Synergistic effect of probe sonication and ionic liquid for extraction of phenolic acids from oak galls

Ultrasound-Assisted Extraction of Phenolic Compounds from Celtuce (Lactuca sativa var. augustana) Leaves Using Natural Deep Eutectic Solvents (NADES): Process Optimization and Extraction Mechanism Research

Natural deep eutectic solvents (NADESs), as emerging green solvents, can efficiently extract natural products from natural resources. However, studies on the extraction of phenolic compounds from celtuce (Lactuca sativa var. augustana) leaves (CLs) by NADESs are still lacking. This study screened the NADES L-proline-lactic acid (Pr-LA), combined it with ultrasound-assisted extraction (UAE) to extract phenolic compounds from CLs, and conducted a comparative study on the extraction effect with traditional extraction solvents. Both SEM and FT-IR confirmed that Pr-LA can enhance the degree of fragmentation of cell structures and improve the extraction rate of phenolic compounds. Molecular dynamics simulation results show that Pr-LA can improve the solubility of phenolic compounds and has stronger hydrogen bonds and van der Waals interactions with phenolic compounds. Single-factor and Box-Behnken experiments optimized the process parameters for the extraction of phenolic compounds from CLs. The second-order kinetic model describes the extraction process of phenolic compounds from CLs under optimal process parameters and provides theoretical guidance for actual industrial production. This study not only provides an efficient and green method for extracting phenolic compounds from CLs but also clarifies the mechanism of improved extraction efficiency, which provides a basis for research on the NADES extraction mechanism.

Pro-inflammatory enzyme inhibition of lipoxygenases by flavonoid rich extract from Artemisia vulgaris

The peroxyl radicals generated by the activity of lipoxygenases (LOX) are mediators to trigger inflammatory diseases. Therefore, it is important to investigate potent LOX inhibitor for modulating the occurrence and resolving inflammatory processes. Artemisa vulgaris, is a herbal plant that is known for flavonoids, potentially inhibiting lipid peroxidation and scavenging radicals. The objectives of the present study were to obtain flavonoids rich extract from A. vulgaris, and determine the inhibitory mode of the extract against LOX. The flavonoids rich extract was optimized in an ultrasound assisted extraction using ionic liquids as extraction solvent. The results found that the optimum conditions; ratio of solid-to-liquid (1:10) and 30 min of extraction time could produce the high yield (10.14 %) and flavonoid content (5.30 mg QE/g). The LOX activity was demonstrated to follow a mixed mode of inhibition in the presence of the flavonoid rich extract as an inhibitor. The Michaelis-Menten constant (Km) was increased from 0.283 µM to 0.435 µM, whereas the maximum velocity was reduced from 0.22 µM/min to 0.058 µM/min in the inhibition. The flavonoids rich extract is likely to be a natural potent non-competitive inhibitor which may bind to free LOX or substrate-bound LOX.

Mechanochemical-Assisted Extraction and Biological Activity Research of Phenolic Compounds from Lotus Seedpod (Receptaculum Nelumbinis)

To explore the feasibility of the mechanochemical-assisted extraction (MCAE) of phenolic compounds from lotus seedpod (Receptaculum Nelumbinis), a single-factor experiment combined with response-surface methodology (RSM) was used to optimize the extraction process. The results showed the optimal extraction conditions as follows: Li2CO3 as a solid reagent (25%), an extraction time of 80 min, liquid/solid ratio of 42.8 mL/g, and extraction temperature of 80.7 °C; and the maximum value of total phenolic content (TPC) was 106.15 ± 1.44 gallic acid equivalents (GAE)/g dry weight (DW). Additionally, the 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) were 279.75 ± 18.71, 618.60 ± 2.70, and 634.14 ± 7.17 µmol TE/g, respectively. Ultra-high pressure liquid chromatography combined with triple-time-of-flight mass spectrophotometry (UPLC-Triple-TOF/MS) analysis identified eight phenolic compounds mainly consisting of polyphenols and flavonoids. Moreover, the phenolic compounds showed potent inhibitory effects on both α-amylase and α-glucosidase, with inhibition rates of over 80%. Furthermore, the results showed different degrees of inhibition activity against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli, among which the inhibitory effect on the growth of B. subtilis was the best. This paper shows that the phenolic compounds have good biological activities, which provides a reference for the further exploitation of LSP.

Phytochemical Profiling and Biological Activities of Quercus sp. Galls (Oak Galls): A Systematic Review of Studies Published in the Last 5 Years

Quercus species have been widely used in traditional medicine, and recently, researchers' attention has focused on galls of the genus Quercus as a source of health-promoting phytochemicals. This review presents a summary of the most recent findings on the phytochemistry and bioactivity of oak galls, following the screening of scientific papers published in two relevant databases, PubMed and Embase, between January 2018 and June 2023. The oak galls are rich in active compounds, mostly gallotannins and phenolic acids. Due to these secondary metabolites, the reviewed studies have demonstrated a wide range of biological activities, including antioxidant and anti-inflammatory actions, antimicrobial properties, tissue-protective effects, and antitumor, anti-aging, and hypoglycemic potential. Thus, oak galls are a promising natural matrix, to be considered in obtaining pharmaceutical and cosmetic preparations used in anti-aging strategies and, together with medications, in the management of age-related diseases. In further evaluations, the valuable functional properties of oak galls, reported mostly in preclinical studies, should be confirmed with clinical studies that would also take into account the potential health risks of their use.

Green extraction of Quercus infectoria gall with supercritical CO2 and methanol co-solvent

Green extraction of supercritical liquid CO2 (SCFE-CO2) using co-solvent methanol can produce a more complete phenolic acid composition and a higher quantity when compared to those without using co-solvent. The extract was devoid of toxicity. SCFE-CO2 is carried out by putting 100 g of Quercus infectoria gall of size 0.3 mm into extraction tube at temperature of 60 °C and the pressure of 20 MPa with a CO2 flow rate of 25 ml/min using co-solvent methanol with variation of flow speed 0.05, 0.5, 1.5, 3, and 6 for 60 min. The extract is analyzed using LC-MS/MS, the total phenolic content is determined using the Folin-Ceocateu method, and the toxicity value is determined using the Vero cell. According to the results, the green method of extracting SCFE-CO2 with methanol co-solvent can produce a peak and identify about 27 phenolic compounds, and increasing the rate of flow of methane co-solvent will greatly affect the outcome of the extraction to a flow rate of 0.5 ml/min, while adding a co-solvent with a flow speed above 0.5 does not affect the result. Repeated extraction of some of the largest phenolic peaks provide phenol content with minimal extract variability (div. sd. 0.1%), and the addition of soluble methanol will also increase the TPC concentration but does not increase the IC50 toxicity value above 1000.

Ionic liquids revolutionizing biomedicine: recent advances and emerging opportunities

Ionic liquids (ILs), due to their inherent structural tunability, outstanding miscibility behavior, and excellent electrochemical properties, have attracted significant research attention in the biomedical field. As the application of ILs in biomedicine is a rapidly emerging field, there is still a need for systematic analyses and summaries to further advance their development. This review presents a comprehensive survey on the utilization of ILs in the biomedical field. It specifically emphasizes the diverse structures and properties of ILs with their relevance in various biomedical applications. Subsequently, we summarize the mechanisms of ILs as potential drug candidates, exploring their effects on various organisms ranging from cell membranes to organelles, proteins, and nucleic acids. Furthermore, the application of ILs as extractants and catalysts in pharmaceutical engineering is introduced. In addition, we thoroughly review and analyze the applications of ILs in disease diagnosis and delivery systems. By offering an extensive analysis of recent research, our objective is to inspire new ideas and pathways for the design of innovative biomedical technologies based on ILs.

An efficient approach for extraction of polysaccharide from abalone (Haliotis Discus Hannai Ino) viscera by natural deep eutectic solvent

In this study, a natural deep eutectic solvent (NADES) was proposed for the ultrasonic-assisted extraction of polysaccharides from abalone (Haliotis Discus Hannai Ino) viscera. Eleven NADESs were employed for abalone viscera polysaccharide (AVP) extraction. NADES, composed of choline chloride and ethylene glycol in a molar ratio 1: 3 had the highest extraction efficiency. The optimal extraction conditions were obtained using a four-factor, three-level Box-Behnken design and specific response surface methodology. The maximum predicted polysaccharide yield was 17.32 %. Fick's second law was fitted to the extraction process of AVP by ultrasonic-assisted NADES based on a high linear correlation (R² ≥ 0.9). The extraction rate constants (k), diffusion coefficients (D_u) and half-lives (t_1/2) were calculated. Compared to the polysaccharides prepared by the conventional method, the polysaccharides extracted by NADES had a higher sugar content, lower molecular weight, more glucuronic acid, and stronger antioxidant capacity. Overall, the NADES extraction method established in this research can become a strategy for the preparation of high-purity and highly bioactive abalone viscera polysaccharides, which has implications for the exploitation and application of marine food byproduct resources.

Advances of Imidazolium Ionic Liquids for the Extraction of Phytochemicals from Plants

In this review, we present the research from 2013 to 2022 about the character of ionic liquids, the categories of phytochemicals, and the reasons for selecting imidazolium ionic liquids for phytochemical extraction. Then we introduce the structural formulae of the imidazolium ionic liquids commonly used in the extraction of phytochemicals, the methods used to prepare imidazolium ionic liquids, and a comprehensive introduction of how imidazolium ionic liquids are applied to extract phytochemicals from plants. Importantly, we discuss the strategies for studying the extraction mechanisms of imidazolium ionic liquids to extract phytochemicals, and the recovery methods regarding imidazolium ionic liquids and their recyclability are analyzed. Then the toxicity in imidazolium ionic liquids is pointed out. Finally, the challenges and prospects of extracting phytochemicals by imidazolium ionic liquids are summarized, and they are expected to provide some references for researchers.

Green synthesized fluorescent carbon dots from oak apple for detection of efavirenz

In this study, a facile synthesis of fluorescence carbon dots (CDs) from local oak apple (O-CDs) in the mountainous region of Zagros was performed through hydrothermal treatment. The characterization of O-CDs was carried out by SEM, TEM, FTIR, EDX, Mapping, lain scan, and AFM, respectively. In addition, the fluorescence of CDs was quenched by efavirenz with a linear concentration of 10 to 450 μM, associated with the limit of detection of 3 μM. Subsequently, the CDs were successfully applied for efavirenz probing in blood plasma environment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10854-023-09929-z.

Antioxidant, Cytotoxicity, Apoptotic Properties of Extracts of Andricus sternlichti galls and Their Phenolic Characterisation by HPLC

Quercus L. galls have been used in Western and Eastern cultures for various diseases in traditional medicine. Galls are also used in the East for many purposes, including consumption as food, commercial inks, leather tanning. In the current study, Andricus sternlichti Bellido, Pujade-Villar & Melika, 2003 galls were extracted in different solvents. The possible antioxidant effects of gall extracts were determined using 7 different methods (β-carotene-linoleic acid assay, Phosphomolybdenum assay, DPPH and ABTS radical scavenging activity, CUPRAC and FRAP assay, Metal Chelating activity) to support each other. Total phenolic, flavonoid and tannin amounts of extracts are calculated by using standard curves. In addition, HPLC method used to characterize the phenolic component with 15 different standards. The MIA PaCa-2 cell lines was preferred to identify possible cytotoxic activities of galls. Expression of some genes (Bax, Bcl-2, FAS, BID, caspase-3, caspase-8, caspase-9, caspase-10, FADD, TRADD) role in the apoptosis was determined to investigate apoptotic effects of extracts. According the results, the gall extracts of A. sternlichti may be considered as a potential source of biological agents for their antioxidant capacity and rich bioactive compounds. The gall extracts exhibit antiproliferative activity via regulating expressions of apoptotic genes.

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.

Recent innovations of ultrasound green technology in herbal phytochemistry: A review

Ultrasound (US) has become one of the most important techniques in green chemistry and emerging technologies. Many research investigations documented the usefulness of US in a wide range of applications in food science, nanotechnology, and complementary medicine, where effective extraction of natural products is important. However, as with all novel technologies, US has advantages and limitations that require clarification for full adaptation at an industrial scale. The present review discusses recent applications of US in herbal phytochemistry with the emphasis on US effects on chemical structures of bioactive compounds extracted from herbs and their bioactivities. The impact of different US processing conditions such as frequency, intensity, duration, temperature, and pressure on the effectiveness of the extraction process and the properties of the extracted materials are also discussed. Different frequencies and intensities of US have demonstrated its potential applications in modifying, determining, and predicting the physicochemical properties of herbs and their extracts. US has important applications in nanotechnology where it supports the fabrication of inexpensive and eco-friendly herbal nanostructures, as well as acoustic-based biosensors for chemical imaging of the herbal tissues. The application of US enhances the rates of chemical processes such as hydrolysis of herbal fibers, which reduces the time and energy consumed without affecting the quality of the final products. Overall, the use of US in herbal science has great potential to create novel chemical constructions and to be used as an innovative diagnostic system in various biomedical, food, and analytical applications.

Sonication-synergistic natural deep eutectic solvent as a green and efficient approach for extraction of phenolic compounds from peels of Carya cathayensis Sarg

An excellent high-efficiency natural deep eutectic solvent (NADES, ChCl-MA) was screened out and integrated with pulse-ultrasonication technique for extracting phenolic compounds from Carya cathayensis Sarg. peels (CCSPs). Single factor experiment combined with response surface methodology (RSM) using Box-Behnken design (BBD) were employed to investigate significant factors and optimize their influence on extraction of phenolic compounds. Significant synergistic effect triggered by ChCl-MA based pulse-ultrasonication over other methods used alone were proved by comparative study concerning a variety of bioactive components and antioxidant activities. The second-order kinetic model was developed and validated (R² > 0.99) to describe the extraction process and its mechanism; and second-order kinetic extraction rate constant (k), saturation concentration (C_s), and initial extraction rate (h) were calculated. FT-IR, DSC and SEM results further demonstrated synergistic effect and influence during extraction. Overall, this study provided a green and high-efficiency alternative for the recovery of various phenolics compounds from plant source by-products.

Oak wood drying: precipitation of crystalline ellagic acid leads to discoloration

Oak heartwood usually darkens during and after drying. This darkening can be heterogeneous, leaving noncolored areas in the wood board. These light discolorations have been linked to heterogeneous distribution of tannins, but compelling evidence on the microscale is lacking. In this study Raman and fluorescence microscopy revealed precipitations of crystalline ellagic acid, especially in the ray cells but also in lumina, cell corners and cell walls in the non-colored areas (NCA), which also had higher density. In these denser areas free water is longer present during drying and leads to accumulation of hydrolyzed tannins. When eventually falling dry, these tannins precipitate irreversible as non-colored ellagic acid and are not available for chemical reactions leading to darkening of the wood. Therefore, pronounced density fluctuations in wood boards require adjusting the drying and processing parameters so that water domains and ellagic acid precipitations are avoided during drying.

Selective extraction of bioactive compounds from plants using recent extraction techniques: A review

Plant extraction has existed for a long time and is still of interest. Due to technological improvements, it is now possible to obtain extracts with higher yields. While global yield is a major parameter because it assesses the extraction performance, it can be of interest to focus on the extraction of particular compounds (specific metabolites) to enrich the sample and to avoid the extraction of unwanted ones, for instance the primary metabolites (carbohydrates, triacylglycerols). The objective then is to improve extraction selectivity is then considered. In solid-liquid extraction, which is often called maceration, the solvent has a major impact on selectivity. Its polarity has a direct influence on the solutes extracted, related to the chemical structure of the compounds, and modelling compound/solvent interactions by using various polarity or interaction scales is a great challenge to favor the choice of the appropriate extracting liquid. Technical advances have allowed the development of recent, and sometimes green, extraction techniques, such as Microwave-Assisted Extraction (MAE), Ultrasound-Assisted Extraction (UAE), Pressurized Liquid Extraction (PLE) and Supercritical Fluid Extraction (SFE). This review focuses on the specificity of these recent techniques and the influence of their physical parameters (i.e. pressure, intensity, etc.). In addition to the solvent selection, which is of prime interest, the physical parameters applied by the different techniques influence the extraction results in different ways. Besides, SFE is a versatile and green technique suitable to achieve selectivity for some compounds. Due to its properties, SC-CO₂ allows tailoring conditions to improve the selectivity.

Antioxidant activity, phytochemical composition of Andricus tomentosus and its antiproliferative effect on Mia-Paca2 cell line

Plant derived products are widely used in cancer treatment. Gall species has been preferred for treatment various diseases in folk medicine, but there are few studies on the anticancer effects of gall species. The present study reports the antioxidant activity and total secondary metabolites of extracts of A. tomentosus galls. The antioxidant potency of galls was carried out using different in-vitro model systems. Their cytotoxic efficacy on Mia-Paca cell line was also explored. Gall extract was found to contain a large amount of phenolic acids. The extract potently scavenged free radicals including DPPH (IC₅₀ 9.56 ± 1.08 µg/mL), ABTS (IC₅₀ 18.51 ± 0.25 µg/mL). It can be seen as a potential source of antioxidants according to β-carotene/linoleic acid method (%92.58 ± 0.92) and Phosphomolybdenum assays (104.36 ± 4.95 mgAE/g). Gall extract also posses ability of metal chelating (%40.07 ± 2.30) and Fe³⁺ (184.01 ± 2.83 mgTE/g) and Cu²⁺ (89.81 ± 0.96 mgTE/g) reducing activity. According to total secondary metabolites tests, gall extract showed high total phenolic, total flavonoid and total tannin amount. HPLC analysis of the extract suggested it to contain caffeic acid (424.068.479 µg/g), ellagic acid (187.696.132 µg/g). XTT assay revealed gall extract to enhance percent survival of Mia-Paca2 cell line exposed A. tomentosus extracts. The best cytotoxic effect was determined in acetone extracts (IC₅₀: 124.7 µM). Expression of some genes (Bax, Bcl-2, FAS, BID, caspase-3, caspase-8, caspase-9, caspase-10, FADD, TRADD) in the apoptosis pathway was determined to invastigate apoptosis inducing activity. These results indicate that A. tomentosus galls possess potent antioxidant activity, when tested both in chemical as well as biological models.