To establish an environment-friendly extraction method of limonoids from citrus seeds, 13 natural deep eutectic solvents were prepared and their physical and chemical properties were tested. The ultrasonic-assisted extraction method was used to extract limonoids from citrus seeds, and three main limonoids (limonoid, nomilin, and phellodendron ketone) were determined by ultra-performance liquid chromatography. Compared with the traditional ethanol solvent (the volume fraction was 80%), the natural deep eutectic solvents composed of choline chloride and formic acid (the molar ratio was 1∶4) had better extraction efficiency. On this basis, the response surface method was used to optimize the water contents, solid-liquid ratio, extraction temperature, extraction time, and extraction temperature. As a consequence, the best extraction condition was the water content of 12% (v/v), the liquid-solid ratio of 10 (mL∶g), the extraction temperature of 60 ℃, and the extraction time of 34 min. The yield of limonin was 13.87 mg/g. This study showed that the prepared natural eutectic solvent could be used as an alternative solvent for extracting limonoids from citrus seeds, which provided some references for further application of natural deep eutectic solvents to extract bioactive compounds from natural products.
[1] MAHATO N, SHARMA K, SINHA M, et al.Bio-sorbents, industrially important chemicals and novel materials from citrus processing waste as a sustainable and renewable bioresource:A review[J].Journal of Advanced Research, 2020, 23:61-82.
[2] SHI Y S, ZHANG Y, LI H T, et al.Limonoids from citrus:Chemistry, anti-tumor potential, and other bioactivities[J].Journal of Functional Foods, 2020, 75:104213.
[3] GUALDANI R, CAVALLUZZI M M, LENTINI G, et al.The chemistry and pharmacology of citrus limonoids[J].Molecules, 2016, 21(11):1530.
[4] QIN S, LV C H, WANG Q S, et al.Extraction, identification, and antioxidant property evaluation of limonin from pummelo seeds[J].Animal Nutrition, 2018, 4(3):281-287.
[5] VIKRAM A, JAYAPRAKASHA G K, PATIL B S.Simultaneous determination of citrus limonoid aglycones and glucosides by high performance liquid chromatography[J].Analytica Chimica Acta, 2007, 590(2):180-186.
[6] YU H, WANG C, DENG S T, et al.Optimization of ultrasonic-assisted extraction and UPLC-TOF/MS analysis of limonoids from lemon seed[J].LWT, 2017, 84:135-142.
[7] DE PAULA J A M, BRITO L F, CAETANO K L F N, et al.Ultrasound-assisted extraction of azadirachtin from dried entire fruits of Azadirachta indica A.Juss.(Meliaceae) and its determination by a validated HPLC-PDA method[J].Talanta, 2016, 149:77-84.
[8] NANA O, MOMENI J, BOYOM F F, et al.Microwave-assisted extraction as an advanced technique for optimisation of limonoid yields and antioxidant potential from Trichilia roka (Meliaceae)[J].Current Research in Green and Sustainable Chemistry, 2021, 4:100147.
[9] SUTTIARPORN P, CHOOMMONGKOL V.Microwave-assisted improved extraction and purification of anticancer nimbolide from Azadirachta indica (neem) leaves[J].Molecules, 2020, 25(12):2913.
[10] GÓMEZ-URIOS C, VIÑAS-OSPINO A, PUCHADES-COLERA P, et al.Sustainable development and storage stability of orange by-products extract using natural deep eutectic solvents[J].Foods, 2022, 11(16):2457.
[11] ABBOTT A P, CAPPER G, DAVIES D L, et al.Novel solvent properties of choline chloride/urea mixtures[J].Chemical Communications, 2003(1):70-71.
[12] ZUO J L, MA P R, GENG S Q, et al.Optimization of the extraction process of flavonoids from Trollius ledebouri with natural deep eutectic solvents[J].Journal of Separation Science, 2022, 45(3):717-727.
[13] ZUO J L, GENG S Q, KONG Y Z, et al.Current progress in natural deep eutectic solvents for the extraction of active components from plants[J].Critical Reviews in Analytical Chemistry, 2023, 53(1):177-198.
[14] QIN H, HU X T, WANG J W, et al.Overview of acidic deep eutectic solvents on synthesis, properties and applications[J].Green Energy & Environment, 2020, 5(1):8-21.
[15] JURIĆ T, MIĆIĆ N, POTKONJAK A, et al.The evaluation of phenolic content, in vitro antioxidant and antibacterial activity of Mentha piperita extracts obtained by natural deep eutectic solvents[J].Food Chemistry, 2021, 362:130226.
[16] ZHANG H L, HAO F L, YAO Z F, et al.Efficient extraction of flavonoids from Polygonatum sibiricum using a deep eutectic solvent as a green extraction solvent[J].Microchemical Journal, 2022, 175:107168.
[17] JIANG Z M, WANG L J, GAO Z, et al.Green and efficient extraction of different types of bioactive alkaloids using deep eutectic solvents[J].Microchemical Journal, 2019, 145:345-353.
[18] ZHANG W D, CHENG S B, ZHAI X N, et al.Green and efficient extraction of polysaccharides from Poria cocos F.A.wolf by deep eutectic solvent[J].Natural Product Communications, 2020, 15(2):1-10.
[19] DA SILVA D T, PAULETTO R, DA SILVA CAVALHEIRO S, et al.Natural deep eutectic solvents as a biocompatible tool for the extraction of blueberry anthocyanins[J].Journal of Food Composition and Analysis, 2020, 89:103470.
[20] 何瑞阳, 王锋, 苏小军, 等.玉竹多糖低共熔溶剂提取工艺优化及其抗氧化和抗糖基化活性研究[J].食品与发酵工业, 2022, 48(8):190-198.
HE R Y, WANG F, SU X J, et al.Optimization of extraction process of Polygonatum odoratum polysaccharide by deep eutectic solvent and its antioxidant and anti glycosylation activities[J].Food and Fermentation Industries, 2022, 48(8):190-198.
[21] 伏琳玥, 刘学.基于低共熔溶剂分离黑种草子油中抗氧化活性物质[J].中国油脂, 2021, 46(11):44-49.
FU L Y, LIU X.Separation of antioxidant activity components from black cumin seed oil by deep eutectic solvents[J].China Oils and Fats, 2021, 46(11):44-49.
[22] 孟鹏, 郑宝东.超高效液相色谱法快速并同时检测金柑中柠檬苦素和诺米林[J].中国食品学报, 2013, 13(2):177-181.
MENG P, ZHENG B D.Study on rapid simultaneous determination of limonin and nomilin in kumquat using ultra-performance liquid chromatography[J].Journal of Chinese Institute of Food Science and Technology, 2013, 13(2):177-181.
[23] WANG J Q, JING W Q, TIAN H Y, et al.Investigation of deep eutectic solvent-based microwave-assisted extraction and efficient recovery of natural products[J].ACS Sustainable Chemistry & Engineering, 2020, 8(32):12080-12088.
[24] HUANG S J, DONG T T, XIONG B, et al.Variation in the content and composition of limonoids in fruits of four pomelo varieties during fruit development:The natural debittering process in pomelo fruits[J].Journal of Food Composition and Analysis, 2021, 100:103928.
