Ionic Liquid-Based Ultrasonic-Assisted Extraction of Forsythosides from the Leaf of Forsythia suspensa (Thunb.) Vahl and Subsequent Separation and Purification by High-Speed Counter-Current Chromatography

Optimisation of the Extraction Process of Naringin and Its Effect on Reducing Blood Lipid Levels In Vitro

The naringin extraction process was optimised using response surface methodology (RSM). A central component design was adopted, which included four parameters: extraction temperature (X₁), material-liquid ratio (X₂), extraction time (X₃), and ultrasonic frequency (X₄) of 74.79 °C, 1.58 h, 1:56.51 g/mL, and 28.05 KHz, respectively. Based on these optimal extraction conditions, naringin was tested to verify the model's accuracy. Naringin yield was 36.2502 mg/g, which was equivalent to the predicted yield of 36.0124 mg/g. DM101 macroporous adsorption resin was used to purify naringin. The effects of loading concentration, loading flow rate, and sample pH on the adsorption rate of naringin and the effect of ethanol concentration on the desorption rate of naringin were investigated. The optimum conditions for naringin purification using macroporous resins were determined. The optimal loading concentration, sample solution pH, and loading flow rate were 0.075 mg/mL, 3.5, and 1.5 mL/min, respectively. Three parallel tests were conducted under these conditions, and the average naringin yield was 77.5643%. Naringin's structure was identified using infrared spectroscopy and nuclear magnetic resonance. In vitro determination of the lipid-lowering activity of naringin was also conducted. These results showed that naringin has potential applications as a functional food for lowering blood lipid levels.

Optimization of Ultrasonic-Assisted Simultaneous Extraction of Three Active Compounds from the Fruits of Forsythia suspensa and Comparison with Conventional Extraction Methods

An efficient ultrasonic-assisted extraction (UAE) method was developed for simultaneous extraction of three active compounds, forsythiaside A (FSA), phillyrin (PHI) and rutin (RT), from the fruits of Forsythia suspensa. The effects of various factors including a binary mixed solvent of methanol/water and ethanol/water, the pH of the solvent, particle size, temperature, solvent to material ratio, ultrasonic input power and extraction time on UAE were investigated in detail. The mass transfer mechanism of UAE using different mixed solvents was further explained by comparison with the maceration extraction method. The response surface methodology was used to optimize the experimental variables including ethanol concentration, solvent to material ratio and extraction time. The optimized conditions for the simultaneous extraction of RT, FSA and PHI were: particle size 60–80 mesh, temperature 30 °C, ultrasonic power 200 W, ethanol concentration 50%, solvent to material ratio 32 mL/g and extraction time 37 min. Compared to conventional extraction methods, UAE provided the highest extraction efficiency and offered many advantages including the reduction of solvent, temperature and time for extraction.

3-(2-Bromoacetamido)-N-(9-ethyl-9H)-carbazol fluorescent probe and its application for the determination of thiophenols in rubber products by HPLC with fluorescence detection and atmospheric chemical ionization mass spectrometry identification

A rapid, sensitive, and selective precolumn derivatization method for the simultaneous determination of eight thiophenols using 3-(2-bromoacetamido)-N-(9-ethyl-9H)-carbazol as a labeling reagent by high-performance liquid chromatography with fluorescence detection has been developed. The labeling reagent reacted with thiophenols at 50°C for 50 min in aqueous acetonitrile in the presence of borate buffer (0.10 mol/L, pH 11.2) to give high yields of thiophenol derivatives. The derivatives were identified by online postcolumn mass spectrometry. The collision-induced dissociation spectra for thiophenol derivatives gave the corresponding specific fragment ions at m/z 251.3, 223.3, 210.9, 195.8, and 181.9. At the same time, derivatives exhibited intense fluorescence with an excitation maximum at λ_ex = 276 nm and an emission maximum at λ_em = 385 nm. Excellent linear responses were observed for all analytes over the range of 0.033-6.66 μmol/L with correlation coefficients of more than 0.9997. Detection limits were in the range of 0.94-5.77 μg/L with relative standard deviations of less than 4.54%. The feasibility of derivatization allowed the development of a rapid and highly sensitive method for the quantitative analysis of trace levels of thiophenols from some rubber products. The average recoveries (n = 3) were in the range of 87.21-101.12%.