深度低共熔溶剂在提取植物中的黄酮类化合物方面的应用
Abstract
摘要
Deep Eutectic Solvents (DESs) are emerging as green alternatives to conventional solvents for extracting flavonoid compounds, which possess significant antioxidant and bioactive properties. This review outlines the unique advantages of DESs in flavonoid extraction, including their tailorable physicochemical properties, low toxicity, and biodegradability. DESs, formed by hydrogen bond donors and acceptors, offer superior extraction efficiency and selectivity while reducing environmental impact. Future developments will likely concentrate on scaling up DES extraction processes, enhancing sustainability, and integrating with other green chemistry practices. The optimization of DES composition and extraction conditions is essential for maximizing flavonoid yields and preserving their bioactivity. DESs hold promise for sustainable extraction in the food, pharmaceutical, and cosmetic industries.
深共熔溶剂(DES)正逐渐成为提取黄酮化合物的绿色替代品,这些化合物具有显著的抗氧化和生物活性特性。本综述概述了 DES 在黄酮提取中的独特优势,包括其可调的物理化学特性、低毒性和生物降解性。由氢键供体和受体形成的 DES 提供了更高的提取效率和选择性,同时减少了对环境的影响。未来的发展可能集中在扩大 DES 提取过程的规模、增强可持续性以及与其他绿色化学实践的整合上。优化 DES 成分和提取条件对于最大化黄酮产量和保护其生物活性至关重要。DES 在食品、制药和化妆品行业的可持续提取中具有良好的前景。
Keywords: Deep Eutectic Solvents, Flavonoids, Extraction, Green Chemistry, Sustainability
关键词:深共晶溶剂,类黄酮,提取,绿色化学,可持续性
引言:Flavonoid compounds are a class of polyphenolic secondary metabolites widely present in plants in nature. The basic skeleton of flavonoid compounds is formed by two benzene rings (Ring A and Ring B) connected by a three-carbon chain that contains an oxygen atom. This basic structure is known as 2-phenylchromene. The diversity of flavonoid compounds comes from different substituent groups on this basic skeleton. These different structural types endow flavonoid compounds with different physicochemical properties and biological activities. These biological activities include antioxidant, anti-inflammatory, antitumor, and antiviral effects, making flavonoid compounds promising for applications in medicine, the food industry, health supplements, and cosmetics. With the increasing public awareness of health and environmental protection, the demand for research and application of flavonoid compounds is growing.
引言:类黄酮化合物是一类广泛存在于自然界植物中的多酚类次级代谢物。类黄酮化合物的基本骨架由两个苯环(环 A 和环 B)通过一个包含氧原子的三碳链连接而成。这一基本结构被称为 2-苯基色烯。类黄酮化合物的多样性源于这个基本骨架上不同的取代基。这些不同的结构类型赋予类黄酮化合物不同的物理化学性质和生物活性。这些生物活性包括抗氧化、抗炎、抗肿瘤和抗病毒作用,使得类黄酮化合物在医药、食品工业、保健品和化妆品等领域具有广阔的应用前景。随着公众对于健康和环境保护意识的提高,对类黄酮化合物研究和应用的需求也在增加。
Traditional methods for extracting flavonoid compounds, including solvent extraction, ultrasonic-assisted extraction, microwave-assisted extraction, and supercritical fluid extraction, have achieved certain results in terms of extraction efficiency but also have some limitations. These methods can lead to issues like organic solvent residue, time-consuming operations, high energy consumption, and environmental pollution. Moreover, these extraction technologies may disrupt the molecular structure of flavonoid compounds during the process, affecting their biological activity and limiting their effectiveness in practical applications.
传统的类黄酮化合物提取方法,包括溶剂提取、超声辅助提取、微波辅助提取和超临界流体提取,在提取效率方面取得了一定成果,但也存在一些局限性。这些方法可能导致有机溶剂残留、操作耗时高、能量消耗大以及环境污染。此外,这些提取技术在过程中过可能会破坏类黄酮化合物的分子结构,影响其生物活性,从而限制其在实际应用中的效果。
To overcome these limitations, Deep Eutectic Solvents (DES) have emerged as a new type of green solvent, garnering widespread attention due to their environmental friendliness, low cost, ease of preparation, and unique physicochemical properties. DES are typically formed by the interaction of hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA) through hydrogen bonding, which not only lowers the melting point of the mixture but also endows DES with various unique properties, such as low toxicity, high biodegradability, and adjustable solubility. These characteristics enable DES to exhibit high efficiency and selectivity in the extraction of flavonoids while reducing the potential impact on the environment.
为了克服这些限制,深共熔溶剂(DES)作为一种新型绿色溶剂应运而生,因其环保、成本低、易于制备以及独特的物理化学性质而受到广泛关注。DES 通常是通过氢键供体(HBD)和氢键受体(HBA)之间的相互作用形成的氢键,这不仅降低了混合物的熔点,还赋予了 DES 多种独特的性能,如低毒性、高生物降解性和可调溶解性。这些特性使得 DES 在提取黄酮类化合物时表现出高效性和选择性,同时减少对环境的潜在影响。
Therefore, this article aims to review the application of DES in the extraction of flavonoids, discussing their basic characteristics, preparation methods, factors affecting extraction efficiency, classification and selection of DES, green chemistry advantages, and the optimization and challenges of extraction technology. By analyzing the current status and future development trends of DES extraction technology, this article will provide a comprehensive perspective on the research and application of DES in flavonoid extraction and emphasize the importance of further studying the extraction mechanism and optimizing the extraction process.
因此,本文旨在回顾深度共溶剂(DES)在黄酮提取中的应用,讨论其基本特性、制备方法、影响提取效率的因素、DES 的分类与选择、绿色化学优势,以及提取技术的优化与挑战。通过分析 DES 提取技术的现状和未来发展趋势,本文将为黄酮提取中 DES 的研究与应用提供全面的视角,并强调进一步研究提取机制和优化提取过程的重要性。
黄酮类化合物
Flavonoids are a large group of naturally occurring polyphenolic compounds that are widely found in plants. They are found in many forms in fruits, vegetables, tea, wine, and other foods of plant origin.
类黄酮是一大类自然存在的多酚化合物,广泛分布于植物中。它们以多种形式存在于水果、蔬菜、茶、葡萄酒及其他植物源食品中。
2.1Basic Chemical Structure of Flavonoid Compounds
2.1类黄酮化合物的基本化学结构
Flavonoid compounds are a class of polyphenolic secondary metabolites widely present in plants. The basic skeleton of flavonoid compounds consists of two benzene rings (A ring and B ring) connected by a three-carbon chain that forms a closed pyran ring (C ring). This structure is known as 2-phenylchromen-4-one. The diversity of flavonoid compounds arises from different substituent groups attached to this basic skeleton, including hydroxyl, methoxy, and glycosyl groups.
类黄酮化合物是一类广泛存在于植物中的多酚类次级代谢物。类黄酮化合物的基本骨架由两个苯环(A 环和 B 环)通过一个形成封闭吡喃环(C 环)的三碳链连接而成。该结构被称为 2-苯基色烯-4-酮。类黄酮化合物的多样性源于附加在这一基本骨架上的不同取代基,包括羟基、甲氧基和糖基。
2.2Major Types of Flavonoid Compounds
2.2类黄酮化合物的主要类型
Flavones: Flavones have a double bond between C2 and C3 and a ketone at C4. Examples include apigenin and luteolin.
黄酮类: 黄酮类在 C2 和 C3 之间有一个双键,在 C4 处有一个酮。例子包括阿莫烈素和黄酮素。
Flavonols: Flavonols are similar to flavones but have an additional hydroxyl group at the C3 position. Examples include quercetin and kaempferol.
黄酮醇: 黄酮醇与黄酮相似,但在 C3 位置上具有一个额外的羟基。例子包括槲皮素和凯瑟醇。
Isoflavones: Isoflavones have the B ring attached at the C3 position of the C ring instead of the C2 position. Examples include genistein and daidzein.
异黄酮: 异黄酮在 C 环的 C3 位置连有 B 环,而不是 C2 位置。例子包括黄酮素和大豆异黄酮。
Flavanones: Flavanones have a saturated C ring, lacking the double bond between C2 and C3. Examples include naringenin and hesperetin.
黄酮酮:黄酮酮具有饱和的 C 环,缺少 C2 和 C3 之间的双键。例子包括柚皮素和橙皮素。
Flavanols (Flavan-3-ols): Flavanols have a hydroxyl group at the C3 position and lack the double bond between C2 and C3. Examples include catechin and epicatechin.
黄酮醇(Flavan-3-ols): 黄酮醇在 C3 位置上具有一个羟基,且在 C2 和 C3 之间缺乏双键。示例包括儿茶素和表儿茶素。
Anthocyanidins: Anthocyanidins have a positively charged oxygen at the C ring, giving them their characteristic color. Examples include cyanidin and delphinidin.
花青素: 花青素在 C 环上具有一个带正电的氧,使其具有特征颜色。如:氰化物和德尔菲尼丁。
Chalcones: Chalcones have an open-chain structure with two aromatic rings connected by a three-carbon α,β-unsaturated carbonyl system. Examples include chalcone and phloretin.
查尔酮: 查尔酮具有开放链结构,由两个芳香环通过三碳α,β-不饱和羰基系统连接在一起。示例包括查尔酮和菲洛汀。
Dihydroflavonoids: Dihydroflavonoids are similar to flavonoids but have a fully saturated C ring. Examples include dihydroquercetin and dihydrokaempferol.
二氢黄酮: 二氢黄酮与黄酮类似,但具有完全饱和的 C 环。例子包括二氢槲皮素和二氢凯普弗尔。
2.3Relationship Between Structure and Biological Activity
2.3结构与生物活性之间的关系
In the realm of natural compounds, flavonoids stand out for their diverse and potent biological activities, which are intricately linked to their unique chemical structures.
在天然化合物的领域中,类黄酮因其多样和强大的生物活性而脱颖而出,这些活性与其独特的化学结构密切相关。
Flavonoids are renowned for their antioxidant properties, which are significantly influenced by the presence and position of hydroxyl groups on their molecular structure. Particularly, the 3',4'-dihydroxy configuration in the B ring is a hallmark for enhanced scavenging of reactive oxygen species (ROS) and metal ion chelation. This structural feature allows flavonoids to neutralize free radical, thereby preventing oxidative damage to cellular components, including lipids, proteins, and DNA. The antioxidant capacity of flavonoids is further augmented by the ability to regenerate other antioxidants, such as vitamin E and vitamin C, thus reinforcing the body's defense against oxidative stress.
类黄酮因其抗氧化特性而闻名,这些特性受到其分子结构中羟基位置和数量的显著影响。特别是 B 环中的 3',4'-二羟基构型是增强活性氧种(ROS)和金属离子螯合的标志。这一结构特征使类黄酮能够中和自由基,从而防止对细胞成分的氧化损伤,包括脂质、蛋白质和 DNA。类黄酮的抗氧化能力还通过再生其他抗氧化剂(如维生素 E 和维生素 C)的能力进一步增强,从而加强身体对氧化应激的防御。
The anti-inflammatory effects of flavonoids are attributed to their ability to modulate key enzymes in the inflammatory pathway. Flavonoids with hydroxyl groups at specific positions can effectively inhibit cyclooxygenase (COX) and lipoxygenase (LOX) enzymes, which are central to the production of pro-inflammatory mediators. Flavonols, such as quercetin, exemplify the potent anti-inflammatory action of flavonoids, demonstrating the ability to reduce inflammation at various levels, from the inhibition of enzyme activity to the modulation of cytokine expression.
黄酮类化合物的抗炎效果归因于它们调节炎症通路中关键酶的能力。特定位置上的羟基黄酮类化合物可以有效抑制环氧合酶(COX)和脂氧合酶(LOX)这两种在促炎介质生成中占核心地位的酶。类黄酮,例如槲皮素,体现了黄酮类化合物强大的抗炎作用,展示了从抑制酶活性到调节细胞因子表达等各个层面减少炎症的能力。
The anticancer properties of flavonoids are deeply rooted in their structural features. The presence of a double bond between C2 and C3, along with a ketone group at C4, endows flavonoids with the capability to induce apoptosis and inhibit cell proliferation in cancer cells. These structural elements facilitate the interaction of flavonoids with cellular targets, such as nuclear factor kappa B (NF-κB) and protein kinases, which are often dysregulated in cancer. By disrupting the cancer cell's signaling pathways and enhancing the immune response, flavonoids contribute to the prevention and treatment of cancer.
类黄酮的抗癌特性根植于其结构特征。C2 和 C3 之间的双键以及 C4 处的酮基使类黄酮具备诱导细胞凋亡和抑制癌细胞增殖的能力。这些结构元素促进了类黄酮与细胞靶标的相互作用,例如在癌症中常常失调的核因子κB (NF-κB)和蛋白激酶。通过破坏癌细胞的信号通路并增强免疫反应,类黄酮有助于预防和治疗癌症。
Flavonoids have emerged as significant players in cardiovascular health, with flavan-3-ols (catechins) and flavonols (quercetin) leading the way. These compounds exert cardioprotective effects by improving endothelial function, reducing blood pressure, and inhibiting platelet aggregation. The underlying mechanisms involve the modulation of nitric oxide synthesis, the inhibition of low-density lipoprotein (LDL) oxidation, and the suppression of inflammatory processes in the vasculature. As a result, flavonoids can mitigate the risk of atherosclerosis and other cardiovascular diseases.
黄酮类化合物已成为心血管健康的重要参与者,其中黄烷-3-醇(儿茶素)和黄酮类物质(槲皮素)处于领先地位。这些化合物通过改善内皮功能、降低血压和抑制血小板聚集来发挥心脏保护作用。其基本机制涉及一氧化氮合成的调节、低密度脂蛋白(LDL)氧化的抑制以及对血管炎症过程的抑制。因此,黄酮类化合物可以减轻动脉粥样硬化和其他心血管疾病的风险。
Flavonoids also exhibit antiviral properties, which are particularly relevant in the context of viral replication and immune response modulation. Certain flavonoids, such as flavones and flavonols, can inhibit viral replication by interacting with viral proteins and enzymes. Additionally, they can modulate the host's immune response, enhancing the body's ability to combat viral infections. The antiviral activity of flavonoids is a testament to their versatility and potential in developing new therapeutic strategies against viral diseases.
黄酮类化合物也展现出抗病毒特性,这在病毒复制和免疫反应调节的背景下尤为相关。某些黄酮,如黄酮和黄酮醇,可以通过与病毒蛋白和酶相互作用来抑制病毒复制。此外,它们还可以调节宿主的免疫反应,增强身体抵御病毒感染的能力。黄酮类化合物的抗病毒活性证明了它们的多样性和在开发新疗法应对病毒性疾病方面的潜力。
In summary, flavonoids represent a class of compounds with a broad spectrum of biological activities that are intricately linked to their chemical structures. Their antioxidant, anti-inflammatory, anticancer, cardioprotective, and antiviral effects position flavonoids as promising candidates for the prevention and treatment of various diseases.
总之,类黄酮代表了一类具有广泛生物活性的化合物,这些活性与它们的化学结构密切相关。它们的抗氧化、抗炎、抗癌、心脏保护和抗病毒作用使类黄酮成为预防和治疗各种疾病的有前景的候选者。
2.4黄酮类化合物的常规提取
2.4 黄酮类化合物的常规提取
Flavonoids are a class of plant secondary metabolites that possess a wide range of biological activities, including antioxidant, anti-inflammatory, and anticancer properties. Due to their significant health benefits, there has been a growing interest in the extraction and isolation of flavonoids from natural sources. Below will summarize the conventional methods used for the extraction of flavonoids.
类黄酮是一类植物次级代谢物,具有广泛的生物活性,包括抗氧化、抗炎和抗癌特性。由于它们显著的健康益处,提取和分离天然来源中类黄酮的兴趣日益增长。Below将总结用于提取类黄酮的传统方法。
Solvent Extraction: This is one of the most traditional methods for extracting flavonoids from plant materials. The process involves the use of organic solvents, such as methanol, ethanol, or acetone, to disrupt cell walls and dissolve flavonoids. The solvent choice is critical, as it should be able to penetrate the plant matrix effectively and dissolve the target compounds without causing degradation. The efficiency of this method can be enhanced by increasing the solvent-to-solid ratio, extraction temperature, and time. However, the use of large amounts of organic solvents and the need for further purification steps can make this method less environmentally friendly and economically viable.
溶剂萃取:这是从植物材料中提取类黄酮的最传统方法之一。该过程涉及使用有机溶剂,如甲醇、乙醇或丙酮,来破坏细胞壁并溶解类黄酮。溶剂的选择至关重要,因为它应能够有效渗透植物基质并溶解目标化合物,而不导致降解。通过增加溶剂与固体的比例、萃取温度和时间,可以提高该方法的效率。然而,大量使用有机溶剂以及需要进一步的纯化步骤可能使该方法在环境友好性和经济可行性方面较差。
Ultrasonic-Assisted Extraction (UAE): UAE employs ultrasound waves to enhance the mass transfer of flavonoids from the plant matrix into the solvent. The acoustic cavitation generated by ultrasound leads to the disruption of cell walls, increasing the extraction efficiency. This method is faster than conventional solvent extraction and requires less solvent, making it more environmentally sustainable. However, the scalability of UAE to an industrial level and the potential for thermal degradation of heat-sensitive flavonoids are concerns that need to be addressed.
超声辅助提取(UAE):UAE 利用超声波增强黄酮类化合物从植物基质转移到溶剂中的质量传递。超声产生的声学空化破坏了细胞壁,提高了提取效率。这种方法比传统溶剂提取更快,所需溶剂更少,使其更加环保。然而,UAE 在工业规模上的可扩展性以及热敏感黄酮的热降解潜力是需要解决的关注点。
Microwave-Assisted Extraction (MAE): MAE uses microwave energy to heat the solvent and plant material, which accelerates the extraction process. The rapid heating can lead to higher yields of flavonoids in a shorter time compared to conventional methods. MAE is energy-efficient and can be easily automated. However, similar to UAE, there is a risk of thermal degradation of flavonoids if the extraction conditions are not optimized.
微波辅助提取(MAE):MAE 利用微波能量加热溶剂和植物材料,从而加速提取过程。与传统方法相比,快速加热可以在更短的时间内获得更高的类黄酮产量。MAE 能效高,易于自动化。然而,类似于超声辅助提取(UAE),如果提取条件没有优化,会存在类黄酮的热降解风险。
Enzyme-Assisted Extraction: This method involves the use of enzymes to break down the cell wall components, such as cellulose and pectin, thereby facilitating the release of flavonoids. Enzymatic extraction is a mild and selective process that can preserve the biological activity of the extracted compounds. It is particularly useful for extracting flavonoids with heat-sensitive glycosidic bonds. The main limitation is the additional cost associated with enzyme preparation and the longer extraction times required.
酶辅助提取:这种方法涉及使用酶来分解细胞壁成分,如纤维素和果胶,从而促进黄酮的释放。酶提取是一种温和且选择性的方法,可以保持提取化合物的生物活性。它特别适用于提取热敏感的糖苷键的黄酮。主要的限制是与酶制备相关的额外成本以及所需的较长提取时间。
Supercritical Fluid Extraction (SFE): SFE uses supercritical fluids, typically carbon dioxide, to extract flavonoids. The supercritical fluid's solvating power can be tuned by adjusting pressure and temperature, allowing for selective extraction. SFE is a green method that avoids the use of organic solvents and can operate at lower temperatures, preventing thermal degradation. However, the high capital and operational costs, along with the need for specialized equipment, limit its widespread application.
超临界流体提取(SFE):SFE 使用超临界流体,通常是二氧化碳,来提取类黄酮。通过调节压力和温度,可以调节超临界流体的溶解能力,实现选择性提取。SFE 是一种绿色方法,避免了使用有机溶剂,并且可以在较低温度下操作,防止热降解。然而,高昂的资本和运营成本以及对专用设备的需求限制了其广泛应用。
In conclusion, the choice of extraction method for flavonoids depends on the desired yield, quality of the extract, scalability, and economic considerations. Conventional solvent extraction is simple but uses large amounts of solvents. Ultrasonic and microwave-assisted extractions offer speed and efficiency but require careful control of conditions to prevent degradation. Enzyme-assisted extraction is gentle and selective but can be slower and more expensive. Supercritical fluid extraction is environmentally friendly and selective but has high operational costs. Each method has its merits and drawbacks.
总之,类黄酮的提取方法选择取决于所需的产量、提取物的质量、可扩展性和经济考虑。传统的溶剂提取方法简单,但使用大量溶剂。超声波和微波辅助提取提供了速度和效率,但需要仔细控制条件以防止降解。酶辅助提取温和且选择性强,但可能较慢且成本更高。超临界流体提取环境友好且选择性强,但运营成本高。每种方法都有其优缺点.
深度低共熔溶剂(DES)的基本特性
DES的定义及其合成机制
DES 的定义及其合成机制
Deep Eutectic Solvents (DESs) are a unique class of solvents that have garnered significant attention due to their potential as green alternatives to conventional solvents. They are formed by the complexation of a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA), leading to a eutectic mixture that exhibits a melting point significantly lower than the melting points of the individual components. This definition is grounded in thermodynamic principles and distinguishes DESs as a subclass of eutectic mixtures, requiring a degree of thermodynamic nonideality in the liquid phase.
深共晶溶剂(DESs)是一类独特的溶剂,因其作为传统溶剂的绿色替代品而受到广泛关注。它们是通过氢键供体(HBD)与氢键受体(HBA)的络合形成的,形成的共晶混合物具有明显低于各个组成成分熔点的熔点。这个定义基于热力学原理,将 DESs 区分为共晶混合物的一个子类,要求液相具有一定的热力学非理想性。
DESs are not to be confused with ionic liquids, as they are fundamentally different in their composition; while ionic liquids are pure compounds, DESs are mixtures. They also should not be assumed to be a type of ionic liquid-related compound, as they have distinct characteristics. The formation of DESs is not solely based on the presence of hydrogen bonding between the donor and acceptor but requires a difference in acidity between the two components, preventing proton transfer and leading to a shared proton state.
深共晶溶剂(DESs)与离子液体不同,二者在组成上具有根本差异;离子液体是纯化合物,而深共晶溶剂是混合物。也不应假定它们是与离子液体相关的化合物,因为它们具有独特的特性。深共晶溶剂的形成不仅仅依赖于供体和受体之间氢键的存在,还需要两种成分之间的酸性差异,以防止质子转移,从而导致共享质子状态的形成。
A key feature of DESs is the enhanced decrease in melting points through favorable interactions between the two compounds, which necessitates negative deviations from thermodynamic ideality. This results from the interaction between Lewis or Brønsted acids and bases of different acidities. DESs, therefore, are eutectic solvents whose components present enthalpic-driven negative deviations from thermodynamic ideality, and at least one component should be a solid with its melting point depressed through DES formation, becoming a liquid at the desired operating temperature.
DES 的一个关键特征是通过两种化合物之间的有利相互作用增强熔点的降低,这需要热力学理想性下的负偏离。这是由于不同酸度的路易斯酸或布朗斯特酸与碱之间的相互作用。因此,DES 是共晶溶剂,其组分呈现出热力学理想性下的富熵负偏离,并且至少一个组分应为固体,其熔点通过 DES 形成而降低,在所需的操作温度下成为液体。
Deep Eutectic Solvents (DESs) are synthesized through the strategic combination of a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA), which results in a significant depression of the melting point due to the formation of a eutectic mixture. This mixture exhibits thermodynamic nonideality, characterized by enthalpy-driven negative deviations from ideal behavior, which is essential for classifying a mixture as a DES.
深共晶溶剂(DESs)是通过氢键供体(HBD)和氢键接受体(HBA)之间的战略组合合成的,这导致由于形成共晶混合物而显著降低熔点。该混合物表现出热力学非理想性,其特征是由于焓驱动的负偏离理想行为,这对于将混合物分类为 DES 至关重要。
The synthesis of DESs involves the selection of precursors that promote strong intermolecular interactions between the HBD and HBA, while minimizing interactions within their own species. This asymmetry in polarity leads to the formation of a complex that has a lower melting point than the individual components. The DES formation is influenced by the choice of HBDs and HBAs, with a preference for lone HBAs, such as quaternary ammonium salts, and asymmetric HBDs, which possess a particularly acidic hydrogen bond donor site.
DES 的合成涉及选择促进 HBD 与 HBA 之间强分子间相互作用的前体,同时最小化它们自身物种之间的相互作用。这种极性的非对称性导致形成的复合物的熔点低于单独的组分。DES 的形成受到 HBD 和 HBA 选择的影响,倾向于选择孤立的 HBA,例如季铵盐,以及具有特别酸性氢键供体位点的非对称 HBD。
The nonideality of the DES is further enhanced by the presence of strong hydrogen bonds or other types of strong interactions, such as halogen bonds, between the donor and acceptor. This interaction must be such that it results in a proton-sharing state without leading to proton transfer, which would result in the formation of protic ionic liquids rather than DESs.
DES 的非理想性因供体和受体之间存在强氢键或其他类型的强相互作用(如卤素键)而进一步增强。这种相互作用必须使其形成一种质子共享状态,而不导致质子转移,否则将形成质子离子液体而不是 DES。
DESs are not restricted to fixed stoichiometric ratios and can be optimized for performance by adjusting the composition of the eutectic solvent. This tunable potential allows for a wide composition range and maximizes the performance of the solvent for specific applications.
DESs 并不局限于固定的化学计量比,可以通过调整共晶溶剂的成分来优化其性能。这种可调性使得成分范围广泛,最大限度地提高了溶剂在特定应用中的性能。
Understanding the thermodynamic behavior of the DES is crucial for their design and application. The solid-liquid equilibrium (SLE) phase diagram of the system provides insights into the melting properties and the thermodynamic nonideality of the mixture. DESs are typically formed when the experimental melting temperatures are lower than those predicted by an ideal phase diagram, indicating the presence of negative deviations from thermodynamic ideality.
理解深共晶溶剂(DES)的热力学行为对于其设计和应用至关重要。该系统的固液平衡(SLE)相图提供了关于熔融性质和混合物热力学非理想性的见解。当实验熔融温度低于理想相图预测的温度时,通常会形成 DES,这表明存在热力学理想性负偏差的情况。
In essence, the synthesis of Deep Eutectic Solvents (DESs) is predicated on the judicious selection of appropriate hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs). This selection is coupled with the enhancement of robust intermolecular interactions between the two components. A critical aspect of this process is the comprehension of the thermodynamic nonideality that is inherent to DESs. This understanding is paramount, as it enables the deliberate and rational design of DESs. The end result is a solvent with properties that are precisely tailored to meet the specific demands of a broad array of applications. This strategic approach to DES synthesis ensures that the resulting solvents are not only effective but also versatile, catering to the unique requirements of various industrial and research domains.
本质上,深共熔溶剂(DESs)的合成基于对适当的氢键供体(HBDs)和氢键受体(HBAs)的明智选择。这一选择与增强两种成分之间强大的分子间相互作用相结合。这个过程的一个关键方面是理解 DESs 固有的热力学非理想性。这种理解至关重要,因为它使得 DESs 的设计变得有意识和合理。最终结果是一个具有精确调整的特性,以满足广泛应用的特定需求。这种对 DES 合成的战略性方法确保了所得到的溶剂不仅有效,而且多功能,能够满足各种工业和研究领域的独特要求。
DES的物理化学特性
DES 的物理化学特性
Phase Behavior: DESs exhibit unique phase behavior, with the eutectic point representing the lowest melting temperature in a solid-liquid phase diagram. The freezing points of DESs usually range between -69 and 149 °C, and their phase diagrams are essential for understanding their solubility and melting properties.
相行为:深度熔融盐(DESs)表现出独特的相行为,共晶点代表固液相图中的最低熔化温度。深度熔融盐的冻结点通常在-69 到 149 摄氏度之间,其相图对于理解其溶解度和熔化性质至关重要。
Density: Most DESs have higher densities than water, typically between 1.0 and 1.3 g/cm³ at 25 °C. However, hydrophobic deep eutectics may have lower densities than water. Density decreases linearly with increasing temperature and is influenced by the choice of hydrogen bond donor and molar ratio.
密度:大多数深共熔溶剂的密度高于水,通常在 25°C 时介于 1.0 和 1.3 g/cm³之间。然而,疏水性的深共熔溶剂的密度可能低于水。密度随着温度的升高而线性减少,并受到氢键供体的选择和摩尔比的影响。
Viscosity: DESs are generally highly viscous at room temperature due to the extensive hydrogen bond network between components. Viscosity is affected by the nature of components, their molar ratio, temperature, and water content. The presence of water significantly reduces viscosity, while increasing conductivity.
粘度:深共熔溶剂在室温下通常具有较高的粘度,这是由于组分之间广泛的氢键网络。粘度受组分的性质、摩尔比、温度和水分含量的影响。水的存在显著降低粘度,同时增加导电性。
Ionic Conductivity: DESs tend to have poor ionic conductivities due to their high viscosity, but this can be improved by increasing temperature or adjusting the hydrogen bond acceptor/donor molar ratio.
离子导电性:深度共混溶剂由于其高粘度,往往具有较差的离子导电性,但通过提高温度或调整氢键受体/供体的摩尔比,可以改善这一点。
Surface Tension: DESs with high viscosity exhibit high surface tensions, reflecting the strength of intermolecular forces between components. Surface tension decreases linearly with increasing temperature and is influenced by the salt mole fraction and cation type.
表面张力:具有高粘度的 DES 表现出高表面张力,反映了组分之间分子间力的强度。表面张力随着温度的升高而线性下降,并受盐摩尔分数和阳离子类型的影响。
Polarity: Polarity is a key property reflecting the solvation capability of DESs. It is often estimated via solvatochromic parameters, considering the shift of UV−vis bands for negatively or positively solvatochromic dyes. Polarity can be probe-dependent and is influenced by water content, which increases dipolarity/polarizability and decreases hydrogen bond basicity.
极性:极性是反映深共溶剂(DESs)溶剂能力的关键属性。通常通过溶剂色谱参数来估计,考虑到负性或正性溶剂色谱染料的紫外-可见光带的位移。极性可能依赖于探针,并受到水分含量的影响,这增加了偶极性/极化率并降低了氢键基本性。
Effect of Water on DESs: The presence of water significantly affects the physicochemical properties of DESs. Water can be absorbed by DESs, which can improve performance in some cases but may also disrupt the supramolecular network of the eutectic mixtures. The impact of water on DESs can lead to a transition from a "water-in-deep eutectic solvent" to a "deep eutectic solvent-in-water" system at certain hydration levels, affecting their structural arrangement and intermolecular interactions.
水对深共熔溶剂的影响:水的存在显著影响深共熔溶剂的物理化学性质。水可以被深共熔溶剂吸收,在某些情况下可以改善性能,但也可能破坏共熔混合物的超分子网络。水对深共熔溶剂的影响可能导致在某些水合水平上,从“水-深共熔溶剂”转变为“深共熔溶剂-水”系统,影响它们的结构排列和分子间相互作用。
In summary, Deep Eutectic Solvents (DESs) present a highly adaptable and adjustable foundation for green chemistry, enabling the customization of their properties to fit specific application needs. Gaining insights into the physicochemical characteristics of DESs, as well as comprehending the influence of water on their structure and behavior, is essential for enhancing their efficacy across diverse industries. This knowledge aids in the strategic utilization of DESs, highlighting the importance of ongoing research to fully exploit their potential and further nudge sustainable chemical processes.
总之,深共熔溶剂(DESs)为绿色化学提供了高度适应和可调的基础,使其属性能够根据特定应用需求进行定制。深入了解 DES 的物理化学特性,以及理解水对其结构和行为的影响,对于提高其在各个行业的有效性至关重要。这些知识有助于战略性地利用 DES,突出持续研究的重要性,以充分发挥其潜力并进一步推动可持续化学过程。
DES的制备方法(直接合成法和其他创新方法)
DES 的制备方法(直接合成法和其他创新方法)
Deep Eutectic Solvents (DES) are a novel class of solvents that have gained significant attention due to their green and sustainable nature. They are formed through the synergistic effect of a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA), which combine at specific molar ratios to produce a eutectic mixture with a melting point significantly lower than either of the individual components.
深共晶溶剂(DES)是一类新型溶剂,由于其绿色和可持续的特性而受到广泛关注。它们是通过氢键供体(HBD)和氢键受体(HBA)的协同作用形成的,二者在特定的摩尔比下结合,产生一种熔点显著低于任一成分的共晶混合物。
The preparation of DES typically involves a straightforward procedure that can be adapted based on the desired application and the nature of the components used. The fabrication of Deep Eutectic Solvents (DES) commences with the selection of a suitable hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA), with common choices being choline chloride, betaine, urea, and glycerol for HBDs, and lactic acid, citric acid, or malonic acid for HBAs. These components are then mixed in a defined molar ratio, typically 1:2, to form the DES. The mixture is subsequently heated to a temperature range of 60–80°C and stirred vigorously to achieve a homogeneous, transparent liquid state, facilitating the formation of a deep eutectic mixture. Optionally, water may be added to adjust the viscosity and enhance the solvation capabilities of the DES. Following preparation, the DES is characterized for its physical properties, including density, viscosity, and melting point, often using techniques such as differential scanning calorimetry (DSC) to confirm the eutectic formation. The resulting DES is then ready for application in various processes, such as extraction procedures, as a reaction medium, or as a solvent for a diverse range of compounds.
深共晶溶剂(DES)的制备通常涉及一个简单的过程,可以根据所需的应用和所使用成分的性质进行调整。 深共晶溶剂(DES)的制备始于选择合适的氢键供体(HBD)和氢键受体(HBA),常见的选择包括氯化胆碱、甜菜碱、尿素和甘油作为 HBD,以及乳酸、柠檬酸或苹果酸作为 HBA。这些成分按照一定的摩尔比(通常为 1:2)混合,以形成 DES。然后,将混合物加热到 60-80°C 的温度范围内,并剧烈搅拌,以达到均匀透明的液态,从而促进深共晶混合物的形成。可选地,添加水以调整粘度并增强 DES 的溶剂能力。准备完成后,DES 的物理性质(包括密度、粘度和熔点)会被表征,通常使用差示扫描量热法(DSC)等技术来确认共晶的形成。 获得的 DES 随后可以应用于各种过程,例如提取程序、作为反应介质或作为多种化合物的溶剂。
The innovative preparation of Deep Eutectic Solvents (DES) is increasingly focusing on sustainability and green chemistry principles. One approach is to utilize natural components as hydrogen bond donors (HBDs) and acceptors (HBAs), extracting them from plant or food waste to form Natural Deep Eutectic Solvents (NaDES). The preparation conditions are optimized by adjusting parameters such as temperature, stirring speed, and reaction time to achieve a DES with reduced viscosity and enhanced performance. Ultrasound and microwave assistance are employed to expedite the interaction between HBDs and HBAs, thus accelerating the formation of DES while conserving energy and time. The exploration of novel HBD-HBA combinations, including the integration with ionic liquids, leads to the development of DES with tailored physicochemical properties to meet specific application requirements. Green and sustainable synthetic pathways are adopted to minimize the generation of harmful by-products, adhering to the principles of atom economy and non-toxic synthesis. The viscosity and solvation capabilities of DES are finely tuned by controlling the water content, as water acts as an effective co-solvent, significantly influencing the DES's physical and chemical properties. Molecular simulation and computational chemistry are leveraged to predict and design the composition and properties of new DES, enabling virtual screening before laboratory synthesis and thus saving time and resources. Biocatalysis and biotransformation offer mild and environmentally friendly methods for DES synthesis. Solid-state synthetic methods are explored to prepare DES, reducing the use of large amounts of organic solvents and decreasing environmental impact. Finally, strategies for the recovery and reuse of DES are developed to reduce chemical waste, enhancing the economics and sustainability of DES use. These innovative methods not only push the frontiers of DES preparation technology but also expand their potential applications across various fields.
深共晶溶剂(DES)的创新制备正越来越关注可持续性和绿色化学原则。一种方法是利用天然成分作为氢键本体(HBD)和氢键接受体(HBA),从植物或食品废料中提取,形成天然深共晶溶剂(NaDES)。通过调整温度、搅拌速度和反应时间等参数来优化制备条件,以获得粘度降低、性能增强的 DES。采用超声波和微波辅助,加速 HBD 和 HBA 之间的相互作用,从而加快 DES 的形成,节约能源和时间。探索新颖的 HBD-HBA 组合,包括与离子液体的结合,有助于开发具有特定物理化学特性的 DES,以满足特定应用需求。采用绿色可持续的合成路径,以尽量减少有害副产品的产生,遵循原子经济性和无毒合成的原则。 通过控制水分含量,可以精细调节深度共溶剂(DES)的粘度和溶解能力,因为水作为有效的共溶剂,显著影响 DES 的物理和化学性质。利用分子模拟和计算化学来预测和设计新 DES 的组成和特性,实现实验室合成前的虚拟筛选,从而节省时间和资源。生物催化和生物转化提供了温和且环保的 DES 合成方法。探索固态合成方法以制备 DES,减少大量有机溶剂的使用,降低环境影响。最后,开发 DES 的回收和再利用策略,以减少化学废物,提高 DES 使用的经济性和可持续性。这些创新方法不仅推动了 DES 制备技术的前沿,也扩大了它们在各个领域的潜在应用。
It's important to note that the choice of HBD and HBA, as well as the molar ratios and any additives, can significantly influence the properties of the DES, making it a versatile and tunable solvent system. The simplicity of the preparation method, coupled with the ability to tailor DES for specific applications
需要注意的是,HBD 和 HBA 的选择,以及摩尔比和任何添加剂,都会显著影响深共熔溶剂(DES)的性质,使其成为一种多功能和可调节的溶剂系统。制备方法的简单性与根据特定应用定制 DES 的能力相结合。
DES在黄酮类化合物提取中的应用
DES 在黄酮类化合物提取中的应用
3.1 DES在不同植物来源的黄酮类化合物提取中的应用
3.1 DES 在不同植物来源的黄酮类化合物提取中的应用
In recent years, Deep Eutectic Solvents (DESs) have emerged as a green alternative for extracting flavonoids from various plant sources, offering a sustainable and efficient approach compared to traditional organic solvents. This review will discuss the application of DESs in the extraction of flavonoids from three different plant sources: Dendrobium officinale, Rhamnus alaternus, and Xanthoceras sorbifolia Bunge.
近年来,深共熔溶剂(DESs)作为提取各种植物来源中黄酮类化合物的绿色替代品,逐渐浮出水面,提供了一种可持续和高效的方法,与传统有机溶剂相比。本文将讨论深共熔溶剂在提取三种不同植物来源的黄酮类化合物中的应用:铁皮石斛、旱柳和花榈木。
Dendrobium officinale
铁皮石斛
Studies have demonstrated that DESs, particularly those based on choline chloride and lactic acid, significantly enhance the extraction yield of flavonoids from Dendrobium officinale stems. The employment of ultrasound-assisted DES extraction has been reported to increase the yield of flavonoids by up to 170% compared to conventional heating methods. This improvement is attributed to the synergistic effect of DESs and ultrasound, which disrupts cell walls and enhances the mass transfer of flavonoids. The DESs not only improve the extraction efficiency but also contribute to the preservation of the bioactivity of the extracted flavonoids.
研究表明,特别是基于氯化胆碱和乳酸的深共熔溶剂(DESs)显著提高了从铁皮石斛茎中提取类黄酮的产率。采用超声辅助的深共熔溶剂提取法,相比于传统加热方法,类黄酮的提取产率最高可提高 170%。这一改善归因于深共熔溶剂和超声的协同作用,它们破坏了细胞壁,增强了类黄酮的物质传递。深共熔溶剂不仅提高了提取效率,还有助于保持提取类黄酮的生物活性。
Rhamnus alaternus
小茴香
Optimization of ultrasound-assisted extraction using DESs composed of choline chloride and glycerol has proven effective for extracting flavonoids from Rhamnus alaternus leaves. The flavonoids extracted using this method have exhibited high antioxidant properties, highlighting the potential of DESs in obtaining high-quality bioactive extracts. The DESs facilitate the extraction process by forming hydrogen bonds with the flavonoids, effectively solubilizing them from the plant matrix. The efficiency of the extraction process is further enhanced by the application of ultrasound, which aids in breaking down the plant cell structure and increasing the contact surface area for extraction.
采用由氯化胆碱和甘油组成的深度共混溶剂(DESs)优化超声辅助提取,已被证明对提取毛榉(Rhamnus alaternus)叶中的类黄酮有效。使用这种方法提取的类黄酮表现出较高的抗氧化特性,突显了 DESs 在获得高质量生物活性提取物方面的潜力。DESs 通过与类黄酮形成氢键,促进了提取过程,有效地将其从植物基质中溶解出来。通过应用超声波,提取过程的效率进一步提高,超声波有助于破坏植物细胞结构,增加提取的接触表面积。
Xanthoceras sorbifolia Bunge
黄花楸 Bunge
The use of natural Deep Eutectic Solvents (NADESs), such as 1,4-butanediol-acetic acid, has been optimized for the extraction of flavonoids from Xanthoceras sorbifolia Bunge. This method has not only improved the extraction yield but also enhanced the antioxidant activity of the flavonoids compared to traditional methanol extraction. The NADESs, derived from natural products, offer a more environmentally friendly approach to extraction, reducing the environmental impact while maintaining high extraction efficiency and product quality. The optimization of the extraction process using response surface methodology further ensures that the extraction conditions are fine-tuned for maximum yield and efficiency.
天然深共熔溶剂(NADESs)的使用,如 1,4-丁二醇-醋酸,已被优化用于从黄花木兰(Xanthoceras sorbifolia Bunge)中提取类黄酮。这种方法不仅提高了提取产率,还增强了类黄酮的抗氧化活性,相较于传统的甲醇提取。源自天然产品的 NADESs 提供了一种更环保的提取方法,减少了对环境的影响,同时保持了高提取效率和产品质量。利用响应面法优化提取过程,进一步确保提取条件经过精细调整,以实现最大产率和效率。
3.2 DES与其他提取技术的联用
3.2 DES 与其他提取技术的联用
Ultrasound-Assisted Extraction (UAE)
超声波辅助提取 (UAE)
The use of ultrasound with DESs has been shown to enhance mass transfer and cell wall disruption, leading to higher yields of bioactive compounds. Ultrasonication creates cavitation bubbles that collapse and generate shear forces, which facilitate the release of compounds from plant matrices. For instance, studies have demonstrated that the combination of ultrasound with DESs, such as choline chloride and lactic acid, significantly increased the extraction of anthocyanins from berries and other fruits.
超声波与深荡液(DESs)的结合已被证明可以增强传质和细胞壁破裂,从而提高生物活性化合物的产量。超声波冲击会产生气蚀泡沫,这些泡沫的崩溃会产生剪切力,从而促进化合物从植物基质中释放。例如,研究表明,超声波与深荡液如氯化胆碱和乳酸的结合显著增加了从浆果和其他水果中提取花青素的效果。
Microwave-Assisted Extraction (MAE)
微波辅助提取 (MAE)
Microwave energy has been effectively combined with DESs to accelerate the extraction process by rapidly heating the solvent and enhancing the solubility of target compounds. This method has been used to extract phenolic compounds from olive leaves and other plant materials, showing improved extraction efficiency compared to conventional solvents.
微波能量已有效地与深电竞争溶剂结合,以通过快速加热溶剂和增强目标化合物的溶解度来加速提取过程。该方法已用于从橄榄叶和其他植物材料中提取酚类化合物,与传统溶剂相比,显示出更高的提取效率。
Pressurized Liquid Extraction (PLE)
加压液体提取 (PLE)
High pressure can enhance the penetration of DESs into plant tissues, leading to faster and more efficient extraction. PLE with DESs has been used to extract bioactive compounds from various plant materials, demonstrating the potential of this combination for industrial-scale applications.
高压可以增强深度共溶剂(DESs)渗透植物组织的能力,从而实现更快、更高效的提取。使用深度共溶剂的加压液体提取(PLE)已被用于从各种植物材料中提取生物活性化合物,展示了这种组合在工业规模应用中的潜力。
High-Speed Homogenization and Cavitation-Burst Extraction (HSH-CBE)
高速均质化与气穴爆发提取 (HSH-CBE)
This method uses high-speed homogenization to disrupt plant cells, followed by cavitation bursts to further enhance the extraction process. The use of DESs in conjunction with HSH-CBE has been shown to be effective for extracting anthocyanins and other phenolic compounds from grape and other fruit by-products.
该方法使用高速均质化来破坏植物细胞,随后通过气穴爆发进一步增强提取过程。与 HSH-CBE 结合使用的深度共溶剂(DESs)已被证明在从葡萄和其他水果副产品中提取花青素和其他酚类化合物方面有效。
Solid-Phase Extraction (SPE)
固相萃取 (SPE)
DESs have been used to pre-treat plant materials, enhancing the binding of target compounds to solid-phase resins. This approach has been used to extract flavonoids from plant extracts, showing higher recovery rates compared to traditional solvents.
DESs 已被用于对植物材料进行预处理,提高靶化合物与固相树脂的结合。这种方法已被用于从植物提取物中提取黄酮类化合物,显示出比传统溶剂更高的回收率。
Enzyme-Assisted Extraction
酶辅助提取
DESs can be used in combination with enzymatic treatments to break down cell walls and increase the availability of bioactive compounds. This method has been applied to extract phenolics from fruits and vegetables, resulting in higher extraction yields and selectivity.
DES 可以与酶处理结合使用,以破坏细胞壁并增加生物活性化合物的可用性。这种方法已被应用于提取水果和蔬菜中的酚类物质,从而获得更高的提取产量和选择性。
3.3 DES提取效果的影响因素
3.3 影响 DES 提取效果的因素
Deep Eutectic Solvents (DESs) are increasingly recognized as effective and sustainable extraction media for various bioactive compounds. Their extraction efficiency is influenced by multiple factors, which can be categorized into solvent composition, physicochemical properties, and extraction conditions.
深共晶溶剂(DESs)越来越被认为是提取各种生物活性化合物的有效和可持续的介质。它们的提取效率受多种因素的影响,这些因素可以分为溶剂成分、物理化学性质和提取条件。
Solvent Composition
溶剂成分
Hydrogen Bond Donor (HBD) and Acceptor (HBA): The type and ratio of HBD and HBA significantly affect the properties of DESs, such as polarity, viscosity, and solubility. Common HBDs include urea, glycerol, and organic acids, while typical HBAs are quaternary ammonium salts like choline chloride.
氢键供体(HBD)和受体(HBA): HBD 和 HBA 的种类和比例显著影响深共混溶剂(DESs)的性质,如极性、粘度和溶解度。常见的 HBD 包括尿素、甘油和有机酸,而典型的 HBA 是象胆碱氯化物这样的铵盐。
Natural DES (NADES): These are derived from natural components like sugars and amino acids, offering enhanced biodegradability and lower toxicity compared to synthetic DES.
天然深层水(NADES): 这些来自天然成分,如糖和氨基酸,提供了比合成深层水更好的生物降解性和更低的毒性.
Physicochemical Properties
物理化学性质
Polarity: DESs can be tailored to match the polarity of target compounds, enhancing extraction efficiency. Polarity is crucial for dissolving and stabilizing various substances.
极性: DES 可以根据目标化合物的极性进行定制,从而提高提取效率。极性对于溶解和稳定各种物质至关重要。
Viscosity and Surface Tension: Lower viscosity and surface tension improve mass transfer and extraction efficiency. Adding water can reduce viscosity but must be optimized to avoid compromising the solvent's properties.
粘度和表面张力: 较低的粘度和表面张力可以提高传质和提取效率。添加水可以降低粘度,但必须进行优化,以避免影响溶剂的性质。
Thermal Stability: DESs exhibit high thermal stability, which is beneficial for extractions requiring elevated temperatures.
热稳定性: 深度溶剂(DESs)表现出高热稳定性,这对需要高温的提取过程是有利的。
Extraction Conditions
提取条件
Temperature and Time: Moderate temperatures and specific extraction times maximize yield. For example, temperatures around 50°C and extraction times of about 20 minutes are often optimal.
温度和时间: 适中的温度和特定的提取时间可以最大化产量。例如,约 50°C 的温度和大约 20 分钟的提取时间通常是最佳的。
Ultrasonic Power: Techniques like ultrasound-assisted extraction (UAE) enhance mass transfer and extraction efficiency. Power settings around 300 W are common.
超声波功率: 超声辅助提取(UAE)等技术可以增强质传递和提取效率。常见的功率设置约为 300 瓦。
Water Content: Optimal water content varies but generally improves mass transfer and reduces viscosity. Typically, around 30% water content is effective.
水分含量: 最佳水分含量因情况而异,但通常可以改善传质并降低黏度。通常,约 30%的水分含量是有效的。
pH: Adjusting the pH can optimize the interaction between DES and the extracted substances, enhancing the extraction process
pH: 调整 pH 值可以优化 DES 与提取物质之间的相互作用,从而增强提取过程
In summary, the extraction efficiency of DESs is influenced by the careful selection of solvent composition, optimization of physicochemical properties, and precise control of extraction conditions. These factors collectively determine the effectiveness of DESs in extracting various bioactive compounds.
总结来说,深共溶剂的提取效率受到溶剂成分的精心选择、物理化学性质的优化以及提取条件的精准控制的影响。这些因素共同决定了深共溶剂在提取各种生物活性化合物中的有效性。
4.针对黄酮类化合物DES的分类和选择
4.针对黄酮类化合物DES 的分类和选择
4.1不同类型的DES提取黄酮类化合物
4.1不同类型的 DES提取黄酮类化合物
Deep eutectic solvents (DESs) have demonstrated their versatility as green solvents in various extraction processes, including the extraction of flavonoids, which are a group of important bioactive compounds with diverse health benefits. The different types of DESs can play distinct roles in the extraction of flavonoids due to their unique properties.
深共熔溶剂(DES)在各种提取过程中展示了作为绿色溶剂的多功能性,包括提取黄酮类化合物,这是一组具有多种健康益处的重要生物活性化合物。不同类型的 DES 因其独特的性质在提取黄酮类化合物时可以发挥不同的作用。
Type I DESs: Composed of non-hydrated metal halides and quaternary ammonium salts, these DESs may not be the first choice for flavonoid extraction due to their high melting points and the difficulty in obtaining the non-hydrated metal halides. However, they can form strong hydrogen bonds, which could potentially be utilized for the extraction of certain flavonoids that require strong interactions for effective extraction.
类型 I 深度共熔溶剂:由非水合金属卤化物和四级铵盐组成,这些深度共熔溶剂可能不是黄酮提取的首选,原因是它们的熔点较高且难以获得非水合金属卤化物。然而,它们可以形成强氢键,这可能被用于提取某些需要强相互作用才能有效提取的黄酮。
Type II DESs: Containing hydrated metal halides, these DESs are more accessible and less expensive, making them more suitable for large-scale extraction processes. Their ability to form hydrogen bonds and their solubility properties can be beneficial for the extraction of flavonoids, particularly those with hydrophilic properties.
II 型深共熔溶剂:含有水合金属卤化物,这些深共熔溶剂更易获得且成本更低,更适合大规模提取过程。它们形成氢键的能力及其溶解性特性对提取类黄酮,特别是那些具有亲水特性的类黄酮,具有积极的作用。
Type III DESs: Formed by quaternary ammonium salts and various hydrogen bond donors (HBDs) such as amides, alcohols, and carboxylic acids, these DESs are the most common in biorefinery processes. Their low viscosity, insensitivity to air/moisture, and ease of biodegradability make them excellent candidates for the extraction of flavonoids. The variety of HBDs allows for the fine-tuning of the solvent's polarity, which is crucial for the efficient extraction of flavonoids with different polarities.
III 型深共熔溶剂:由季铵盐和各种氢键供体(HBDs)如酰胺、醇和羧酸形成,这些深共熔溶剂在生物精炼过程中最为常见。它们的低粘度、对空气/湿气的不敏感性以及易于生物降解的特性使它们成为提取类黄酮的优秀候选者。多样的氢键供体允许对溶剂的极性进行精细调节,这对高效提取不同极性的类黄酮至关重要。
Type IV DESs: Synthesized from metal halides and organic ligands like urea, acetamide, and ethylene glycol, these DESs offer a broader range of possibilities for flavonoid extraction. Their unique structures can provide specific interactions with flavonoid molecules, potentially enhancing the extraction efficiency.
IV 型深共熔溶剂:由金属卤化物和有机配体如尿素、乙酰胺和乙二醇合成,这些深共熔溶剂为类黄酮提取提供了更广泛的可能性。它们独特的结构可以与类黄酮分子产生特定的相互作用,可能提高提取效率。
Type V DESs: Also known as non-ionic DESs, these are formed by mixing compounds that do not necessarily involve ionic species. They are often based on renewable resources and have shown potential in the green synthesis applications. Their ability to dissolve a wide range of compounds makes them suitable for the extraction of flavonoids, which are known for their diverse chemical structures.
V 型深共熔溶剂:也称为非离子深共熔溶剂,这些溶剂是通过混合不一定涉及离子物质的化合物形成的。它们通常基于可再生资源,并在绿色合成应用中显示出潜力。它们能够溶解广泛的化合物,使其适合提取黄酮类化合物,而黄酮类化合物以其多样的化学结构而闻名。
Hydrophobic DESs: Designed to overcome the limitations of water-miscible DESs in liquid samples, hydrophobic DESs have been effectively used in dispersive liquid-liquid microextraction (DLLME) techniques for the extraction of various analytes, including flavonoids, from aqueous solutions. Their hydrophobic nature allows for better interaction with the hydrophobic parts of flavonoid molecules, leading to more efficient extraction.
疏水性深共熔溶剂:为了克服水溶性深共熔溶剂在液体样品中的局限性,疏水性深共熔溶剂已被有效应用于分散液-液微萃取(DLLME)技术中,以提取包括类黄酮在内的各种分析物。它们的疏水特性使其能够更好地与类黄酮分子的疏水部分相互作用,从而实现更高效的提取。
As research progresses, the development of new DESs with tailored properties for the extraction of flavonoids will continue to expand the potential of these green solvents in the field of natural product chemistry.
随着研究的进展,开发具有定制特性的用于提取类黄酮的新型深层沸点溶剂将继续扩大这些绿色溶剂在天然产品化学领域的潜力。
4.2 如何选择适合特定黄酮类化合物提取的DES
4.2 如何选择适合特定黄酮类化合物提取的深度共熔溶剂
To select suitable Deep Eutectic Solvents (DES) for the extraction of specific flavonoid compounds, several factors must be considered.
为了选择适合提取特定黄酮化合物的深共熔溶剂(DES),必须考虑几个因素。
Composition of DES
DES 的组成
DES are typically composed of a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD). Common HBAs include choline chloride, while HBDs can be various organic acids, alcohols, or sugars. The choice of HBA and HBD affects the DES properties such as polarity, viscosity, and extraction efficiency.
DES 通常由氢键受体 (HBA) 和氢键供体 (HBD) 组成。常见的 HBA 包括氯化胆碱,而 HBD 可以是各种有机酸、醇或糖。HBA 和 HBD 的选择会影响 DES 的性质,如极性、粘度和提取效率。
Polarity Matching
极性匹配
The polarity of the DES should match that of the target flavonoid. Flavonoids have varying polarities depending on their structure. For instance, more polar flavonoids like quercetin may require more polar DES, whereas less polar flavonoids might be better extracted with less polar DES. Studies have shown that DES with choline chloride and organic acids (e.g., citric acid) are effective for extracting polar flavonoids.
DES 的极性应与目标类黄酮的极性相匹配。类黄酮的极性因其结构而异。例如,像槲皮素这样的极性较强的类黄酮可能需要更极性的 DES,而极性较弱的类黄酮则可能更适合用极性较弱的 DES 提取。研究表明,含氯化胆碱和有机酸(例如,柠檬酸)的 DES 在提取极性类黄酮方面效果显著.
Viscosity
粘度
High viscosity can hinder the extraction process by limiting mass transfer. Adding water to DES can reduce viscosity and improve extraction efficiency. For example, a DES composed of choline chloride and citric acid with 30% water was found to be effective in extracting flavonoids from soy products. The optimal water content varies but typically ranges from 10% to 30%.
高粘度会通过限制质量传递来阻碍提取过程。向深度共熔溶剂中添加水可以降低粘度并提高提取效率。例如,发现由氯化胆碱和柠檬酸组成的深度共熔溶剂与 30%的水结合在一起,能够有效提取大豆产品中的类黄酮。最佳水分含量因情况而异,但通常在 10%到 30%之间.
Temperature
温度
Temperature influences both the viscosity of DES and the solubility of flavonoids. Higher temperatures generally enhance extraction efficiency by reducing viscosity and increasing solubility. However, very high temperatures can degrade heat-sensitive flavonoids. Optimal extraction temperatures are usually between 25°C and 60°C.
温度影响深度共溶剂的粘度和类黄酮的溶解度。较高的温度通常通过降低粘度和增加溶解度来提高提取效率。然而,过高的温度可能会降解热敏感的类黄酮。最佳提取温度通常在 25°C 到 60°C 之间.
Extraction Time
提取时间
The extraction time should be optimized to balance efficiency and practicality. Longer extraction times can increase yield but may also lead to degradation of flavonoids. Typical extraction times range from 30 minutes to several hours.
提取时间应优化以平衡效率和实用性。较长的提取时间可以提高产量,但也可能导致类黄酮的降解。典型的提取时间范围从 30 分钟到几个小时.
Molecular Interactions
分子相互作用
The interactions between DES components and flavonoids are crucial. DES should form strong hydrogen bonds with flavonoids to enhance solubility. Molecular dynamics and quantum computational studies can help predict these interactions and optimize DES composition.
DES 组件与类黄酮之间的相互作用至关重要。DES 应与类黄酮形成强氢键以增强溶解度。分子动力学和量子计算研究可以帮助预测这些相互作用并优化 DES 成分.
Toxicity and Safety
毒性和安全性
While DES are generally considered safer than conventional solvents, their toxicity should still be evaluated, especially if the extracts are intended for food or pharmaceutical applications. Natural DES (NaDES) composed of biocompatible components like sugars and amino acids are preferable for such applications.
虽然深度共溶剂(DES)通常被认为比传统溶剂更安全,但其毒性仍需评估,特别是当提取物用于食品或药品应用时。由糖和氨基酸等生物相容成分组成的天然深度共溶剂(NaDES)更适合此类应用。
Environmental Impact
环境影响
DES should align with green chemistry principles, being biodegradable and derived from renewable resources. This makes them a sustainable alternative to traditional organic solvents
DES 应该与绿色化学原则相一致,具有生物降解性并来源于可再生资源。这使它们成为传统有机溶剂的可持续替代品。
Specific Examples
具体示例
Choline chloride and citric acid: Effective for extracting isoflavones from soy products.
氯化胆碱和柠檬酸:有效提取大豆产品中的异黄酮.
Choline chloride and lactic acid: Used for extracting flavonoids from Moringa oleifera leaves.
氯化胆碱和乳酸:用于从辣木叶中提取类黄酮。
Choline chloride and glycolic acid: Demonstrated good solubility for licorice flavonoids.
氯化胆碱和甘醇酸:显示出对甘草黄酮的良好溶解性.
Selecting the appropriate DES for flavonoid extraction involves considering the polarity, viscosity, temperature, molecular interactions, and environmental impact. By optimizing these factors, DES can provide an efficient, safe, and sustainable method for extracting valuable flavonoids from various plant sources.
选择适合的深度共熔溶剂(DES)用于黄酮提取时,需要考虑极性、粘度、温度、分子相互作用和环境影响。通过优化这些因素,深度共熔溶剂可以提供一种高效、安全和可持续的方法,从各种植物来源中提取有价值的黄酮。
4.3DES提取黄酮类化合物的绿色化学优势
4.3 DES 提取黄酮类化合物的绿色化学优势
Deep Eutectic Solvents (DES) embody a significant stride forward in the realm of green chemistry, particularly in the extraction of flavonoids, which are valuable plant secondary metabolites with numerous health benefits. The composition of DES is inherently sustainable, drawing on renewable and natural precursors such as choline chloride, urea, glycerol, and a variety of organic acids. These components are sourced from abundant and sustainable resources, thereby diminishing dependence on petrochemical-derived solvents and aligning with the core tenets of green chemistry.
深共熔溶剂(DES)在绿色化学领域中代表了一项重要的进展,特别是在提取类黄酮方面,类黄酮是具有众多健康益处的宝贵植物次级代谢物。DES 的组成本质上是可持续的,采用可再生和天然前体,如氯化胆碱、尿素、甘油和各种有机酸。这些成分来自丰富且可持续的资源,从而减少了对石化衍生溶剂的依赖,并与绿色化学的核心原则相一致。
A key attribute of many DES is their biodegradability, which allows them to break down into harmless components through microbial action. This characteristic is pivotal for mitigating environmental persistence and potential ecological harm, thereby shrinking the industrial footprint. Moreover, DES, especially those formulated from natural components, generally present low toxicity, a crucial factor for safeguarding both worker health and environmental integrity by minimizing the risk of adverse effects on living organisms.
许多深度共晶(DES)的一个关键特性是其生物降解性,这使它们能够通过微生物作用分解为无害成分。这个特性对于减轻环境持久性和潜在生态危害至关重要,从而缩小工业足迹。此外,特别是那些由天然成分配制的深度共晶,通常表现出低毒性,这是保护工人健康和环境完整性的关键因素,因为它可以最小化对生物体的不良影响风险。
In contrast to traditional solvents, which can be hazardous, volatile, and environmentally persistent, DES offer a greener alternative that can either replace or reduce reliance on these deleterious solvents. This shift contributes to a reduction in the use of organic solvents, leading to a decrease in the extraction process's environmental impact.
与传统溶剂相比,传统溶剂可能是有害的、挥发性的,并且在环境中持久存在,深度共溶剂提供了一种更环保的替代方案,可以替代或减少对这些有害溶剂的依赖。这一转变有助于减少有机溶剂的使用,从而降低提取过程对环境的影响。
The efficiency of flavonoid extraction is markedly enhanced with DES, which can dissolve a broad spectrum of compounds, including those of varying polarities, thanks to their adjustable nature. This tunability results in higher extraction yields and potentially streamlined extraction procedures, conserving time and resources.
使用深度共熔溶剂(DES)显著提高了类黄酮的提取效率,因为它们能够溶解广泛的化合物,包括不同极性的化合物,这得益于其可调节的特性。这种可调性导致更高的提取产率,并可能简化提取过程,从而节省时间和资源。
The viscosity of DES is temperature-dependent, an attribute that can be leveraged to facilitate extraction processes. As the temperature increases, the viscosity of DES decreases, endowing them with improved capabilities to penetrate plant matrices and extract target compounds with greater efficiency.
DES 的粘度依赖于温度,这一特性可以被利用来促进提取过程。随着温度的升高,DES 的粘度降低,使其更有效地渗透植物基质并提取目标化合物。
One of the most notable features of DES is their tunability and design flexibility. By simply adjusting the ratio of hydrogen bond donors (HBDs) to hydrogen bond acceptors (HBAs), DES can be customized to meet specific extraction requirements. This adaptability enables the creation of DES with tailored properties such as polarity, viscosity, and solvation capabilities, optimizing the extraction of特定flavonoids.After extraction, DES can often be recovered and reused, which not only reduces waste but also lessens the necessity for fresh solvents. This recovery is particularly significant in industrial settings where the reuse of solvents can lead to substantial economic and environmental savings.
深度溶剂(DES)最显著的特点之一是其可调性和设计灵活性。通过简单地调整氢键供体(HBDs)与氢键受体(HBAs)的比例,可以定制 DES 以满足特定的提取要求。这种适应性使得可以创建具有特定性质的 DES,如极性、粘度和溶解能力,从而优化特定类黄酮的提取。在提取后,DES 通常可以被回收和重复使用,这不仅减少了废物,还降低了对新溶剂的需求。这种回收在工业环境中尤为重要,因为溶剂的重复使用可以带来可观的经济和环境效益。
Furthermore, DES are compatible with eco-friendly extraction techniques like ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE). The synergy between DES and these techniques can significantly boost extraction efficiency, further minimizing energy consumption and the extraction process's environmental impact.
此外,深度共熔溶剂(DES)与环保提取技术如超声波辅助提取(UAE)和微波辅助提取(MAE)兼容。DES 与这些技术的协同作用可以显著提高提取效率,进一步减少能耗和提取过程对环境的影响。
Beyond extraction, DES can serve as effective media for direct analysis, synthesis, or catalysis, showcasing their versatility and reducing the need for additional solvents or steps in the processing of extracted flavonoids. This wide scope of applications underscores the multifaceted utility of DES in green chemistry.
除了提取,深度共溶剂(DES)还可以作为直接分析、合成或催化的有效介质,展示其多功能性,并减少在提取类黄酮加工中对额外溶剂或步骤的需求。这一广泛的应用范围突显了深度共溶剂在绿色化学中的多方面实用性。
In conclusion, the utilization of DES in flavonoid extraction epitomizes a substantial advancement in green chemistry, offering a sustainable and environmentally benign approach to the extraction and application of valuable natural compounds. Their renewable nature, biodegradability, low toxicity, and tunable properties position DES as an attractive alternative to conventional solvents, fostering a more sustainable trajectory for the extraction and utilization of flavonoids and other natural products.
总之,深度共溶剂在黄酮提取中的应用体现了绿色化学的重大进展,提供了一种可持续和环保的方法来提取和应用有价值的天然化合物。它们的可再生特性、生物降解性、低毒性和可调性质使深度共溶剂成为传统溶剂的有吸引力的替代品,促进了黄酮和其他天然产品提取和利用的更可持续发展。
5.DES在黄酮类化合物提取中的未来应用和发展方向
5.DES 在黄酮类化合物提取中的未来应用和发展方向
Deep eutectic solvents (DESs) have emerged as a promising alternative to traditional organic solvents in the extraction of flavonoids, which are a group of naturally occurring compounds known for their antioxidant and bioactive properties. The future application and development directions of DESs in flavonoid extraction are multifaceted, reflecting the versatility and green chemistry principles associated with these solvents.
深共熔溶剂(DESs)已成为提取类黄酮的传统有机溶剂的有前景的替代品,类黄酮是一类以其抗氧化和生物活性特性而闻名的天然化合物。DESs 在类黄酮提取中的未来应用和发展方向是多方面的,反映了与这些溶剂相关的多功能性和绿色化学原则。
Research has shown that DESs can effectively extract flavonoids from a variety of plant materials. For instance, choline chloride-based DESs have been used to extract flavonoids from apple leaves, with higher extraction rates compared to traditional solvents like methanol and ethanol . Additionally, the extraction process can be further enhanced by employing techniques such as ultrasound assistance, which can disrupt plant cell walls and improve the accessibility of flavonoids to the solvent.
研究表明,深度共熔溶剂(DESs)可以有效地从多种植物材料中提取类黄酮。例如,基于氯化胆碱的深度共熔溶剂已被用于从苹果叶中提取类黄酮,其提取率高于传统溶剂如甲醇和乙醇。此外,通过采用超声辅助等技术,可以进一步增强提取过程,这可以破坏植物细胞壁,提高类黄酮对溶剂的可及性.
The future development of DESs in flavonoid extraction is likely to focus on several key areas. First, there is a need for a deeper understanding of the interactions between DESs and flavonoids at the molecular level. Computational methods and molecular dynamics simulations can provide insights into these interactions, which can inform the design of more effective DES formulations.
在类黄酮提取中,深度共溶剂(DES)的未来发展可能会集中在几个关键领域。首先,需要更深入地了解深度共溶剂与类黄酮在分子层面的相互作用。计算方法和分子动力学模拟可以提供对这些相互作用的洞察,从而为设计更有效的深度共溶剂配方提供信息.
Second, the scalability of DES extraction processes to an industrial level is an important consideration. While laboratory-scale extractions have been successful, translating these methods to larger-scale operations requires overcoming challenges related to viscosity, phase separation, and the high cost of some DES components.
其次,DES 提取过程在工业水平上的可扩展性是一个重要考虑因素。虽然实验室规模的提取已经成功,但将这些方法转化为大规模操作需要克服与粘度、相分离以及某些 DES 成分的高成本相关的挑战。
Third, the development of more sustainable and cost-effective DES formulations is crucial. Research is ongoing to identify natural and abundant HBDs and HBAs that can be used to create DESs with the desired physicochemical properties while minimizing environmental impact and cost.
第三,开发更可持续和具有成本效益的深度共混物(DES)配方至关重要。研究正在进行,以识别可以用于创建具有所需物理化学性质的 DES 的天然和丰富的氢键供体(HBD)和氢键受体(HBA),同时最小化对环境的影响和成本。
Finally, the integration of DES extraction with other green chemistry processes, such as biodegradable solvent recovery and recycling, will be essential for the sustainable use of these solvents in flavonoid extraction . This will not only reduce waste but also contribute to the circular economy by reusing materials and reducing the reliance on virgin resources.
最后,DES 提取与其他绿色化学过程的结合,例如生物可降解溶剂的回收和再利用,对于在黄酮提取中可持续使用这些溶剂至关重要。这不仅会减少废物,还将通过重复使用材料和减少对原材料的依赖,促进循环经济的发展。
In conclusion, the future of DESs in flavonoid extraction is poised for growth, with a focus on enhancing extraction efficiency, scaling up processes, developing more sustainable formulations, and integrating with other green chemistry practices. These developments will further establish DESs as a key component in the green extraction of bioactive compounds from natural sources.
总之,深度共溶剂在类黄酮提取中的未来有望增长,重点在于提高提取效率、扩大工艺规模、开发更可持续的配方以及与其他绿色化学实践相结合。这些发展将进一步确立深度共溶剂作为从自然来源提取生物活性化合物的绿色提取中的关键组成部分。