Ultrasound-assisted extraction of natural antioxidants from the flower of Limonium sinuatum: Optimization and comparison with conventional methods

UPLC-MS2 Profiling of Blackthorn Flower Polyphenols Isolated by Ultrasound-Assisted Extraction

Ultrasound-assisted extraction (UAE) was optimized for fast and effective isolation of blackthorn flower polyphenols. The effects of ethanol concentration (50% and 70%) in extraction solvent, ultrasound amplitude (50%, 75%, and 100%) and extraction time (3, 6, and 9 min) were evaluated. UPLC-MS² was used to determine phenolic profile of blackthorn flowers extracts. A total of 28 different phenolic compounds were identified, belonging to the classes of hydroxycinnamic acids, flavonol glycosides and flavanols. Kaempferol and quercetin derivatives were the most abundant compounds represented by kaempferol-pentoside and rhamnoside in concentrations up to 494.94 and 436.62 mg/100 g and quercetin-pentoside in concentration up to 226.75 mg/100 g. Observed parameters of UAE did not affect the qualitative phenolic composition of blackthorn flower extracts. On the contrary, the concentration of polyphenols increased with higher ethanol concentration in solvent, higher ultrasound amplitude and prolongation of extraction time. The established conditions for optimal extraction of blackthorn flower polyphenols using ultrasound were: 70% ethanol as extraction solvent, 75% of ultrasound amplitude and 9 min extraction time, resulting in extract rich in polyphenols with a great potential for use in pharmaceutical and food industry. PRACTICAL APPLICATION: In this study, ultrasound-assisted extraction (UAE) was optimized in order to establish fast and effective method for production of crude blackthorn flower extract rich in polyphenols. UPLC-MS² analysis showed 28 different phenolic compounds belonging to the classes of hydroxycinnamic acids, flavonol glycosides, and flavanols with quercetin and kaempferol glycosides in the highest concentrations, implicating high potential of blackthorn flowers' extract for use in food and pharmaceutical industries.

Enhanced extraction of hydroxytyrosol, maslinic acid and oleanolic acid from olive pomace: Process parameters, kinetics and thermodynamics, and greenness assessment

Three techniques of ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and solvent extraction (SE) were used for enhancing the hydroxytyrosol (HT), maslinic acid (MA) and oleanolic acid (OA) extraction from olive pomace, being evaluated and compared through process parameters, kinetics and thermodynamics, plus greenness assessment analysis. Results showed that UAE yielded the maximum compounds due to a strong cavitation effect and the strongest mass and heat transfer efficiency involving the kinetic constants (h, C_e and K) and thermodynamic parameters (△H, △S and △G). Additionally, the optimal extraction conditions were acquired: ethanol concentration of 90%, extraction temperature of 50 °C, extraction time of 5 min, liquid to solid ratio of 30 mL/g, ultrasound intensity of 135.6 W/cm², and ultrasound frequency of 60 kHz. UAE was confirmed as an effective and greener technique with the lowest E factor, energy consumption and carbon emission during the extraction process of bioactive compounds from olive pomace.

Microwave-Assisted Extraction of Phenolic Compounds from Melastoma sanguineum Fruit: Optimization and Identification

A microwave-assisted extraction (MAE) technology optimized by response surface methodology (RSM) was established to extract phenolic compounds from the fruit of Melastoma sanguineum. The effects of solvent composition, ratio of solvent to material, temperature, time and microwave power on phenol yield were evaluated in single-factor tests. The three parameters exerting main impacts on phenol yield were further optimized by RSM. Under optimal extraction conditions (31.33% ethanol, solvent/material ratio of 32.21 mL/g, 52.24 °C, 45 min and 500 W), the total phenolic content was 39.02 ± 0.73 mg gallic acid equivalent (GAE)/g dry weight (DW). This MAE method performed better in comparison with two conventional methods, those being maceration (25.79 ± 1.03 mg GAE/g DW) and Soxhlet extraction (18.40 ± 1.34 mg GAE/g DW), using lower process temperature, shorter irradiation time, and lower organic solvent consumption. In addition, five flavonoids (epicatechin gallate, epicatechin, rutin, pigallocatechin and quercetin) and two phenolic acids (protocatechuic acid and chlorogenic acid) in the extract were identified and quantified using UPLC-MS/MS.

Oil removal from spent HDT catalyst by an aqueous method with assistance of ultrasound

Deoiling enjoys great significance in recycling and landfill of spent hydrotreating (HDT) catalyst. In this study, a novel approach for oil removal from spent HDT catalyst with assistance of ultrasound was developed. The effects of variables on oil removal were investigated by response surface methodology and central composite design method. The oil removal efficiency reaches 96.03 ± 0.82% under the optimum conditions of liquid-solid ratio 16.00 ml·g^-1, 75 °C, sodium hydroxide dosage 3.88 wt%, and 40 kHz ultrasonic irradiation for 3.25 h. Under the optimum conditions, the contact angle of spent catalyst is 98.7° before oil removal, and then reduces to 57.2° after deoiling with the help of ultrasound, but turns to 72° after deoiling in the absence of ultrasound, which further verifies that the oil removal efficiency can be improved by ultrasound. Compared to traditional extraction or hydrothermal methods for removing oil from spent catalyst, the proposed approach introduced ultrasonic force field to enhance oil removal efficiency without adding organic solvent or surfactant.

Optimization of ultrasonic assisted extraction of fatty acids from Aesculus hippocastanum fruit by response surface methodology

The effectiveness of ultrasound-assisted extraction (UAE) of Aesculus hippocastanum fruit oil was investigated using methanol as a solvent. The study compared extraction yields using UAE and methanol with soxhlet. The effects of three extraction parameters, namely temperature, time and the ratio of solvent (volume) to plant material (weight) were optimized using both a Box-Behnken design (BBD) and response surface methodology (RSM). The highest extraction yields were obtained for UAE at 60 °C and 56.5 min with a ratio of solvent to plant material weight of 45:1. The extraction yield using UAE varied by 21.82% (w/ w) but was, regardless, significantly greater than Soxhlet extraction.

Influence of Extraction Conditions on Ultrasound-Assisted Recovery of Bioactive Phenolics from Blueberry Pomace and Their Antioxidant Activity

The increase in diet-related chronic diseases has prompted the search for health-promoting compounds and methods to ensure their quality. Blueberry pomace is a rich yet underutilized source of bioactive polyphenols. For these high-value bioactive molecules, ultrasound-assisted extraction (USAE) is an attractive and green alternative to conventional extraction techniques for improving purity and yields. This study aimed to assess the impact of USAE parameters (sonication time, solvent composition, solid/liquid ratio, pH and temperature) on the recovery of phenolic compounds from blueberry pomace and antioxidant activity of the extracts. Total phenolic, flavonoid and anthocyanin contents (TPC, TFC and TAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity were analysed. USAE in 50% ethanol/water was the most efficient, yielding the highest TPC (22.33 mg/g dry matter (DM)), TFC (19.41 mg/g DM), TAC (31.32 mg/g DM) and DPPH radical scavenging activity (41.79 mg Trolox/g DM). USAE in water showed the lowest values even at low (1/40) solid/liquid ratio (7.85 mg/g DM, 3.49 mg/g DM, and 18.96 mg/g DM for TPC, TFC and TAC, respectively). Decreasing the solid/liquid ratio in water or 50% ethanol significantly increased TPC, TFC, TAC and DPPH radical scavenging. With ethanol, increasing the temperature in the range 20–40 °C decreased TPC but increased TFC and DPPH radical scavenging activity. Anthocyanin profiles of water and ethanolic extracts were qualitatively similar, consisting of malvidin, delphinidin, petunidin and cyanidin. These findings indicate that USAE is a method of choice for extracting high-value bioactive phenolics from blueberry pomace. Selective enrichment of different phenolic fractions is possible under select extraction conditions.

Green Extraction of Natural Antioxidants from the Sterculia nobilis Fruit Waste and Analysis of Phenolic Profile

The waste of Sterculia nobilis fruit was massively produced during food processing, which contains lots of natural antioxidants. In this study, antioxidants in the Sterculia nobilis fruit waste were extracted using the green microwave-assisted extraction (MAE) technique. The effects of five independent variables (ethanol concentration, solvent/material ratio, extraction time, temperature, and microwave power) on extraction efficiency were explored, and three major factors (ethanol concentration, extraction time, and temperature) showing great influences were chosen to study their interactions by response surface methodology. The optimal conditions were as follows: 40.96% ethanol concentration, 30 mL/g solvent/material ratio, 37.37 min extraction time at 66.76 °C, and 700 W microwave power. The Trolox equivalent antioxidant capacity value obtained in optimal conditions was in agreement with the predicted value. Besides, MAE improved the extraction efficiency compared with maceration and Soxhlet extraction methods. Additionally, the phenolic profile in the extract was analyzed by UPLC-MS/MS, and eight kinds of phenolic compounds were identified and quantified, including epicatechin, protocatechuic acid, ferulic acid, gallic acid, p-coumaric acid, caffeic acid, quercetin, and p-hydroxycinnamic acid. This study could contribute to the value-added utilization of the waste from Sterculia nobilis fruit, and the extract could be developed as food additive or functional food.

Coordinated role of soluble and cell wall bound phenols is a key feature of the metabolic adjustment in a mining woody fleabane (Dittrichia viscosa L.) population under semi-arid conditions

Environmental contamination by hazardous heavy metals/metalloids (metal(loid)s) is growing worldwide. To restrict the migration of toxic contaminants, the establishment of a self-sustainable plant cover is required. Plant growth in multi-polluted soils is a challenging issue not only by metal(loid) toxicities, but also by the co-occurrence of other stressors. Dittrichia viscosa is a pioneer Mediterranean species able to thrive in metal(loid)-enriched tailings in semi-arid areas. The aim of the present work was to examine the metabolic adjustments involved in the acclimation responses of this plant to conditions prevailing in mine-tailings during Mediterranean spring and summer. For this purpose, fully-expanded leaves, and rhizosphere soil of both mining and non-mining populations of D. viscosa grown spontaneously in south-eastern Spain were sampled in two consecutive years. Quantitative analysis of >50 biochemical, physiological and edaphic parameters were performed, including nutrient status, metal(loid) contents, leaf redox components, primary and secondary metabolites, salicylic acid levels, and soil physicochemical properties. Results showed that mining plants exhibited high foliar Zn/Pb co-accumulation capacity, without substantially affecting their photosynthetic metabolism or nutritional status even in the driest summer period. The comparison of the antioxidative/oxidative profile between mining and non-mining D. viscosa populations revealed no major seasonal changes in the content of primary antioxidants (ascorbate and GSH), or in the levels of ROS. Multivariate analysis showed that phenylalanine ammonia-lyase (PAL) and peroxidase (PRX) activities and soluble and cell wall-bound phenols were potential biomarkers for discriminating between both populations. During the dry season, a marked enhancement in the activity of both PAL and soluble PRX resulted in both a drop in the accumulation of soluble phenols and an increase of the strong metal chelator caffeic acid in the cell-wall fraction, supporting the view that the plasticity of phenylpropanoid metabolism provide an effective way to counteract the effects of stress combinations.

Impact of Storage Conditions on the Stability of Predominant Phenolic Constituents and Antioxidant Activity of Dried Piper betle Extracts

The phenolic constituents in Piper betle are well known for their antioxidant potential; however, current literature has very little information on their stability under the influence of storage factors. Present study evaluated the stability of total phenolic content (TPC) and antioxidant activity together with individual phenolic constituents (hydroxychavicol, eugenol, isoeugenol and allylpyrocatechol 3,4-diacetate) present in dried Piper betle's extract under different storage temperature of 5 and 25 °C with and without light for a period of six months. Both light and temperature significantly influenced TPC and its corresponding antioxidant activity over time. More than 95% TPC and antioxidant activity was retained at 5 °C in dark condition after 180 days of storage. Hydroxychavicol demonstrated the best stability with no degradation while eugenol and isoeugenol displayed moderate stability in low temperature (5 °C) and dark conditions. 4-allyl-1,2-diacetoxybenzene was the only compound that underwent complete degradation. A new compound, 2,4-di-tert-butylphenol, was detected after five weeks of storage only in the extracts exposed to light. Both zero-order and first-order kinetic models were adopted to describe the degradation kinetics of the extract's antioxidant activity. Zero-order displayed better fit with higher correlation coefficients (R² = 0.9046) and the half-life was determined as 62 days for the optimised storage conditions (5 °C in dark conditions).

Simultaneous optimization of ultrasonic-assisted extraction of antioxidant and anticoagulation activities of compounds from Leonurus japonicus Houtt. by response surface methodology

Leonurus japonicus Houtt. is a herbaceous annual of the Lamiaceae family with pantropical distribution; it is called motherwort in China. It plays important roles in anticoagulation and antioxidation. This study aimed to explore the optimization of ultrasound-assisted extraction of multiple compounds from motherwort as well as their antioxidant and anticoagulation activities using response surface methodology. Box–Behnken design was employed to optimize three significant influences, namely extraction time, extraction temperature and ethanol concentration. The optimum extraction parameters acquired based on a combination of the yield of the target compounds and their antioxidant and anticoagulation activities were an extraction time of 38.2 min, an extraction temperature of 30.0 °C, an ethanol concentration of 48.9% (v/v), a solid–liquid ratio of 30.0 mL g⁻¹ and an ultrasonic power of 500.0 W. Under the optimal conditions, the maximal yield of the anticoagulation and antioxidant compounds of motherwort was 0.994%; the thrombin time was 19.872 s; prothrombin time was 8.270 s; the activated partial thromboplastin time was 15.535 s; the fibrinogen was 1.420 g L⁻¹; and the 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity was 1.503 mg mL⁻¹. The optimized conditions model showed a good correlation between the predicted and experimental values. According to the results of our study, the optimization extraction significantly enabled study of the anticoagulation and antioxidant activities of compounds in motherwort; this may contribute to future research on the pharmacological activities of motherwort.

Leonurus japonicus Houtt. is a herbaceous annual of the Lamiaceae family with pantropical distribution; it is called motherwort in China.

Determination of orientin in Trollius chinensis using ultrasound-assisted extraction and high performance liquid chromatography: Several often-overlooked sample preparation parameters in an ultrasonic bath

The erratic pressure intensities and cavitation exhibited in an ultrasonic bath pose various during practical application. To achieve the most efficient experimental design, this manuscript aims to discover violently sites that are subject to the effect of slight changes in position on cavitation and ultrasound intensity distributed in the ultrasonic bath. In addition, optimization several often over-looked ultrasound parameters and experimental conditions, are intended to place the reaction vessel properly and operate under suitable experimental conditions to obtain the maximum yield of target analyte. In this study, an investigation of the various ultrasound intensities and cavitation in ultrasonic bath space were conducted with the help of the orientin yield using ultrasound-assisted extraction. Conventional parameters such as the volume fraction of ethanol, liquid-solid ratio, ultrasound irradiation power, time and frequency, and reaction temperature were investigated, all of which affect the extractive yield factors. Also several often over-looked parameters such as the extraction vessel position in the ultrasonic bath base, the distance between the bottom of the extraction vessel and the ultrasonic bath base, the diameter, the shape and the texture of the extraction vessel, height of the liquid medium and the ultrasound propagating medium salt concentration in the ultrasonic bath were tested exhaustively in this study. These results can therefore serve as a guide to optimize the usage of the ultrasonic bath for future applications.

Microwave-Assisted Extraction of Natural Antioxidants from the Exotic Gordonia axillaris Fruit: Optimization and Identification of Phenolic Compounds

Our previous study reported that the fruit of Gordonia axillaris , an edible wild fruit, possessed strong antioxidant activity. In this study, a microwave-assisted extraction (MAE) method was established to extract antioxidants from the fruit of Gordonia axillaris . The influence of five parameters, including ethanol concentration, solvent/material ratio, extraction time, extraction temperature and microwave power, was investigated by single-factor experiments. Three factors, namely ethanol concentration, solvent/material ratio, extraction time, were found to exert a major influence on extraction efficacy, and were further studied by response surface methodology to investigate their interactions. Ethanol concentration of 36.89%, solvent/material ratio of 29.56 mL/g, extraction time of 71.04 min, temperature of 40 °C, and microwave power of 400 W were found to be the optimal condition. The TEAC value was 198.16 ± 5.47 µmol Trolox/g DW under the optimal conditions, which was in conformity to the predicted value (200.28 µmol Trolox/g DW). In addition, the MAE method was compared with two conventional methods (Soxhlet extraction and maceration extraction). Results showed that the antioxidant capacity of the extract obtained by MAE method was stronger than that obtained by maceration (168.67 ± 3.88 µmol Trolox/g DW) or Soxhlet extraction (114.09 ± 2.01 µmol Trolox/g DW). Finally, several phenolic compounds in the extract were identified and quantified by UPLC-MS/MS, which were rutin, gallic acid, protocatechuic acid, epicatechin, epicatechin gallate, 2-hydrocinnamic acid, p -coumaric acid, quercetin, chlorogenic acid and ferulic acid.

Ultrasonic irradiation of low intensity with a mode of sweeping frequency enhances the membrane permeability and cell growth rate of Candida tropicalis

Here we report the enhancement of both cellular permeability and cell growth rate of Candida tropicalis after treatment with the ultrasonic irradiation of low intensity using a mode of sweeping frequency (UILS) generated by a self-developed ultrasonic device in our lab. After the ultrasonic treatment, remarkable biomass enhancement of the yeast was observed; the hyphae became significantly longer; the seeped cellular protein and nucleic acid from the yeast increased and the cellular Ca²⁺ content became lower. Illumina transcriptome sequencing showed that the ultrasonic treatment affected the expression of genes involved in diverse cellular components, biological processes and molecular functions. RT-PCR and Western blotting further confirmed the up-/down-regulation of genes in the ultrasound-treated yeasts. The optimal conditions of the ultrasonic treatment for the maximum biomass addition were determined as follows: the yeast was treated for 1h at the mid logarithmic phase, the frequency was 28±2kHz and the power density was 120W/L. Under these conditions, the Candida tropicalis biomass increased by 142.5% compared with the untreated yeast.

An efficient approach for the extraction of orientin and vitexin from Trollius chinensis flowers using ultrasonic circulating technique

Ultrasonic circulating extraction (UCE) approach was developed for effective extraction of orientin and vitexin from the flowers of Trollius chinensis successfully. In this study, some parameters potentially influencing the yields of orientin and vitexin were systematically investigated and optimized by Plackett-Burman and Box-Behnken design, and the optimum operational conditions obtained were 60% ethanol volume fraction, 1000r/min stirring speed, 30°C temperature, 28min ultrasonic irradiation time, 10mL/g liquid-solid ratio and 738W ultrasonic irradiation power. Satisfactory yields of orientin (6.05±0.19mg/g) and vitexin (0.96±0.03mg/g) were obtained in a relatively shorter extraction time under the derived optimum conditions, compared to other ultrasonic extraction methods and heat extraction methods. The mechanism of UCE procedure was discussed in detail, to illustrate the advantage of UCE in the extraction process. In addition, no degradation of orientin and vitexin and high reproducibility of the developed UCE method were observed under the optimum conditions. The proposed UCE technique with high-capacity and circulation function is a rapid and efficient sample extraction technique, and performs promising in large-scale sample preparation.

Optimization of Ultrasonic-Assisted Enzymatic Extraction Conditions for Improving Total Phenolic Content, Antioxidant and Antitumor Activities In Vitro from Trapa quadrispinosa Roxb. Residues

Stems are the important residues of Trapa quadrispinosa Roxb., which are abundant in phenolic compounds. Ultrasonic-assisted enzymatic extraction (UAEE) is confirmed as a novel extraction technology with main advantages of enhancing extraction yield and physiological activities of the extracts from various plants. In this study, UAEE was applied to obtain the highest yield of phenolic content, strongest antioxidant, and antitumor activities and to optimize the extraction conditions using response surface methodology (RSM). The extracts from the stems of T. quadrispinosa were characterized by determination of their antioxidant activities through 2,2-azinobis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS), 1,1-Diphenyl-2-picrylhydrazxyl (DPPH) radical scavenging, total antioxidant capacity (TAC), ferric reducing antioxidant capacity (FRAC) methods and of their antitumor activity by MTT method. The selected key independent variables were cellulase concentration (X₁: 1.5%–2.5%), extraction time (X₂: 20–30 min) and extraction temperature (X₃: 40–60 °C). The optimal extraction conditions for total phenolic content (TPC) value of the extracts were determined as 1.74% cellulase concentration, 25.5 min ultrasonic extraction time and 49.0 °C ultrasonic temperature. Under these conditions, the highest TPC value of 53.6 ± 2.2 mg Gallic acid equivalent (GAE)/g dry weight (DW) was obtained, which agreed well with the predicted value (52.596 mg GAE/g·DW. Furthermore, the extracts obtained from UAEE presented highest antioxidant activities through ABTS, DPPH, TAC and FRAC methods were of 1.54 ± 0.09 mmol Trolox equivalent (TE)/g·DW; 1.45 ± 0.07 mmol·TE/g·DW; 45.2 ± 2.2 mg·GAE/g·DW; 50.4 ± 2.6 μmol FeSO₄ equivalent/g·DW and lowest IC₅₀ values of 160.4 ± 11.6 μg/mL, 126.1 ± 10.8 μg/mL, and 178.3 ± 13.1 μg/mL against Hela, HepG-2 and U251 tumor cells, respectively. The results indicated that the UAEE was an efficient alternative to improve extraction yield and enhance the antioxidant and antitumor activities of the extracts. The phenolic extracts from the stems of T. quadrispinosa had significant antioxidant and antitumor activities, which could be used as a source of potential antioxidant and antitumor agents.

Effect of ultrasound assisted extraction on the physicochemical and functional properties of collagen from soft-shelled turtle calipash

The aim of the present study was to evaluate the physicochemical and functional properties of acid-soluble collagen by ultrasound assisted extraction (UASC) from calipash of soft-shelled turtle (Pelodiscus sinensis). The results showed the collagen content was increased by 16.3% in UASC over the collagen from the conventional extraction (ASC). Both ASC and UASC contained a moderate amount of imino acid (197 and 216 residues/1000 residues, respectively) and hydrophobic amino acid (353 and 391 residues/1000 residues, respectively) in amino acid composition. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses confirmed that the ultrasound treatment did not disrupt the triple-stranded helical structures in UASC. UASC had higher thermal stability compared with ASC by viscosity and differential scanning calorimetry (DSC) measurements, therefore, UASC might have the advantage to be used. In dynamic elastic behavior measurement, UASC showed a larger elasticity than ASC. With a mild modification by ultrasound, UASC had superior functional properties to ASC, including water/oil absorption capacity, water-holding capacity, emulsifying properties and foaming properties. These results suggested that UASC from the soft-shelled turtle calipash had a potential to be used widely in food, medicine, cosmetics and biomedical materials.

Ultrasound-Assisted Extraction and Identification of Natural Antioxidants from the Fruit of Melastoma sanguineum Sims

The fruit of Melastoma sanguineum Sims is an edible and sweet wild fruit. In our previous study, the fruit was found to have a strong antioxidant property. In this study, an ultrasound-assisted extraction (UAE) method was developed to extract natural antioxidants from the fruit of Melastoma sanguineum Sims, and a response surface methodology was used to optimize the conditions of UAE to maximize the extraction efficiency. The influence of five independent extraction parameters (ethanol concentration, solvent/material ratio, extracting time, temperature, and ultrasound power) on the extraction efficiency were investigated using a single factor experiment, and then a central composite rotatable design was used to investigate the interaction of three key parameters. The results showed that the optimal extraction conditions were 42.98% ethanol, 28.29 mL/g solvent/material ratio, 34.29 min extracting time, 60 °C temperature, and 600 W ultrasound power. Under these conditions, the Trolox equivalent antioxidant capacity (TEAC) value of the extracts was 1074.61 ± 32.56 μmol Trolox/g dry weight (DW). Compared with conventional maceration (723.27 ± 11.61 μmol Trolox/g DW) and Soxhlet extraction methods (518.37 ± 23.23 μmol Trolox/g DW), the UAE method improved the extraction efficiency, in a shorter period of time. In addition, epicatechin gallate, epicatechin, rutin, epigallocatechin, protocatechuic acid, chlorogenic acid, and quercetin, were identified and quantified in the fruit extracts of Melastoma sanguineum Sims by UPLC-MS/MS.