Green approach to the synthesis of gold nanoparticles with antimicrobial activity using plant extracts based on a deep eutectic solvent

Banana peels, comprising about 35% of the fruit's weight, are often discarded, posing environmental and economic issues. This research focuses on recycling banana peel waste by optimizing advanced extraction techniques, specifically microwave-assisted (MAE) and ultrasound-assisted extraction (UAE), for the isolation of phenolic compounds. A choline chloride-based deep eutectic solvent (DES) with glycerol in a 1:3 ratio with a water content of 30% (w/w) was compared to 30% ethanol. Parameters, including sample-to-solvent ratio (SSR), extraction time, and temperature for MAE or amplitude for UAE, were varied. Extracts were analyzed for hydroxycinnamic acid (HCA) and flavonoid content, and antioxidant activity using FRAP and ABTS assays. DES outperformed ethanol, with HCA content ranging from 180.80 to 765.92 mg/100 g and flavonoid content from 96.70 to 531.08 mg/100 g, accompanied by higher antioxidant activity. Optimal MAE conditions with DES were an SSR of 1:50, a temperature of 60 °C, and a time of 10 min, whereas an SSR of 1:60, time of 5 min, and 75% amplitude were optimal for UAE. The polyphenolic profile of optimized extracts comprised 19 individual compounds belonging to the class of flavonols, flavan-3-ols, and phenolic acids. This study concluded that DESs, with their superior extraction efficiency and environmental benefits, are promising solvents for the extraction of high-value bioactive compounds from banana peels and offer significant potential for the food and pharmaceutical industries.

Extraction of phenolic compounds from rosemary using choline chloride – based Deep Eutectic Solvents

Effectiveness of ammonium-based deep eutectic solvents in extracting polyphenol from Chlorella vulgaris

Physicochemical properties of choline chloride-based deep eutectic solvents and excess properties of their pseudo-binary mixtures with 1-butanol

A series of deep eutectic solvents (DESs) were prepared using glycerol and choline chloride (ChCl), and Fourier transform infrared spectrometer (FT-IR) was used to analyze the spectra of glycerol, choline chloride and DESs based on glycerol and choline chloride. Then DESs were used as the additives of mobile phase to optimize chromatographic behavior of caffeic acid in high performance liquid chromatography (HPLC). A 17-run Box-Behnken design (BBD) was employed to evaluate effect of DESs as additives by analyzing the maximum theoretical plate number. Three factors, reaction temperature (60 °C, 80 °C, 100 °C), molar ratio of glycerol and choline chloride (2 : 1, 3 : 1, 4 : 1, n/n), and volume percent of additives (0.05%, 0.10%, 0.15%, v/v), were investigated in BBD. The optimum experiment condition was that of reaction temperature (80 °C), molar ratio of glycerol and ChCl (3 : 1, n/n), and volume percent of additive (0.10%, v/v). The mean chromatographic theoretical plate number of the caffeic acid this condition was 1567.5, and DESs as additives shorten the retention time and modify the chromatogram shape, proving DESs as additives for effective theoretical plate number and column efficiency in HPLC.

Choline chloride-based deep eutectic solvents (NADES): Potential use as green extraction media for polyphenols from Mentha pulegium, antioxidant activity, and antifungal activity

Choline chloride-based deep eutectic solvents in CaO-catalyzed ethanolysis of expired sunflower oil

First investigation of liposomes behavior and phospholipids organization in choline chloride-based deep eutectic solvents by atomic force microscopy

Thin Ni and Cr coatings are commonly electrodeposited from aqueous electrolytes [1,2]. These often contain series of additives, whose role is to improve the leveling and adhesion of deposited films to the substrate, decrease internal stress, and limit the hydrogen evolution reaction (HER). However, certain additives, such as thiourea as well as Cr(VI) compounds are highly hazardous [1,2]. Therefore, due to the increasing environmental awareness of the society, the electrolytes containing these constituents require replacement by green alternatives, such as Deep Eutectic Solvents (DESs).DESs, usually composed of quaternary ammonium salt and hydrogen bond donor, i.e. ethylene glycol, have wider electrochemical potential window than H2O, which in principle enables obtaining metallic coatings without the HER [3]. However, due to the low conductivity and high viscosity of DESs, it is necessary to use additives, i.e. nicotinic acid, improving these physico-chemical properties and enhancing the electrodeposition process. However, due to the unavoidable presence of water (DESs are hygroscopic), H2O can be considered an additive to DESs. The addition of H2O can be beneficial since it improves the ion mobility, and therefore increases the reduction rate [4]. The current studies focus on understanding the effect of water content on the physico-chemical properties, and the structure of DESs. However, a little is known on the influence of H2O on the electrodeposition of Ni and Cr, especially on the nucleation and growth, the effect of the morphology and chemical composition of deposited films. Therefore, an in-depth study on this topic is required.The electrolytic reduction of Ni and Cr cations in choline chloride – ethylene glycol (1ChCl:2EG) on glassy carbon and steel substrates was investigated in function of water content. This study was performed by means of electrochemical techniques, such as linear sweep voltammetry and chronoamperometry. The obtained deposits were analyzed with surface sensitive methods, i.e. scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. In order to bring the understanding on the influence of H2O as an additive on the early stage electrodeposition of Ni and Cr from DES, a combination of computational modelling with UV-vis spectroscopy was involved. This approach allowed correlating the observed electrochemical behavior of Ni and Cr cations with certain water concentrations. Establishing such relationship is of high relevance, as it may enable optimizing the process parameters for Ni and Cr electroreduction from DESs. [1] N. V. Mandich and D. L. Snyder. Modern Electroplating, chapter Electrodeposition of Chromium, pages 205–248. John Wiley & Sons, Inc., New Jersey, 5 edition, 2010.[2] G. DiBari. Modern Electroplating, chapter Electrodeposition of Nickel, pages 79-114. John Wiley & Sons, Inc., New Jersey, 5 edition, 2010.[3] E.L. Smith, A.P. Abbot, K.S. Ryder, Deep Eutectic Solvents (DESs) and Their Application, American Chemical Society Publications, 2014, pp. 11060 – 11082.[4] M. Lukaczynska, E.A. Mernissi Cherigui, A. Ceglia, K. Van den Bergh, J. De Strycker, H. Terryn, and J. Ustarroz, Influence of water content and applied potential on the electrodeposition of Ni coatings from deep eutectic solvents, Electrochimica Acta, 319: 690-704, 2019.

Tailor-made natural deep eutectic solvents for green extraction of isoflavones from chickpea (Cicer arietinum L.) sprouts

Antioxidant activity in banana peel extracts: Testing extraction conditions and related bioactive compounds

Modeling the ammonia absorption capacity of choline chloride-based deep eutectic solvents with artificial neural networks

Separation of the ethanol/water azeotropic mixture using ionic liquids and deep eutectic solvents

ABSTRACTObjective: Test the antioxidant activity of banana peel extract, watermelon rind extract, and combinations, also in lotion dosage form.Methods: The antioxidant activity of each extract and their combinations were tested with 2,2-diphenyl-1-picrylhydrazil method and formulated intoa lotion dosage forms. Evaluation of the lotion dosage forms, including organoleptic, homogeneity, pH, viscosity and rheology, microbiology, acutedermal irritation test, as well as the antioxidant activity test.Results: Antioxidant activity test on the extract showed inhibitory concentration 50% (IC50) values of banana peel is 64.03 part per million (ppm)and watermelon rind extract of 300.12 ppm. Combination of banana peel and watermelon rind extract with three different concentrations, IC50:IC50,inhibitory concentration at 75% (IC75):inhibitory concentration at 25% (IC25), IC25:IC75 resulted the best antioxidant activity is a combination of bananapeel, and watermelon rind extract IC75:IC25 with IC50 value of 177.56 ppm. The antioxidant activity test in lotion dosage form showed IC50 values oflotion base is 853.16 ppm, lotion banana peel extract is 472.50 ppm, lotion watermelon rind extract is 496.71 ppm, and the combination of bananapeel and watermelon rind extract are 300.04 ppm.Conclusion: Lotion dosage form formula that meets the requirements of quality, efficacy, and safety with the best antioxidant activity is lotion dosageform combination of banana peel and watermelon rind extract formula (IC75:IC25).Keywords: Antioxidant activity, Banana peel (Musa paradisiaca), Watermelon rind (Citrullus vulgaris), Combination of banana peel and watermelonrind extract, Lotion of antioxidant.

In this study, three different choline chloride-based deep eutectic solvents were synthesized. And it is the first time to synthesize 1,10-phenanthroline through an improved Skraup reaction using deep eutectic solvent as the new catalyst from acrolein and 8-aminoquinoline. The deep eutectic solvents were characterized by Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (1H NMR), pH/mV meter, and thermogravimetric analysis (TGA). The research results show that the deep eutectic solvent formed by sulfanilic acid and choline chloride has the strongest acidity and highest catalytic active among the three deep eutectic solvents. Besides, the impacts of reaction parameters and molar ratio of raw materials on the reaction were also investigated. Under the optimized reaction conditions, the maximum selectivity and yield of 1,10-phenanthroline were achieved as 84.6 and 75.6%, respectively. The synthesis method, meanwhile, also has simple preparation process and low cheaper catalyst raw. Replacing traditional sulfuric acid and hydrochloric acid with deep eutectic solvents (DESs) as new catalysts provides a more efficient, greener and more economical strategy for the synthesis of 1,10-phenanthroline by a new improved Skraup reaction.