Green analytical chemistry metrics: Towards a sustainable phenolics extraction from medicinal plants

Efficient Anthocyanin Recovery from Black Bean Hulls Using Eutectic Mixtures: A Sustainable Approach for Natural Dye Development

There is a growing interest in exploring new natural sources of colorants. This study aimed to extract anthocyanins from broken black bean hulls (Phaseolus vulgaris L.) by modifying water with a eutectic mixture (choline chloride:citric acid (ChCl:Ca)). Ultrasound-assisted extraction (UAE) was employed and optimized in terms of temperature (30-70 °C), ultrasound power (150-450 W), and eutectic mixture concentration in water (1-9% (w/v)), resulting in an optimal condition of 66 °C, 420 W, and 8.2% (w/v), respectively. The main quantified anthocyanins were delphinidin-3-O-glycoside, petunidin-3-O-glycoside, and malvidin-3-O-glycoside. The half-life of the anthocyanins at 60 °C increased twelvefold in the eutectic mixture extract compared to the control, and when exposed to light, the half-life was 10 times longer, indicating greater resistance of anthocyanins in the extracted eutectic mixture. Additionally, the extracts were concentrated through centrifuge-assisted cryoconcentration, with the initial cycle almost double the extract value, making this result more favorable regarding green metrics. The first concentration cycle, which showed vibrant colors of anthocyanins, was selected to analyze the color change at different pH levels. In general, the technology that uses eutectic mixtures as water modifiers followed by cryoconcentration proved to be efficient for use as indicators in packaging, both in quantity and quality of anthocyanins.

Optimizing green approach to enhanced antioxidants from Thai pigmented rice bran using deep eutectic solvent-based ultrasonic-assisted extraction

Deep eutectic solvents (DES) have garnered significant attention as extraction media owing to their commendable attributes of being environmentally sustainable and the inherent adaptability of DES's versatile physical and chemical characteristics. The present study investigated the effects of deep eutectic solvents on the total contents of anthocyanin, phenolic, and flavonoids, as well as the antioxidant activity of Thai pigmented rice bran extract. The optimal extraction parameters for deep eutectic solvent-based ultrasonic-assisted extraction (DES-UAE) were also determined using the response surface methodology (RSM). The optimal conditions for the extraction of anthocyanins and other antioxidants from pigmented rice bran using a deep eutectic solvent were choline chloride: ethylene glycol (Ch:Eg) at a 1:2 ratio, mixed with 20 % water as a solvent. The ultrasonic-assisted extraction (UAE) at 37 kHz of frequency, 50 °C of temperature, 40 min of extraction time, and a 1:6 g/mL of solid-to-solvent ratio yielded a total anthocyanin content of 4.55 ± 0.09 mg C3G/g DW, a total phenolic content of 26.49 ± 0.62 mg GAE/g DW, a total flavonoid content of 6.57 ± 0.55 mg QE/g DW, and a percent inhibition of DPPH radical of 77.83 ± 1.51. By comparing the antioxidant content that was extracted from three cultivars of pigmented rice, it was found that Leum Pua black rice bran provided significantly higher antioxidant content compared to Hom Nin purple rice bran and Mali Dang red rice bran. This research suggests an achievable, eco-friendly, and effective method for preparing high-quality, consumer-safe Thai rice bran as a raw material for nutraceuticals.

Comprehensive Extraction and Chemical Characterization of Bioactive Compounds in Tepals of Crocus sativus L

Crocus sativus L. is largely cultivated because it is the source of saffron, a well-appreciated and valued spice, not only for its culinary use but also because of its significant biological activities. Stigmas are the main product obtained from flowers, but in addition, tepals, largely considered a waste product, represent a big source of flavonoids and anthocyanins. This study aimed to delve into the phytochemical composition of saffron tepals and investigate whether the composition was influenced by the extraction technique while investigating the main analytical techniques most suitable for the characterization of tepal extracts. The research focuses on flavonoids, a class of secondary metabolites, and their health benefits, including antioxidant, anti-inflammatory, and anticancer properties. Flavonoids occur as aglycones and glycosides and are classified into various classes, such as flavones, flavonols, and flavanones. The most abundant flavonoids in tepals are kaempferol glycosides, followed by quercetin and isorhamnetin glycosides. Overall, this review provides valuable insights into the potential uses of tepals as a source of bioactive compounds and their applications in various fields, promoting a circular and sustainable economy in saffron cultivation and processing.

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.

Insights on Chemical Crosslinking Strategies for Proteins

Crosslinking of proteins has gained immense significance in the fabrication of biomaterials for various health care applications. Various novel chemical-based strategies are being continuously developed for intra-/inter-molecular crosslinking of proteins to create a network/matrix with desired mechanical/functional properties without imparting toxicity to the host system. Many materials that are used in biomedical and food packaging industries are prepared by chemical means of crosslinking the proteins, besides the physical or enzymatic means of crosslinking. Such chemical methods utilize the chemical compounds or crosslinkers available from natural sources or synthetically generated with the ability to form covalent/non-covalent bonds with proteins. Such linkages are possible with chemicals like carbodiimides/epoxides, while photo-induced novel chemical crosslinkers are also available. In this review, we have discussed different protein crosslinking strategies under chemical methods, along with the corresponding crosslinking reactions/conditions, material properties and significant applications.

Characterization of constituents by UPLC-MS and the influence of extraction methods of the seeds of Vernonia anthelmintica willd.: extraction, characterization, antioxidant and enzyme modulatory activities

Vernonia anthelmintica Willd (VA) is a popular medicinal plant used in local and traditional medicine to manage various disorders. In order to explore the phytochemical profile, antioxidant and enzyme modulatory activities of extracts prepared from the seeds of VA, different extraction methodologies, including modern (accelerated-ASE, ultrasound-UAE, and tissue smashing-TSE extractions) and traditional (maceration and Soxhlet) extractions, were employed and their effects on the activities of the extracts were investigated. The chemical compounds of the extracts were qualitatively analyzed by ultra-high-pressure liquid chromatography-tandem mass spectrometry (UPLC-Orbitrap-MS) technique. Among them, 11 compounds were undoubtedly identified by comparison with reference substance, while 13 compounds were tentatively identified by comparison with literature data, including 8 phenolic acids, 14 flavonoids and 2 esters were identified in the extracts. Additionally, the quantitative analysis found that ASE showed the highest extraction efficiency. The antioxidant activity was determined in vitro via six standard assays. Two key enzymes related to the diseases of vitiligo (tyrosinase) and type II diabetes (α-glucosidase) were adopted to assess the activity of VA extracts against them. All extracts showed potent antioxidant ability with a predominance for that obtained by ASE, which corroborated with the high phenolic (22.62 ± 0.23 mg gallic acid equivalent (GAE)/g extract) and flavonoid contents (68.85 ± 0.25 mg rutin equivalent (RE)/g extract). The extracts obtained by ASE, UAE and SE could increase the tyrosinase activity and all the extracts displayed remarkable inhibitory activity against α-glucosidase. This study demonstrated that the VA extracts obtained by novel extraction techniques such as ASE, could be considered as a positive candidate to be utilized by the food and medical industries, not only for obtaining bioactive compounds to be used as natural antioxidants, but possibly also for its health benefits for therapeutic bio-product development.

Pressurized aqueous solutions of deep eutectic solvent (DES): A green emergent extraction of anthocyanins from a Brazilian berry processing by-product

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PLE using DES aqueous solutions is an eco-friendly method for anthocyanin recovery.

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Pressurized DES solutions can be used to valorize the jaboticaba by-product.

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DES (ChCl:Pro and ChCl:Ma) solutions had yields 50% higher than conventional solvents.

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Recovered extracts showed antioxidant, anti-diabetic, and anti-obesity potential.

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Pressurized ChCl:Ma solution maintained the color and bioactivity of the extracts.

Deep eutectic solvents (DES) are emergent solvents with high extractability of bioactive compounds. Therefore, anthocyanin rich-fractions were recovered from jaboticaba peels by combining aqueous solutions of DES and pressurized liquid extraction (PLE). The extraction occurred at 10 MPa, 12 min, with conditions optimized through response surface methodology: 47% DES concentration, 90 °C, and 5.3 mL/min flow rate. PLE with different DES (choline chloride combined with propylene glycol or malic acid) solutions were compared to conventional solvents (water and acidified water) concerning yield, thermostability, antioxidant, anti-diabetic, and anti-obesity activities. DES solutions presented anthocyanin yields up to 50% higher than conventional solvents. ChCl:Ma, with the highest anthocyanin stability (Ea = 77.5 kJ.mol⁻¹), was a promising solvent concerning color, anti-diabetic and anti-obesity potential. Environmental analysis by Green Certificate and EcoScale indicated PLE with DES solutions is a green and efficient approach to recover anthocyanin from jaboticaba peel, providing useful extracts.

The use of ultrasound in the South Cone region. Advances in organic and inorganic synthesis and in analytical methods

In organic and inorganic synthesis and in analytical methods, an external conventional heat source is usually applied to carry out a chemical reaction at a high temperature, or an extraction procedure. In the last decades, the use of ultrasound as an alternative energy source has become an interesting field of research in these topics in the South Cone region (Argentina, Chile, Uruguay, Southern Brazil and Paraguay). For this reason, the present review, covering the period 2009 to mid-2021, is a compilation of ultrasound-assisted synthetic and analytical methodologies.

Optimization of betaine-sorbitol natural deep eutectic solvent-based ultrasound-assisted extraction and pancreatic lipase inhibitory activity of chlorogenic acid and caffeine content from robusta green coffee beans

Natural deep eutectic solvent (NADES) is an alternative approach in natural product extraction with various advantages, including low toxicity, biodegradable, and suitable phytochemical compounds in a wide range of polarity. Chlorogenic acid (CGA) and caffeine, a well-known compound in the coffee bean, have various potential health benefits. This study aims to optimize the betaine–sorbitol NADES-based ultrasound-assisted extraction (UAE) method of CGA and caffeine from Robusta green coffee beans and determine the inhibitory activity of robusta green coffee beans extract of the betaine-sorbitol NADES-UAE from the optimum condition on pancreatic lipase in vitro and in silico. The betaine-sorbitol NADES-UAE factors as experimental design variable parameters include betaine-sorbitol ratio (0.5:1.2, 1.25:1.2, and 2:1.2 mol), extraction time (10, 35, and 60 min), and solid-liquid ratio (1:10, 1:20, and 1:30 g/mL). Response surface methodology and Box-Behnken Design were used to optimize the extraction process. The response surface was calculated by using CGA and caffeine content as response values. CGA and caffeine content was determined by High-Performance Liquid Chromatography. Whereas in vitro lipase inhibitory activity assay examined by spectrophotometric measurement and in silico molecular docking analysis on PDB ID: 1LPB. According to the results, the optimum conditions of the betaine-sorbitol NADES-UAE have obtained the betaine-sorbitol ratio of 1.25: 1.2 mol, solid-liquid ratio of 1:30 mg/mL, and 60 min extraction time. Furthermore, obtained Robusta green coffee extract from the optimum condition of the betaine-sorbitol NADES-UAE showed high potential to inhibit lipase activity with IC₅₀ of 18.02 μg/ml, comparable with IC₅₀ of standard CGA (11.90 μg/ml) and caffeine (15.59 μg/ml), where potential interaction of both standards was confirmed using molecular docking analysis. Our finding demonstrated the optimum condition of the betaine-sorbitol NADES-UAE method for CGA and caffeine extraction and the potential pancreatic lipase inhibition activity from the Robusta green coffee bean.

Current Progress in Natural Deep Eutectic Solvents for the Extraction of Active Components from Plants

In the last decade, natural deep eutectic solvents (NADESs) have gained more and more attention due to their green, convenient preparation, low toxicity and biodegradability. It is widely used in various fields, especially in the extraction of active components from plants, formed by the combination of hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) at a certain condition. In this article, six preparation methods of NADESs were summarized and the interactions that occur in the eutectic behavior of NADES including hydrogen bonding, electrostatic interaction and van der Waals force were also reviewed. What is more, its significant extraction capacity on flavonoids, phenols, alkaloids and plant pigments endows its extensive applications in the extraction of active components from medicinal plants. Extraction factors including solvents properties (viscosity, carbon chain length, number of hydroxyl groups), extraction condition (water content, extraction temperature, extraction time, solid-liquid ratio), extraction method and recycling method were discussed. In addition, NADESs can also be combined with other technologies, like molecular imprinting, monolithic column, to achieve efficient and specific extraction of active ingredients. Further systematic studies on the biodegradability and biotoxicity are put forward to be urgent.

Chemometric and green metric strategies for sustainable analytical methods: phenolic compounds in lettuce-NADES extracts

The combination of chemometric and green metric tools adds up to synergistic effects at method development, being highly compatible with green analytical chemistry (GAC). In the present study, both strategies were applied for the development of an ultrasound-assisted extraction mediated by Natural Deep Eutectic Solvent (UA-NADES). The Box-Behnken Design combined with multiple responses and desirability functions allowed the effective optimization of the proposed extractive methodology using an alternative green solvent. Considering the obtained results, a green UA-NADES extraction and chromatographic determination of phenolic compounds in Lactuca sativa samples were developed. Finally, the recent Analytical GREEnness metric approach was applied, and scores were compared with recent miniaturized approaches for the extraction/determination of phenolic compounds in lettuce. The results of the AGREE analysis highlight the greenness of the proposed methodology.

Selected Aspects Related to Medicinal and Aromatic Plants as Alternative Sources of Bioactive Compounds

Natural compounds obtained from different medicinal and aromatic plants have gained respect as alternative treatments to synthetic drugs, as well as raw materials for different applications (cosmetic, food and feed industries, environment protection, and many others). Based on a literature survey on dedicated databases, the aim of the present work is to be a critical discussion of aspects regarding classical extraction versus modern extraction techniques; possibilities to scale up (advantages and disadvantages of different extraction methods usually applied and the influence of extraction parameters); and different medicinal and aromatic plants' different applications (medical and industrial applications, as well as the potential use in nanotechnology). As nowadays, research studies are directed toward the development of modern, innovative applications of the medicinal and aromatic plants, aspects regarding future perspectives are also discussed.

Development of a green and efficient methodology for the heterocyclic aromatic amine determination in biomass samples generated from cigarette combustion and tobacco

A green methodology was developed for the analysis of ten heterocyclic aromatic amines (HAAs) in biomass samples from cigarette combustion such as mainstream smoke, paper ashes, as well as tobacco and paper wraps. The cellulose filter used for sample collection was also evaluated. This strategy was based on ultrasound-assisted extraction (UAE) associated with a solid-phase extraction procedure employing multi-walled carbon nanotubes (MWCNTs-SPE) as a cleanup step followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Under optimal experimental conditions, the linearity of the method was in the range from 0.08 to 160 ng cig-1, with correlation coefficients (R2) higher than 0.991. The limits of detection resulted to be between 0.03 and 0.63 ng cig-1. Concentrations of the HAAs in the mainstream smoke were from 5.7 to 145.2 ng cig-1 and in paper ashes from 0.1 to 0.6 ng cig -1, while in tobacco were between 1.0 and 38.5 ng cig-1. Meanwhile, no HAA contribution was observed in the case of paper wraps and the filter used for sample collection. The knowledge of the presence and the concentration levels of the selected HAAs in each cigarette's physical component after its combustion is essential to understand the formation processes and contribution during cigarette burning. Besides, this is the first report about the presence of some HAAs in the proposed samples. Finally, a comparative study was employed to classify the sustainability of several recent approaches for HAA extraction from cigarette combustion samples using Green Certificate as a metric tool.

Review on Extraction of Phenolic Compounds from Natural Sources Using Green Deep Eutectic Solvents

For more sustainable and environmentally friendly scientific research, it is essential to apply green chemistry principles in all areas of science. A possible area in which green chemistry principles can significantly influence the productivity and the quality of the outcome is extraction of natural products. The conventional toxic solvents can be replaced by environmentally friendly solvents known as deep eutectic solvents, which fortunately, due to their unique properties, can significantly improve extraction efficiency. In this literature review, the extraction of a specific class of natural products, phenolic compounds, using different types of green deep eutectic solvents has been reviewed. Within this review, the composition of those solvents used to extract different types of phenolic compounds has been discussed. In addition, the factors affecting their extraction, extracting solvent component structure, molar ratio of extracting solvent components, extraction temperature, solid to extraction solvent ratio, and water content, have been evaluated.

Innovative Extraction Techniques Using Deep Eutectic Solvents and Analytical Methods for the Isolation and Characterization of Natural Bioactive Compounds from Plant Material

The growing interest of the food, pharmaceutical and cosmetics industries in naturally occurring bioactive compounds or secondary plant metabolites also leads to a growing demand for the development of new and more effective analysis and isolation techniques. The extraction of bioactive compounds from plant material has always been a challenge, accompanied by increasingly strict control requirements for the final products and a growing interest in environmental protection. However, great efforts have been made in this direction and today a considerable number of innovative extraction techniques have been developed using green, environmentally friendly solvents. These solvents include the deep eutectic solvents (DES) and their natural equivalents, the natural deep eutectic solvents (NADES). Due to their adjustable physical-chemical properties and their green character, it is expected that DES/NADES could be the most widely used solvents in the future, not only in extraction processes but also in other research areas such as catalysis, electrochemistry or organic synthesis. Consequently, this review provided an up-to-date systematic overview of the use of DES/NADES in combination with innovative extraction techniques for the isolation of bioactive compounds from various plant materials. The topicality of the field was confirmed by a detailed search on the platform WoS (Web of Science), which resulted in more than 100 original research papers on DES/NADES for bioactive compounds in the last three years. Besides the isolation of bioactive compounds from plants, different analytical methods are presented and discussed.

A Glimpse into the Extraction Methods of Active Compounds from Plants

Naturally active compounds are usually contained inside plants and materials thereof. Thus, the extraction of the active compounds from plants needs appropriate extraction methods. The commonly employed extraction methods are mostly based on solid-liquid extraction. Frequently used conventional extraction methods such as maceration, heat-assisted extraction, Soxhlet extraction, and hydrodistillation are often criticized for large solvent consumption and long extraction times. Therefore, many advanced extraction methods incorporating various technologies such as ultrasound, microwaves, high pressure, high voltage, enzyme hydrolysis, innovative solvent systems, adsorption, and mechanical forces have been studied. These advanced extraction methods are often better than conventional methods in terms of higher yields, higher selectivity, lower solvent consumption, shorter processing time, better energy efficiency, and potential to avoid organic solvents. They are usually designed to be greener, more sustainable, and environment friendly. In this review, we have critically described recently developed extraction methods pertaining to obtaining active compounds from plants and materials thereof. Main factors that affect the extraction performances are tuned, and extraction methods are chosen in line with the properties of targeted active compounds or the objectives of extraction. The review also highlights the advancements in extraction procedures by using combinations of extraction methods to obtain high overall yields or high purity extracts.

Hydroxypropyl-β-Cyclodextrin as a Green Co-Solvent in the Aqueous Extraction of Polyphenols from Waste Orange Peels

There is, to-date, an expanding interest concerning the use of cyclodextrins as green food-grade co-solvents in the aqueous extraction of polyphenols, however, data regarding polyphenol extraction from waste orange peels (WOP) are lacking. On this ground, hydroxypropyl β-cyclodextrin (HP-β-CD), a highly water-soluble cyclodextrin, was used to develop a simple and straightforward methodology for the effective recovery of WOP polyphenols. Process optimization by response surface showed that maximum total polyphenol recovery (26.30 ± 1.49 mg gallic acid equivalents g−1 dry mass) could be accomplished with 15 mM HP-β-CD at 40 °C. On the other hand, integration of ultrasonication pretreatment was found unsuitable, as it resulted in reduced polyphenol yield. Examination of solvent acidity indicated that polyphenol extraction may be enhanced at pH 4, but the difference was non-significant (p > 0.05) compared to yields attained at pH 2, 3, and 5. Extraction of WOP polyphenols with HP-β-CD was shown to provide significantly higher hesperidin yield compared to 60% (v/v) aqueous ethanol, which suggested selectivity of HP-β-CD toward this polyphenolic metabolite.

Batch Stirred-Tank Green Extraction of Salvia fruticosa Mill. Polyphenols Using Newly Designed Citrate-Based Deep Eutectic Solvents and Ultrasonication Pretreatment

A series of citrate salts were tested as hydrogen bond acceptors to synthesize deep eutectic solvents (DES) based on lactic acid and glycerol, used as hydrogen bond donors. The DES produced were then screened to identify the highest performing system for the effective extraction of polyphenolic phytochemicals from the medicinal plant Salvia fruticosa Mill. (Greek sage). The most efficacious DES was the one composed of lactic acid and sodium citrate dibasic, at a molar ratio of 15:1 (LA-SCDB15). Furthermore, for the first time there has been evidence concerning DES pH and extraction efficiency. Using this solvent, a batch, stirred-tank extraction process was developed, by employing ultrasonication pretreatment and response surface methodology. The optimal settings determined were stirring speed 900 rpm, proportion of DES/water 77% (w/v), and ultrasonication pretreatment time 15 min. By adjusting these optimal settings, the predicted maximum total polyphenol yield was calculated to be 79.93 ± 1.92 mg gallic acid equivalents g−1 dry mass. The examination of temperature effects demonstrated that the batch, stirred-tank extraction stage was very energy-efficient, with a barrier of 7.64 kJ mol−1. Comparison of the extraction of Salvia fruticosa polyphenols with other green processes previously developed, illustrated the high extraction capacity of LA-SCDB15. The major polyphenols identified in the extracts produced under optimized settings were chlorogenic acid, luteolin 7-O-glucuronide and rosmarinic acid.

Innovative Approaches for Recovery of Phytoconstituents from Medicinal/Aromatic Plants and Biotechnological Production

Continuously growing demand for plant derived therapeutic molecules obtained in a sustainable and eco-friendly manner favors biotechnological production and development of innovative extraction techniques to obtain phytoconstituents. What is more, improving and optimization of alternative techniques for the isolation of high value natural compounds are issues having both social and economic importance. In this critical review, the aspects regarding plant biotechnology and green downstream processing, leading to the production and extraction of increased levels of fine chemicals from both plant cell, tissue, and organ culture or fresh plant materials and the remaining by-products, are discussed.

NADES-mediated folk plant extracts as novel antifungal agents against Candida albicans

Candida albicans is an opportunistic pathogenic yeast commonly found in mouth, gastrointestinal tract and vagina. Under certain conditions, it causes skin, mucosal and systemic infections. With growing concern over the emergence of resistant strains to conventional antifungals, the development of novel antifungal agents for the management of this pathogen is an urgent need. In the present work, novel bioextracts from folk medicinal plants were directly used as active ingredient in a topical formulation for dermal candidiasis. With the aim to replace hazardous traditional reagents, a natural solvent composed by lactic acid: glucose: water (LGH) was used as vehicle for bioactive compound extraction. Furthermore, phenolic and alkaloid composition were determined by HPLC and their individual antifungal effect was evaluated. LGH extracts of Larrea spices demonstrate a significant antimicrobial activity against C. albicans being higher than their individual bioactive constituents. Notably, the mixture of Larrea cuneifolia and L divaricata extracts in topical formulations reveal a synergistic antifungal effect highlighting their potential for candidiasis treatment.