueous solubility of highly hydrophobic compounds. Recently, ionic liquids have been appointed as a promising class of catanionic hydrotropes, since both the cation and anion can contribute to the solubility increase. Although there is a vast amount of reviewing work centred on hydrotropy, its underlying mechanism is not yet fully understood. This work proposes to study the impact of salt addition on the hydrotropy phenomenon as to better understand its mechanism, both experimentally and through simulation. Herein the addition of chloride salts to aqueous solutions of an ionic liquid was found to hinder solubility by promoting aggregation of the latter, with a notably nuanced behaviour according to the salt cation valence. Hydrophobic interactions were found to be central to the aggregative effect of the hydrotrope around the solute, which seem to drive hydrotropy. The interactions between the hydrotrope and the solute presented a degree of site-specificity, lost with salt addition. Hydrotrope aggregation showed to be detrimental to the hydrotropic effect, disproving one of the dominant theories justifying the mechanism of hydrotropy.A solubilidade em √°gua de compostos hidrof√≥bicos √© um fator crucial na formula√ß√£o de f√°rmacos, produtos de limpeza e de higiene pessoal. Assim, a tecnologia que permite aumentar a solubilidade e a taxa de dissolu√ß√£o dos mesmos tem atra√≠do um consider√°vel interesse n√£o s√≥ a n√≠vel acad√©mico como industrial. Neste sentido, os hidr√≥tropos t√™m sido alvo de muita aten√ß√£o. Estes compostos s√£o caracterizados como mol√©culas com capacidade de promover um dr√°stico aumento da solubilidade aquosa de compostos fortemente hidrof√≥bicos, aumento este em v√°rias ordens de magnitude. Recentemente, os l√≠quidos i√≥nicos foram apontados como uma classe promissora de hidr√≥tropos catani√≥nicos, uma vez que quer o cati√£o como o ani√£o pode contribuir para o aumento da solubilidade. Embora haja um vasto n√ļmero de trabalho de revis√£o com foco na hidrotropia, o mecanismo de a√ß√£o por detr√°s deste fen√≥meno ainda n√£o est√° claramente entendido. Este trabalho pretende averiguar o impacto da adi√ß√£o de um sal no fen√≥meno de hidrotropia com o intuito de melhor compreender o seu mecanismo, experimentalmente e atrav√©s de simula√ß√£o. A adi√ß√£o de cloretos a solu√ß√Ķes aquosas de um l√≠quido i√≥nico demonstrou prejudicar a solubilidade ao promover a agrega√ß√£o do hidr√≥tropo, com um comportamento com v√°rias nuances, mas limitadamente sob uma ordena√ß√£o de acordo com a val√™ncia do cati√£o do sal adicionado. Intera√ß√Ķes hidrof√≥bicas mostraram-se centrais no efeito de agrega√ß√£o do hidr√≥tropo em volta do soluto, que parece conduzir a hidrotropia. As intera√ß√Ķes entre o hidr√≥tropo e o soluto apresentam um grau de especificidade de local, perdido com a adi√ß√£o de sal. A agrega√ß√£o do hidr√≥tropo mostrou-se prejudicial para o efeito hidrotr√≥pico, refutando uma das principais teorias justificativas do mecanismo da hidrotropia.Mestrado em Bioqu√≠mic

    TITRIMETRIC ANALYSIS OF IBUPROFEN BULK DRUG SAMPLE BY USING UREA AS A HYDROTROPIC SOLUBILIZING AGENT

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    Objective: The objective of this study was to employ hydrotropic solublization technique to facilitate the tirimetric analysis of poorly water soluble drug, ibuprofen precluding the use organic solvent. Methods: In the present investigation, poorly water-soluble anti-inflammatory drug, ibuprofen has been solubilized using 8M of urea as hydrotropic agent for its titrimetric analysis instead of using organic solvent. Results: There was an enhancement in solubility of ibuprofen in 8M urea solution as compared to solubility in distilled water. The mean percent estimation of ibuprofen estimated in bulk sample by Indian Pharmacopoeial Method is 98.56% while by the proposed method (using 8M urea) is 98.67%. The results of analysis by the proposed method are very close to the results of the standard method. Conclusion: Proposed method is simple, economic, accurate, eco-friendly and can be successfully employed in the routine quantitative analysis of drug in bulk drug and dosage form in industries

    SOLUBILITY ENHANCEMENT OF NORFLOXACIN BY HYDROTROPY TECHNIQUE

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    The objective of this study is to improve the solubility of poorly water soluble anti-bacterial drug Norfloxacin by hydrotropic solubilization technique. For the present study sodium benzoate was used as hydrotropic agent. By using this hydrotropic agent as water soluble carrier, hydrotropic solid dispersions of Norfloxacin were prepared.in 1:1, 1:2, 1:3 and 1:4 ratios (drug: hydrotropic agent). Equilibrium solubilization of pure drug and hydrotropic solid dispersions of Norfloxacin in distilled water by excess solute method and solubility enhancement ratios were calculated by measuring the absorbance of the solutions at 274.80 nm using UV spectrophotometer. The hydrotropic agent did not interfere in analysis. The results showed that there was an increase in the solubility of Norfloxacin with hydrotropic solid dispersions compared to pure drug in distilled water. There was 9.56 fold enhancement in aqueous solubility of Norfloxacin with hydrotropic solid dispersion of 1:4 ratio compared to 1:1 (6.29), 1:2 (7.09) and 1:3 (8.59) ratios

    HYDROTROPIC EXTRACTION OF THEOBROMINE FROM COCOA BEAN SHELL.

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    Cocoa bean shell (CBS) is a waste product from chocolate and cocoa milling industries. CBS is high in nutritive value but it is of limited use in animal feeds because of its toxic theobromine content. Though its theobromine content limited the use of CBS, its amino acid profile of CBS compares favourably with palm kernel cake suggesting that it could be utilized as a medium protein source to substitute grain protein in livestock diets. Theobromine is also possesed many farmacological function such as anti cancer, diuretics, cardiac stimulants, hypocholesterolemic, smooth-muscle relaxants, atshma and coronary vasodilators. Considering that Indonesia is the third largest producer of cocoa in the, the potential usage of both protein and theobromine content of cocoa bean shell, thus it is neccesary to separate theobromine from cocoa bean shell. A new developed separation process is the extraction process using aqueous hydrotropes solution for recovery of naturally occurring secondary metabolites. The solubility of the secondary metabolites extracted are increased sharply and easily recovered. Recently several researches demonstrated that high solubilization capacity and selectivity in solubilization by hydrotropy could be used for extraction of water insoluble bioactive compound such as piperin, limonin, curcuminoids and forskolin. Based on the promising result by hydrotropic extraction of natural product, thus it is a promising method in administering theobromine from cocoa bean shell. Keywords: hydrotropic, extraction, theobromine, cocoa bean shel

    Inhibition of Protein Aggregation: Supramolecular Assemblies of Arginine Hold the Key

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    BACKGROUND: Aggregation of unfolded proteins occurs mainly through the exposed hydrophobic surfaces. Any mechanism of inhibition of this aggregation should explain the prevention of these hydrophobic interactions. Though arginine is prevalently used as an aggregation suppressor, its mechanism of action is not clearly understood. We propose a mechanism based on the hydrophobic interactions of arginine. METHODOLOGY: We have analyzed arginine solution for its hydrotropic effect by pyrene solubility and the presence of hydrophobic environment by 1-anilino-8-naphthalene sulfonic acid fluorescence. Mass spectroscopic analyses show that arginine forms molecular clusters in the gas phase and the cluster composition is dependent on the solution conditions. Light scattering studies indicate that arginine exists as clusters in solution. In the presence of arginine, the reverse phase chromatographic elution profile of Alzheimer's amyloid beta 1-42 (Abeta(1-42)) peptide is modified. Changes in the hydrodynamic volume of Abeta(1-42) in the presence of arginine measured by size exclusion chromatography show that arginine binds to Abeta(1-42). Arginine increases the solubility of Abeta(1-42) peptide in aqueous medium. It decreases the aggregation of Abeta(1-42) as observed by atomic force microscopy. CONCLUSIONS: Based on our experimental results we propose that molecular clusters of arginine in aqueous solutions display a hydrophobic surface by the alignment of its three methylene groups. The hydrophobic surfaces present on the proteins interact with the hydrophobic surface presented by the arginine clusters. The masking of hydrophobic surface inhibits protein-protein aggregation. This mechanism is also responsible for the hydrotropic effect of arginine on various compounds. It is also explained why other amino acids fail to inhibit the protein aggregation

    Bioavailability enhancement

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    The rate and extent (amount) of unmodified medication absorption from its dose form is referred to as bioavailability. It is one of the critical criteria for achieving optimal medication concentration in the systemic circulation. Bioavailability is a significant factor of a drug's therapeutic efficacy, which is determined by the drug's solubility in gastro intestinal fluid. Poor water solubility, sluggish dissolution rate, poor stability of dissolved drug at physiological pH, poor penetration through biological membrane, and extensive first pass metabolism are all signs of a medication with poor bioavailability. To achieve therapeutic plasma concentrations after oral administration of medicines that are weakly water soluble, substantial doses are required.The main issue is low aqueous solubility. Poor solubility continues to be a key difficulty for the pharmaceutical business, which is increasingly recognised as a critical subject in biomedical research. Any medicine that needs to be absorbed must be in the form of an aqueous solution on the absorption side. This article discusses numerous ways for increasing medication bioavailability. Size reduction, solubilizing excipients, colloidal drug delivery systems, Ph adjustment, solid dispersion, complexation, co-solvency micellarsolubilization, hydrotropy, and other approaches are among them

    Green solvents as hydrotropes to enhance the solubility of acetaminophen

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    Mestrado de dupla diploma√ß√£o com a UTFPR - Universidade Tecnol√≥gica Federal do Paran√°Solubility, the ability to dissolve a solute in a solvent, is crucial in pharmaceutical research, influencing drug formulation and bioavailability. Poorly water-soluble drugs, such as acetaminophen (ACP), a world-wide used drug as painkiller and antipyretic, often present challenges. The addition of hydrotropes to aqueous solutions is one of the strategies used to enhance the solubility of those solutes in water. This study compares the effect of various hydrotrope types (organic compounds, ionic liquids, deep eutectic solvents and organic or inorganic salts) at different concentrations. New solubility data in aqueous solutions of [BMIm][Ac], ChBr, ChCl, NaBS, NaCapry, NaSCN, NaSal, Na2SO4, NaTOS, NH4SCN, (NH4)2SO4, urea, ethanol, 1,2-propanediol, glycerol and acetone were measured at 298.2 K by the shake-flask method coupled to UV-Vis spectroscopy or gravimetry as analytical techniques. A critical comparison with literature data was also carried out. NaTOS, NaSal and [BMIm][Ac] stood out as hydrotropes with better performance, by enhancing the ACP solubility at lower hydrotropic concentrations. Statistical analysis of the hydrotrope polarity assessed using the COSMO-RS model showed a good positive correlation with the apolar factor, at a hydrotrope concentration of 0.10 (weight fraction). At the same hydrotrope concentration, in the studied organic solvents (ethanol, 1,2-propanediol, glycerol and acetone) a strong negative correlation is observed between their hydrogen donor character and the acetaminophen solubility, and an evident negative correlation between the hydrogen bond parameter and the ACP solubility was observed for systems containing ionic liquids. It is necessary to investigate these correlations for other hydrotrope concentrations, and temperatures, attempting to find heuristics that allow the analysis of the drug solubility increase in a predictive way. Finally, it was possible to identify hydrotropes capable of enhancing the solubility of acetaminophen, with potential application in other drugs formulations.A solubilidade, a capacidade do soluto para se dissolver num solvente, √© crucial na investiga√ß√£o farmac√™utica, influenciando a formula√ß√£o e a biodisponibilidade do medicamento. Os f√°rmacos pouco sol√ļveis em √°gua, como o acetaminofeno (ACP), um f√°rmaco mundialmente utilizado como analg√©sico e antipir√©tico, apresentam frequentemente desafios. A adi√ß√£o de hidr√≥tropos a solu√ß√Ķes aquosas √© uma das estrat√©gias utilizadas para aumentar a solubilidade desses solutos em √°gua. Este estudo compara o efeito de v√°rios tipos de hidr√≥tropos (compostos org√Ęnicos, l√≠quidos i√≥nicos, solventes eut√©cticos profundos e sais org√Ęnicos ou inorg√Ęnicos) em diferentes concentra√ß√Ķes. Foram medidos novos dados de solubilidade em solu√ß√Ķes aquosas de [BMIm][Ac], ChBr, ChCl, NaBS, NaCapry, NaSCN, NaSal, Na2SO4, NaTOS, NH4SCN, (NH4)2SO4, ureia, etanol, 1,2-propanodiol, glicerol e acetona a 298,2 K pelo m√©todo do frasco agitado acoplado √† espetroscopia UV-Vis ou gravimetria como t√©cnicas anal√≠ticas. Foi tamb√©m efectuada uma compara√ß√£o cr√≠tica com dados da literatura. NaTOS, NaSal e [BMIm][Ac] destacaram-se como hidr√≥tropos com melhor desempenho, aumentando a solubilidade do ACP em concentra√ß√Ķes hidrotr√≥picas mais baixas. A an√°lise estat√≠stica da polaridade do hidr√≥tropo, avaliada pelo modelo COSMO-RS, mostrou uma boa correla√ß√£o positiva com o fator apolar, a uma concentra√ß√£o de hidr√≥tropo de 0,10 (fra√ß√£o m√°ssica). Para a mesma concentra√ß√£o de hidr√≥tropos, nos solventes org√Ęnicos estudados (etanol, 1,2-propanodiol, glicerol e acetona), observa-se uma forte correla√ß√£o negativa entre o seu car√°cter dador de hidrog√©nio e a solubilidade do acetaminofeno, e uma evidente correla√ß√£o negativa entre o par√Ęmetro de liga√ß√£o de hidrog√©nio e a solubilidade do ACP para os sistemas que cont√™m l√≠quidos i√≥nicos. √Č necess√°rio investigar estas correla√ß√Ķes para outras concentra√ß√Ķes de hidr√≥tropos, e temperaturas, tentando encontrar heur√≠sticas que permitam analisar o aumento da solubilidade do f√°rmaco de forma preditiva. Finalmente, foi poss√≠vel identificar hidr√≥tropos capazes de aumentar a solubilidade do acetaminofeno, com potencial aplica√ß√£o em formula√ß√Ķes de outros f√°rmacos

    Enhancing artemisinin solubility in aqueous solutions: searching for hydrotropes based on ionic liquids

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    Artemisinin is a sesquiterpenoid lactone peroxide, known for its potent antimalarial activity that can be extracted from Artemisia annua L. This compound is only sparingly soluble in water, making its extraction using environmental-friendly and non-toxic aqueous solvents difficult. In the attempt to overcome this limitation, hydrotropes, which are a class of compounds that can assist in increasing the solubility of hydrophobic solutes in water, were investigated in this work. In particular, the hydrotropic capability of ionic liquids (ILs) on the aqueous solubility of artemisinin was studied. The effects of IL concentration and anion nature of 1-butyl-3-methylimidazolium-based ILs on the solubility of artemisinin at 303.2 K in water were evaluated. It is here shown the excellent capacity of ILs containing thiocyanate or dicyanamide anions to enhance the solubility of artemisinin in aqueous media, with a magnitude comparable to that obtained with the best organic solvents. Furthermore, solvatochromic parameters of the ILs aqueous solutions were also measured and combined with COSMO-RS and the cooperative hydrotropy model to establish relations between the artemisinin solubility enhancement and the solvent characteristics. The solubility enhancement of artemisinin is favored by the apolarity of the medium and the lower hydrogen-bond acceptor character of the hydrotrope.This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, CIMO-Mountain Research Center, UIDB/00690/2020, all financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. Isabela Sales and Silvana Mattedi thanks the finantial support from CAPES and CNPq/Brazil (CAPES: Proc. 88881.189075/2018-01 and 88887.494428/2020-00. CNPq: Grant 303089/2019-9 and Proc.438036/2018-2).info:eu-repo/semantics/publishedVersio
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