The evaluation of phenolic content, in vitro antioxidant and antibacterial activity of Mentha piperita extracts obtained by natural deep eutectic solvents

Recovery of Cembratrien-Diols from Waste Tobacco (Nicotiana tabacum L.) Flowers by Microwave-Assisted Deep Eutectic Solvent Extraction: Optimization, Separation, and In Vitro Bioactivity

Deep eutectic solvents (DESs) are novel solvents with physicochemical properties similar to those of ionic liquids, and they have attracted extensive attention for the extraction of bioactive compounds from different plant materials in the context of green chemistry and sustainable development. In this study, seven DESs with different polarities were explored as green extraction solvents for cembratrien-diols (CBT-diols) from waste tobacco flowers. The best solvent, DES-3 (choline chloride: lactic acid (1:3)), which outperformed conventional solvents (methanol, ethanol, and ethyl acetate), was selected and further optimized for microwave-assisted DES extraction using the response surface methodology. The maximum yield of CBT-diols (6.23 ± 0.15 mg/g) was achieved using a microwave power of 425 W, microwave time of 32 min, solid/liquid ratio of 20 mg/mL, and microwave temperature of 40 °C. Additionally, the isolated CBT-diols exhibited strong antimicrobial activity against Salmonella, Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa and antitumor activity in the human liver cancer HepG2 and SMMC-7721 cell lines. This study highlights the feasibility of recovering CBT-diols from tobacco flower waste using DESs and provides opportunities for potential waste management using green technologies.

Current situation, trend, and prospects of research on functional components from by-products of baijiu production: A review

In the present scenario marked by energy source shortages and escalating concerns regarding carbon dioxide emissions, there is a growing emphasis on the optimal utilization of biomass resources. Baijiu, as the Chinese national spirit, boasts remarkably high sales volumes annually. However, the production of baijiu yields various by-products, including solid residues (Jiuzao), liquid wastewater (Huangshui and waste alcohol), and gaseous waste. Recent years have witnessed dedicated research aimed at exploring the composition and potential applications of these by-products, seeking sustainable development and comprehensive resource utilization. This review systematically summarizes recent research, shedding light on both the baijiu brewing process and the bioactive compounds present baijiu production by-products (BPBPs). The primary focus lies in elucidating the potential extraction methods and applications of BPBPs, offering a practical approach to comprehensive utilization of by-products in functional food, medicine, cosmetic, and packaging fields. These applications not only contribute to enhancing production efficiency and mitigating environmental pollution, but also introduce innovative concepts for the sustainable advancement of associated industries. Future research avenues may include more in-depth compositional analysis, the development of utilization technologies, and the promotion of potential industrialization.

Lavandula pedunculata Polyphenol-Rich Extracts Obtained by Conventional, MAE and UAE Methods: Exploring the Bioactive Potential and Safety for Use a Medicine Plant as Food and Nutraceutical Ingredient

Nowadays, plant-based bioactive compounds (BCs) are a key focus of research, supporting sustainable food production and favored by consumers for their perceived safety and health advantages over synthetic options. Lavandula pedunculata (LP) is a Portuguese, native species relevant to the bioeconomy that can be useful as a source of natural BCs, mainly phenolic compounds. This study compared LP polyphenol-rich extracts from conventional maceration extraction (CE), microwave and ultrasound-assisted extraction (MAE and UAE). As a result, rosmarinic acid (58.68-48.27 mg/g DE) and salvianolic acid B (43.19-40.09 mg/g DE) were the most representative phenolic compounds in the LP extracts. The three methods exhibited high antioxidant activity, highlighting the ORAC (1306.0 to 1765.5 mg Trolox equivalents (TE)/g DE) results. In addition, the extracts obtained with MAE and CE showed outstanding growth inhibition for B. cereus, S. aureus, E. coli, S. enterica and P. aeruginosa (>50%, at 10 mg/mL). The MAE extract showed the lowest IC50 (0.98 mg DE/mL) for angiotensin-converting enzyme inhibition and the best results for α-glucosidase and tyrosinase inhibition (at 5 mg/mL, the inhibition was 87 and 73%, respectively). The LP polyphenol-rich extracts were also safe on caco-2 intestinal cells, and no mutagenicity was detected. The UAE had lower efficiency in obtaining LP polyphenol-rich extracts. MAE equaled CE's efficiency, saving time and energy. LP shows potential as a sustainable raw material, allowing diverse extraction methods to safely develop health-promoting food and nutraceutical ingredients.

Neutral natural deep eutectic solvents as anti-biofilm agents

Natural deep eutectic solvents (NADES) are a class of liquids with promising properties as components in pharmaceutical formulations, such as a low toxicity profile, biodegradability and versatility. Recently, their potential use as anti-biofilm agents has been proposed, due to their ability to solubilize and stabilize biological macromolecules. In the current work, the ability to break down biofilm matrix and the biofilm killing activity of three NADES of neutral pH were investigated against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 9027 biofilms. The tested NADES were choline chloride:xylitol (ChX), choline chloride:glycerol (ChG) and betaine:sucrose (BS). Two of the NADES (ChX and ChG) significantly reduced the number of remaining viable cells of both bacterial species in pre-formed biofilm by 4-6 orders of magnitude, while the average biofilm biomass removal for all NADES was 27-67% (S. aureus) and 34-49% (P. aeruginosa). The tested NADES also inhibited biofilm formation of both bacterial species at concentrations at or below 0.5 x the minimal inhibitory concentration (MIC), possibly in part due to observed restrictions imposed by NADES on planktonic growth. These results demonstrate the potential value of neutral NADES as anti-biofilm agents in future antimicrobial preparations.

Deep Eutectic Solvents Based on Carboxylic Acids and Glycerol or Propylene Glycol as Green Media for Extraction of Bioactive Substances from Chamaenerion angustifolium (L.) Scop

Chamaenerion angustifolium (L.) Scop. is one of the promising sources of biologically active compounds and a valuable industrial crop. Recently, green extraction methods have become more topical. One of them is the application of deep eutectic solvents (DESs). The aim of this work was the synthesis and characterization of DES consisting of glycerin or propylene glycol with malonic, malic, or citric acids, evaluation of their effectiveness for extracting useful substances from C. angustifolium during ultrasonic extraction, description of kinetics, and optimization of extraction conditions. DESs were obtained and characterized with FTIR. Their effectiveness in the process of ultrasound-assisted extraction of biologically active substances from C. angustifolium was estimated. Kinetic parameters describing the dependence of the total phenolic, flavonoids, and antioxidant content, free radical scavenging of DPPH, and concentration of flavonoid aglycons (myricetin, quercetin, and kaempferol) via time in the range of 5-60 min at 45 °C are obtained. Extraction conditions were optimized with the Box-Behnken design of experiment. The results of this work make it possible to expand the scope of DES applications and serve the development of C. angustifolium processing methods.

The increasing importance of novel deep eutectic solvents as potential effective antimicrobials and other medicinal properties

With the rise of antibiotic resistance globally, coupled with evolving and emerging infectious diseases, there is an urgent need for the development of novel antimicrobials. Deep eutectic solvents (DES) are a new generation of eutectic mixtures that depict promising attributes with several biological implications. DES exhibit unique properties such as low toxicity, biodegradability, and high thermal stability. Herein, the antimicrobial properties of DES and their mechanisms of action against a range of microorganisms, including bacteria, amoebae, fungi, viruses, and anti-cancer properties are reviewed. Overall, DES represent a promising class of novel antimicrobial agents as well as possessing other important biological attributes, however, future studies on DES are needed to investigate their underlying antimicrobial mechanism, as well as their in vivo effects, for use in the clinic and public at large.

Evaluating the Effect of pH, Temperature and Concentration on Antioxidant and Antibacterial Potential of Spectroscopically, Spectrophotometrically and Microscopically Characterized Mentha Spicata Capped Silver Nanoparticles

The use of traditional plants has been tremendously increased due to their higher biological impact, minimal side effects, and comparatively low cost. Moreover, the emergence of antibacterial resistance is also shifting the scientific community to reconsider herbal remedies which provide relatively safer, cheap and biologically tolerable solutions. The present research was designed to fabricate the Mentha spicata conjugated silver nanoparticles (Me-AgNPs). Furthermore, the assessment of the bactericidal potential of Me-AgNPs against various bacterial strains was another motive behind this study. Fabricated NPs were characterized with the help of the UV-Visible spectrophotometric analysis, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). Me-AgNPs showed a significant zone of inhibition (23 ± 0.2 mm) at 8 mg/mL against Staphylococcus aureus and a 4.0 ± 0.2 mm zone of growth inhibition at 2 mg/mL against Aeromonas veronii. The stability of Me-AgNPs was assessed at various pH (4, 7 and 11) and temperatures (25 °C, 4 °C, 37 °C, 75 °C). The significant zones of inhibition (11.3 ± 0.3 mm, 8.3 ± 0.3mm, 14.3 ± 0.3 mm, and 7.6 ± 0.2 mm) were observed at pH 11 against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Klebsiella pneumoniae, respectively. Growth inhibition zones (14.0 ± 0.5 mm and 13.0 ± 0.5 mm) were also determined against B. subtilis and S. aureus at 25 °C. DPPH bioassay was conducted to find the antioxidant properties of Me-AgNPs. The highest (38.66 ± 0.2%) free radical scavenging activity was shown by Me-AgNPs at 4 mg/mL. Present study results concluded that biogenic Me-AgNPs have bactericidal as well as anti-oxidative potential. Moreover, these green synthesized Me-AgNPs could maintain their potency and stability at a wide range of pH and temperature.

The Most Potent Natural Pharmaceuticals, Cosmetics, and Food Ingredients Isolated from Plants with Deep Eutectic Solvents

There is growing interest in reducing the number of synthetic products or additives and replacing them with natural ones. The pharmaceutical, cosmetic, and food industries are especially focused on natural and bioactive chemicals isolated from plants or microorganisms. The main challenge here is to develop efficient and ecological methods for their isolation. According to the strategies and rules of sustainable development and green chemistry, green solvents and environmentally friendly technologies must be used. The application of deep eutectic solvents as efficient and biodegradable solvents seems to be a promising alternative to traditional methods. They are classified as being green and ecological but, most importantly, very efficient extraction media compared to organic solvents. The aim of this review is to present the recent findings on green extraction, as well as the biological activities and the possible applications of natural plant ingredients, namely, phenolics, flavonoids, terpenes, saponins, and some others. This paper thoroughly reviews modern, ecological, and efficient extraction methods with the use of deep eutectic solvents (DESs). The newest findings, as well as the factors influencing the efficiency of extraction, such as water content, and hydrogen bond donor and acceptor types, as well as the extraction systems, are also discussed. New solutions to the major problem of separating DESs from the extract and for solvent recycling are also presented.

Ionic liquid as hydrogen bond acceptor in the extraction of nutritional natural products

In-depth studies of the extraction mechanism using deep eutectic solvents (DES), especially extraction through the formation of a deep eutectic system (DESys), revealed commonalities between the DES- and ionic liquids (IL)-based extraction systems. New applications of ILs and DES for extraction of nutritional natural products were presented. In this study, the extraction behavior of choline chloride (ChCl) and 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HMIm][Cl]) in DES and IL, respectively, in mechanochemical extraction of target compounds from Moringa oleifera leaves was systematically studied. The results suggested that both extraction methods were based on the formation of a DESys, either a normal DESys or an IL DESys. Considering the DESys-based one-step extraction improves the extraction efficiency and reduces the preparation time, the same idea can be used in IL for performance improvement. By formation of a new IL deep eutectic system based on hydrogen bond interaction in extraction, similar improvement was obtained.

Phenolic metabolites as therapeutic in inflammation and neoplasms: molecular pathways explaining their efficacy

Polyphenols, also known as phenolic compounds, are chemical substances containing aromatic rings as well as at least two hydroxyl groups. Natural phenolic compounds exist widely in plants, which protect plants from ultraviolet radiation and other insults. Phenolic compounds have superior pharmacological and nutritional properties (antimicrobial, antibacterial, antiviral, anti-sclerosis, antioxidant, and anti-inflammatory activities), which have been paid more and more attention by the scientific community. Phenols can protect key cellular components from reactive free radical damage, which is mainly due to their property to activate antioxidant enzymes and alleviate oxidative stress and inflammation. It can also inhibit or isolate reactive oxygen species and transfer electrons to free radicals, thereby avoiding cell damage. It has a regulatory role in glucose metabolism, which has a promising prospect in the prevention and intervention of diabetes. It also prevents cardiovascular disease by regulating blood pressure and blood lipids. Polyphenols can inhibit cell proliferation by affecting Erk1/2, CDK, and PI3K/Akt signaling pathways. Polyphenols can function as enhancers of intrinsic defense systems, including superoxide dismutase (SOD) and glutathione peroxidase (GPX). Simultaneously, they can modulate multiple proteins and transcription factors, making them promising candidates in the investigation of anti-cancer medications. This review focuses on multiple aspects of phenolic substances, including their natural origins, production process, disinfection activity, oxidative and anti-inflammatory functions, and the effects of different phenolic substances on tumors.

NADES blend for bioactive coating design as a sustainable strategy for postharvest control

Bioactive functional coatings constitute a trendy topic due to they reduce postharvest fruit losses worldwide. Also, they could be carriers of biocompounds providing health benefits to the consumer. In this work, an innovative natural bioactive coating based on Natural Deep Eutectic Solvents (NADES) and Larrea divaricata extract was optimized by mixture-mixture design for the management of postharvest diseases caused by Monilinia fructicola. A NADES composed of lactic acid-glucose-water (LGH) for phenolic extraction from L. divaricata was optimized by a Simplex Lattice design and response surface methodology (RSM).Then, a d-optimal mixture-mixture design was carried out in order to optimize the bioactive coating composition, being the optimal proportion of 0.7 L. divaricata-LGH extract and 0.3 NADES plasticizer (composed by glycerol, citric acid and water). The optimal biocoating achieved an in vitro antimicrobial activity of 72 % against M. fructicola. Interestingly, NADES plasticizer improves the biocoating functionality, creating a smooth and uniform surface.

Non-thermal plasma modulation of the interaction between whey protein isolate and ginsenoside Rg1 to improve the rheological and oxidative properties of emulsion

Molecular interaction forces regulate the interfacial properties of oil-in-water emulsion and play a key role in the rheology and stability of the emulsion in the food industry. In this study, the effects of non-thermal plasma (NTP) treatment on the structural and functional properties of whey protein isolate (WPI) and its binding interaction with ginsenoside Rg₁ (GR₁) were investigated. The results based on surface hydrophobicity, infrared spectroscopy and fluorescence spectroscopy test showed that the NTP treatment induced the unfolding of the structure of WPI and promoted the binding affinity between WPI and GR₁. By comparing with untreated WPI (an α-helix content of 19.63 % and a β-sheet content of 31.66 %), there was a greater decrease in α-helix content and an increase in β-sheet content of WPI in N₂₀-WPI (α-helix = 9.63 %, β-sheet = 39.63 %) and N₂₀-WPI-GR₁ (α-helix = 4.98 %, β-sheet = 48.66 %) groups. Importantly, the NTP treatment increased the interfacial adsorption and antioxidant capacity of the WPI-GR1 complexes, which contributed to the improvement of the rheological properties and oxidation stability of the emulsion. As a result, the NTP treatment could markedly improve the rheological and antioxidative properties of the WPI-GR₁ complexes and the NTP-treated WPI-GR₁ emulsions was more stable than that untreated. The present research indicated that NTP-treated formation of protein-saponin complexes could enhance the functional properties of the proteins, thus expanding their application as functional ingradients in nutritionally fortified food.

Antimicrobial Activity of Novel Deep Eutectic Solvents

Herein, we utilized several deep eutectic solvents (DES) that were based on hydrogen donors and hydrogen acceptors for their antibacterial application. These DES were tested for their bactericidal activities against Gram-positive (Streptococcus pyogenes, Bacillus cereus, Streptococcus pneumoniae, and methicillin-resistant Staphylococcus aureus) and Gram-negative (Escherichia coli K1, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Serratia marcescens) bacteria. Using lactate dehydrogenase assays, DES were evaluated for their cytopathic effects towards human cells. Results from antibacterial tests revealed that DES prepared from the combination of methyl-trioctylammonium chloride and glycerol (DES-4) and DES prepared form methyl-trioctylammonium chloride and fructose (DES-11) at a 2 µL dose showed broad-spectrum antibacterial behavior and had the highest bactericidal activity. Moreover, DES-4 showed 40% and 68% antibacterial activity against P. aeruginosa and E. coli K1, respectively. Similarly, DES-11 eliminated 65% and 61% E. coli K1 and P. aeruginosa, respectively. Among Gram-positive bacteria, DES-4 showed important antibacterial activity, inhibiting 75% of B. cereus and 51% of S. pneumoniae. Likewise, DES-11 depicted 70% B. cereus and 50% S. pneumoniae bactericidal effects. Finally, the DES showed limited cytotoxic properties against human cell lines with the exception of the DES prepared from Methyltrioctylammonium chloride and Citric acid (DES-10), which had 88% cytotoxic effects. These findings suggest that DES depict potent antibacterial efficacies and cause minimal damage to human cells. It can be concluded that the selected DES in this study could be utilized as valuable and novel antibacterial drugs against bacterial infections. In future work, the mechanisms for bactericides and the cytotoxicity effects of these DES will be investigated.

Ultrasound-Assisted Deep Eutectic Solvent Extraction of Polysaccharides from Anji White Tea: Characterization and Comparison with the Conventional Method

Deep eutectic solvent as a new green and safe solvent system has attracted more and more attention in recent years. In this study, three deep eutectic solvents (DES) were combined with ultrasound irradiation to extract tea polysaccharides (TPs) from Anji white tea, which was compared with conventional hot water extraction (HW). The physicochemical, structural, and biological properties of TPs extracted by ultrasound-assisted DES and hot water (HWP) were further investigated. Results showed that the DES system composed of choline chloride and 1,6-hexanediol (CH) with the molar ratio of 1:2 exhibited the optimal extraction yield (19.18%) and in vitro antioxidant activities for TPs (CHP). Furthermore, compared to the HWP, the CHP had a higher extraction yield and total carbohydrate content and a lower molecular weight. Monosaccharide composition analysis displayed that the molecular structure of CHP exhibited more arabinose but less glucose, mannose, galacturonic acid, and glucuronic acid than HWP. Little difference was observed in the preliminary structural characteristics between HWP and CHP from Fourier transform infrared analysis. Besides, CHP possessed better α-glucosidase inhibitory and hypoglycemic activity in L6 cells than HWP. Therefore, the ultrasound-assisted DES extraction method can be a promising strategy for extracting TPs with excellent bioactivities for future applications in functional foods.

Technique for order preference by similarity to ideal solution (TOPSIS): a MCDM approach for selecting suitable solvent considering biochemical profiles and in vitro antibacterial efficacy of petioles of betel leaf (Piper betle L.)

Petioles of betel leaf (BLP) are the major industrial by-products of betel leaf industries sold at throwaway prices or used as cattle feed. The present work was taken up to evaluate suitable solvent based on yield, antioxidant, and antimicrobial properties to isolate extract of BLP using the Shannon entropy-TOPSIS method. Four solvents were chosen for the extraction process: hexane, toluene + ethanol (2:1), acetone, and ethanol. The findings showed that ethanol-based BLP extract had the highest TPC value, measuring 2193.71 ± 0.17 mg of gallic acid equivalence/g of dry extract, while acetone-based extracts had the highest TFC value, measuring 8.03 mg of quercetin equivalent/g of dry extract. Radical scavenging activities like DPPH (IC₅₀ = 52.44 μg/mL), ABTS (IC₅₀ = 62.41 μg/mL), and FRAP (8.03 mg QE/g of dry extract) were found best for acetone extract. The antibacterial study of the extracts revealed that acetone extract was more sensitive to Gram-positive and Gram-negative bacterial strains followed by ethanol, toluene + ethanol, and hexane extracts. Among five foodborne bacteria, B. subtilis showed the highest susceptibility against all extracts. GC-MS analysis showed that acetoxychavicol acetate (31.27%) (PubChem ID: 119,104), germacrene D (7.24%) (PubChem Id: 531,750), isoxylic acid (22.56%) (PubChem ID: 11,892), and cis-1,2-indandiol (43.92%) (PubChem ID: 20,758) are four major compounds among 22 components. TOPSIS analysis revealed that acetone extract had the highest relative closeness value (0.71) followed by ethanol (0.65), toluene + ethanol (0.53), and hexane (0.32). These results indicate that acetone extract of BLP can be considered an alternative to synthetic active ingredients in the future. These results indicated that TOPSIS method has computational robustness for selecting a solvent comparing yield, antioxidant, and antimicrobial activities of extract of a plant part.

Effective extraction of bioactive alkaloids from the roots of Stephania tetrandra by deep eutectic solvents-based ultrasound-assisted extraction

The efficient and green extraction of bioactive ingredients from natural plants play a vital role in their corresponding drug effects and subsequent studies. Recently, deep eutectic solvents (DESs) have been considered promising new green solvents for efficiently and selectively extracting substances from varied plants. In this work, an environment-friendly DESs-based ultrasonic-assisted extraction (DESs-UAE) procedure was developed for highly efficient and non-polluting extraction of alkaloids from the roots of Stephania tetrandra (ST). A total of fifteen different combinations of DESs, compared with traditional organic solvents (methanol and 95% ethanol) and water, were evaluated for extraction of bioactive alkaloids (FAN and TET) from ST, and the results revealed that DESs system made up of choline chloride and ethylene glycol with mole ratio of 1:2 exhibited the optimal extraction efficiency for alkaloids. Additionally, a four-factor and three-level Box-Behnken design (BBD), a particular pattern of response surface methodology (RSM), was used to optimize extraction conditions. RSM results indicated that the maximum extraction yields of FAN, TET, and TA were attained 7.23, 13.36, 20.59 mg/g, respectively, within extraction temperature of 52 °C, extraction time of 82 min, DES water content of 23% (v/v), and liquid-solid ratio of 23 mL/g. The measured results were consistent with the predicted values. Notably, the optimized DES extraction efficiency of TA, according to the experimental data analysis, is 2.2, 3.3 and 4.1 times higher than methanol, 95% ethanol and water, respectively. Meanwhile, based on 3D response surface plots, interactive effects plots and contour maps, the effects of the aforementioned four essential factors on the extraction yield and their interactions on the response were visualized. The results revealed that the mutual interactions between extraction temperature and liquid-solid ratio exhibited positive effects on all responses, while extraction time and water content in DES posed a negative effect. Therefore, these results suggest that DESs, as a class of novel green solvents, with the potential to substitute organic solvent and water, can be widely and effectively applied to extract bioactive compounds from natural plants.

Detoxification of comfrey (Symphytum officinale L.) extract using natural deep eutectic solvent (NADES) and evaluation of its anti-inflammatory, antioxidant, and hepatoprotective properties

Comfrey (Symphytum officinale L.) contains rosmarinic acid which has different pharmacological activities, such as antioxidant and anti-inflammatory activities. However, the medicinal use of comfrey is limited by the hepatotoxic effect of lycopsamine in comfrey, which overshadows the health benefits of rosmarinic acid. Natural deep eutectic solvents (NADES) have a wide range of extraction properties, that provides a new approach to the detoxification of comfrey. In the present study, betaine-based and choline chloride-based NADES were screened for selective extraction of rosmarinic acid over lycopsamine. Ultrasonication was used in conjunction with NADES extraction. The chemical profile of the NADES extracts on antioxidant, anti-inflammatory and hepatotoxic activities were investigated using some chemical reagents. Betaine-urea (1:2 molar ratio, 50% water) obtained the highest content of rosmarinic acid and a low level of lycopsamine (1.934 and 0.018 mg/g, respectively). Betaine-urea was also shown to be more effective to extract rosmarinic acid compared to methanol-UAE under the same conditions, which gave lower rosmarinic acid and higher lycopsamine levels (0.007 and 0.031 mg/g, respectively). Betaine-urea extracts showed higher antioxidant and anti-inflammatory properties as compared with other NADES extracts, however, had lower hepatotoxic profile. This study recommends the use of betaine-urea to detroxify comfrey to open wider opportunities for the development of comfrey for medicinal use.

Solubility of Rosmarinic Acid in Supercritical Carbon Dioxide Extraction from Orthosiphon stamineus Leaves

Rosmarinic acid (RA) is present in a broad variety of plants, including those in the Lamiaceae family, and has a wide range of pharmacological effects, particularly antioxidant activity. To extract RA from Orthosiphon stamineus (OS) leaves, a Lamiaceae plant, a suitable extraction process is necessary. The present study used a green extraction method of supercritical carbon dioxide (SCCO2) extraction with the addition of ethanol as a modifier to objectively measure and correlate the solubility of RA from OS leaves. The solubility of RA in SCCO2 was determined using a dynamic extraction approach, and the solubility data were correlated using three density-based semi-empirical models developed by Chrastil, del Valle-Aguilera, and Gonzalez. Temperatures of 40, 60, and 80 °C and pressures of 10, 20, and 30 MPa were used in the experiments. The maximum RA solubility was found at 80 °C and 10 MPa with 2.004 mg of rosmarinic acid/L solvent. The RA solubility data correlated strongly with the three semi-empirical models with less than 10% AARD. Furthermore, the fastest RA extraction rate of 0.0061 mg/g min−1 was recorded at 80 °C and 10 MPa, and the correlation using the Patricelli model was in strong agreement with experimental results with less than 15% AARD.

Extraction of Bioactive Metabolites from Achillea millefolium L. with Choline Chloride Based Natural Deep Eutectic Solvents: A Study of the Antioxidant and Antimicrobial Activity

In this study, the extraction efficiency of natural deep eutectic solvents (NADES) based on choline chloride as a hydrogen bond acceptor (HBA) and five different hydrogen bond donors (HBD; lactic acid, 1,4-butanediol, 1,2-propanediol, fructose and urea) was evaluated for the first time for the isolation of valuable bioactive compounds from Achillea millefolium L. The phytochemical profiles of NADES extracts obtained after ultrasound-assisted extraction were evaluated both spectrophotometrically (total phenolic content (TPC) and antioxidant assays) and chromatographically (UHPLC-MS and HPLC-UV). The results were compared with those obtained with 80% ethanol, 80% methanol, and water. The highest TPC value was found in the lactic acid-based NADES (ChCl-LA), which correlated with the highest antioxidant activity determined by the FRAP analysis. On the other hand, the highest antiradical potential against ABTS+• was determined for urea-based NADES. Phenolic acids (chlorogenic acid and dicaffeoylquinic acid isomers), flavones (luteolin and apigenin), and their corresponding glucosides were determined as the dominant individual phenolic compounds in all extracts. The antibacterial and antifungal properties of the extracts obtained against four bacterial cultures and two yeasts were evaluated using two methods: the agar dilution method to obtain the minimum inhibitory concentration (MIC) and the minimum bactericidal or fungicidal concentration (MBC or MFC), and the disc diffusion method. ChCl-LA had the lowest MIC and MBC/MFC with respect to all microorganisms, with an MIC ranging from 0.05 mg mL−1 to 0.8 mg mL−1, while the water extract had the weakest inhibitory activity with MIC and MBC/MFC higher than 3.2 mg mL−1.

The ability of deep eutectic solvent systems to extract bioactive compounds from apple pomace

The objective of this study was to examine the bioactivity of extracts from apple pomace obtained by non-conventional green extraction methods (DES systems). Bioactivity was antioxidant capacity and ability to stimulate insulin secretion from pancreatic beta-cells. The antioxidant capacity of extracts was examined using the DPPH and the FRAP assay. Impact of the extracts on cell viability and insulin secretion were examined using the BRIN-BD11 cell line. ChCl:EG(1:4) extracts resulted in high antioxidant capacity in the DPPH assay (80.1% inhibition versus 11.3%). Extracts obtained from the classical systems demonstrated an ability to promote insulin secretion significantly higher than the positive control, p < 0.05. ChCl:EG(1:4) extracts stimulated insulin secretion to a lesser extent. Overall, the data provides evidence for the potential of DES systems to extract bioactive compounds from apple pomace that have relevance for metabolic health. Further optimisation of the extraction procedures should be tailored to the desired bioactive properties.

Novel Perceptions on Chemical Profile and Biopharmaceutical Properties of Mentha spicata Extracts: Adding Missing Pieces to the Scientific Puzzle

Mentha spicata is one of the most popular species in the genus, and it is of great interest as a gastrointestinal and sedative agent in the folk medicine system. In this study, different M. spicata extracts, obtained by the use of four solvents (hexane, chloroform, acetone and acetone/water) were chemically characterized using HPLC-ESI-MS n, which allowed for identification of 27 phenolic compounds. The extracts' antioxidant and enzyme inhibitory properties were investigated. In addition, neuroprotective effects were evaluated in hypothalamic HypoE22 cells, and the ability of the extracts to prevent the hydrogen peroxide-induced degradation of dopamine and serotonin was observed. The best antioxidant effect was achieved for all the extraction methods using acetone/water as a solvent. These extracts were the richest in acacetin, eriodictyol, hesperidin, sagerinic acid, naringenin, luteolin, chlorogenic acid, chrysoeriol and apigenin. The intrinsic antioxidant and enzyme inhibition properties of the acetone/water extract could also explain, albeit partially, its efficacy in preventing prostaglandin E2 overproduction and dopamine depletion (82.9% turnover reduction) in HypoE22 cells exposed to hydrogen peroxide. Thus, our observations can provide a scientific confirmation of the neuromodulatory and neuroprotective effects of M. spicata.

Chemical compositions and bioactivities of essential oil from perilla leaf (Perillae Folium) obtained by ultrasonic-assisted hydro-distillation with natural deep eutectic solvents

Natural deep eutectic solvents (NADESs) have received considerable attention for green extraction. In this study, ultrasonic-assisted natural deep eutectics were applied for hydrodistillation to extract essential oil from perilla leaves. Compared to hydrodistillation assisted with ultrasound, this novel method effectively raised the yield of perilla leaf EO from 0.21% to 0.69% (choline chloride: malic acid, molar ratio 2:1) and broadened the types of chemical compositions (71 in total), especially aliphatic and aromatic compounds. Stronger antimicrobial and antioxidant activity was confirmed, and phenolics were increased. Additionally, the pH of the final solution was detected. The leaf residues were dried, weighed and analyzed by scanning electron microscopy to show the influence of NADESs' strong extractability. This new extraction method may be applicable in edible natural product extraction and provide a reference for further exploration of NADESs.

Customized Deep Eutectic Solvents as Green Extractants for Ultrasonic-Assisted Enhanced Extraction of Phenolic Antioxidants from Dogbane Leaf-Tea

This study evaluates the application of eco-friendly deep eutectic solvents (DESs) in the extraction of phenolic antioxidants from dogbane leaf-tea (DLT). The results showed DESs with lower viscosity allowed an efficient extraction of significantly higher contents of total phenolics or flavonoids. An innovative and high-efficient solvent, choline chloride-levulinic acid (ChCl-LevA), was screened and used in ultrasonic-assisted extraction (UAE) of phenolic compounds from DLT. According to full factorial design experimental results, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity, and anti-α-glucosidase activity (α-GIA) of the DLT extracts were simultaneously optimized by response surface methodology. Sonication temperature and water content in ChCl-LevA were found to be the major factors affecting the TPC, TFC, antioxidant activity, and α-GIA of DLT extracts. Under the optimum parameters (water content in ChCl-LevA was 45%, sonication temperature was 50 °C, and extraction time was 30 min), the measured results for all the responses were obtained as follows: TPC-91.38 ± 7.20 mg GAE/g DW, TFC-84.12 ± 3.47 mg RE/g DW, ABTS⁺-492 ± 7.33 mmol TE/g DW, FRAP-6235 ± 121 μmol Fe(II)/g DW and α-GIA-230 ± 7.59 mmol AE/g DW, which were consistent with the predicted values. In addition, strongly significant positive correlations were observed between TPC/TFC and bio-activities of the DLT extracts. HPLC results indicated high contents of (-)-epigallocatechin (4272 ± 84.86 μg/g DW), catechin (5268 ± 24.53 μg/g DW), isoquercitrin (3500 ± 86.07 μg/g DW), kaempferol 3-O-rutinoside (3717 ± 97.71 μg/g DW), and protocatechuic acid (644 ± 1.65 μg/g DW) were observed in the DLT extracts. In contrast to other extraction methods, ChCl-LevA-based UAE yielded higher TPC, TFC, individual phenolic contents, stronger antioxidant activity, and α-GIA. Scanning electron microscope (SEM) analysis further confirmed that ChCl-LevA-based UAE enhanced the disruption of cell wall structure, thereby making more phenolic antioxidants released from DLT. In short, ChCl-LevA-based UAE was confirmed to be an innovative and high-efficient method for extraction of phenolic antioxidants from DLT. Dogbane leaves can be considered as a good tea source rich in natural antioxidants.

Natural Deep Eutectic Solvents (NADES): Phytochemical Extraction Performance Enhancer for Pharmaceutical and Nutraceutical Product Development

Natural products from plants were extracted and widely studied for their activities against many disease conditions. The selection of the extracting solvent is crucial to develop selective and effective methods for the extraction and isolation of target compounds in the plant matrices. Pharmacological properties of plant extracts and their bioactive principles are related to their excellent solubility, stability, and bioavailability when administered by different routes. This review aims to critically analyze natural deep eutectic solvents (NADES) as green solvents in their application to improve the extraction performance of plant metabolites in terms of their extractability besides the stability, bioactivity, solubility, and bioavailability. Herein, the opportunities for NADES to be used in pharmaceutical formulations development including plant metabolites-based nutraceuticals are discussed.

COSMOtherm as an Effective Tool for Selection of Deep Eutectic Solvents Based Ready-To-Use Extracts from Graševina Grape Pomace

The aim of this work is to develop an industrially suitable process for the sustainable waste disposal in wine production. The proposed process involves the development of an environmentally friendly method for the isolation of biologically active compounds from Graševina grape pomace according to the green extraction principles, in order to obtain a ready-to-use extract. In this process, deep eutectic solvents (DES) were used as extraction solvents. Aiming to save time in selecting the optimal DES that would provide the most efficient Graševina pomace polyphenols extraction, the user-friendly software COSMOtherm was used and 45 DES were screened. Moreover, the prepared extracts were chemically and biologically characterized to confirm their safety for human application. Computational and experimental results proved the applicability of COSMOtherm in the selection of the optimal DES for the environmentally friendly preparation of the ready-to-use extract from Graševina grape pomace with expected application in the cosmetic industry.