Identification of Major Flavone C-Glycosides and Their Optimized Extraction from Cymbidium kanran Using Deep Eutectic Solvents

Abstract

Cymbidium kanran, an orchid exclusively distributed in Northeast Asia, has been highly valued as a decorative plant and traditional herbal medicine. Here, C. kanran extracts were prepared in 70% aqueous methanol using ultrasound-assisted extraction (UAE) and subjected to liquid chromatography-photodiode array detection and ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry analysis, which were used for quantitative and qualitative analysis, respectively. It was found that the extracts were rich in flavone C-glycosides including vicenin-2, vicenin-3, schaftoside, vitexin, and isovitexin. Ten deep eutectic solvents (DESs) were synthesized by combining choline chloride (hydrogen bond acceptor) with various polyols and diols (hydrogen bond donors) and were tested as a medium for the efficient production of extracts enriched with potentially bioactive flavone C-glycosides from C. kanran. A DES named ChCl:DPG, composed of choline chloride and dipropylene glycol at a 1:4 molar ratio, exhibited the best extraction yields. Then, the effects of extraction conditions on the extraction efficiency were investigated by response surface methodology. Lower water content in the extraction solvent and longer extraction time during UAE were desirable for higher extraction yields. Under the statistically optimized conditions, in which 100 mg of C. kanran powder were extracted in 0.53 mL of a mixture of ChCl:DPG and water (74:26, w/w) for 86 min, a total of 3.441 mg g−1 flavone C-glycosides including 1.933 mg g−1 vicenin-2 was obtained. This total yield was 196%, 131%, and 71% more than those obtained using 100% methanol, water, and 70% methanol, respectively.

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

“…This level lies between 75 and 80% (w/v) found for polyphenol extraction with DES from M. oleifera leaves [23,34], and 78 and 80% (w/v) from olive leaves [21,35]. Other investigations reported 80% (w/w) for tartary buckwheat hull [36], 80% (w/w) for sea buckthorn leaves [37], 74% (w/w) for Cymbidium kanran [38] and 76.2% (w/w) for grape skin [39]. In all these optimization studies, the appropriate adjustment of water amount was shown to be critical for the extraction efficiency, because the DES/water proportion regulates features such as viscosity and polarity [40], which profoundly affect solute solubility, hence extraction performance.…”

Optimized Extraction of Glycosylated Flavonoids from Pepper (Capsicum annuum L.) Agricultural Biomass Residues through Ultrasonic Pulse-Assisted Natural Deep Eutectic Solvents

“…Yoo et al 43 used ChCl/1,6-hexanediol 1:7 molar with 32.5 wt % of water to extract phenolic compounds from coffee beans, where the best process conditions were an extraction temperature of 60 °C for 10 min assisted by ultrasound. In another work, Jeong et al 59 optimized the extraction of Cglycosylated flavones from Cymbidium kanran. For instance, Cui et al 60 optimize the extraction of genistin, genistein, and apigenin from pigeon pea roots.…”

Computer-aided solvent screening for the fractionation of wet microalgae biomass

“…Duplicate solvents were deleted. In this screening, 178 pairs of DESs 48,[86][87][88][89][90][91][92][93][94][95] and 143 commercially avialable IL pairs 96,97 were added to the search space, leading to a total of 8011 molecules defining the solvent search space. A complete list of screened solvents can be found in the ESI † .…”