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A novel method has been established for the rapid separation and determination of free fatty acids from 37 different varieties of raspberry. In this study, a new fluorescent labeling reagent for fatty acids, 2-(4-amino)-phenyl-1-hydrogen-phenanthrene [9, 10-d] imidazole (PIA), has been synthesized and successfully applied to the high-performance liquid chromatography (HPLC) determination of fatty acids in raspberry. The novel method has been optimized by HPLC with fluorescence detection and online mass spectrometry identification (HPLC-FLD-MS/MS). The 22 main fatty acids (FAs) present in raspberry were derivatized by PIA and separated on a reversed-phase Hypersil GOLD column with gradient elution. The main experimental parameters affecting extraction efficiency and derivatization yield were investigated and optimized by response surface methodology (RSM) combined with Box-Behnken design (BBD). Under the optimum conditions, the method was successfully applied for the analysis of 22 fatty acids in 37 different varieties of raspberry. Good linear correlations were observed for all fatty acids with correlation coefficients of > 0.9978. Limits of detection and quantification (LOD and LOQ) were in the range of 0.12 to 0.49 ng/mL and 1.07 to 2.81 ng/mL, respectively. Furthermore, the results indicated that the raspberries were rich in fatty acids, but the contents of the fatty acids varied among the different varieties.

In this work, we have developed an efficient method for the rapid extraction and separation of triterpene acids from 37 different varieties of raspberry via ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME). The triterpene acids were then determined by high-performance liquid chromatography (HPLC) with fluorescence detection using benzimidazo-[2,1-b]quinazolin-12(6H)-one-5-ethyl-p-toluenesulfonate (BQETS) as the labeling agent. Five triterpene acids, including asiatic acid (AA), maslinic acid (MA), corosolic acid (CA), oleanolic acid (OA) and betulinic acid (BA), were extracted by UA-DLLME using chloroform and acetone as the extracting and dispersing solvents, respectively. After extraction and nitrogen flushing, the extracts were simultaneously characterized by HPLC based on pre-column derivatization using BQETS, a new labeling agent synthesized in our laboratory. Several key parameters affecting the extraction efficiency and derivatization yields were investigated and optimized by response surface methodology (RSM) combined with Box-Behnken design (BBD). The method was further validated for linearity (correlation coefficient <i>R</i> <sup>2</sup> > 0.9979), precision (RSD = 0.23-2.45 %), and recovery (RSD = 90-106.5 %). The limits of detection (LODs) and the limits of quantification (LOQs) were determined to be within the range of 1.83-7.69 µg/L and 6.06-25.47 µg/L, respectively. This is the first report of the use of BQETS as a pre-column derivatization agent for the determination of triterpene acids in real samples. The proposed method has been applied to the determination of five triterpene acids in 37 different raspberry varieties with significantly increased sensitivity compared to other methods. The results obtained indicate that the contents of triterpene acids vary significantly across different raspberry varieties.

Fenugreek is a well known annual herb widely used in both medicine and food. Four flavonoid glycosides have been separated from fenugreek seeds in our previous study. In this study, the effects of the four flavonoid glycosides on regulating glycolipid metabolism and improving mitochondrial function were investigated. Isoorientin showed a very significant activity among these flavonoid glycosides. First, isoorientin decreased the accumulation of lipid droplets in 3T3-L1 preadipocytes by reducing the expression of adipokines including PPARγ, C/EBPα, and FAS. Second, isoorientin restored insulin-stimulated glucose uptake in dexamethasone-induced insulin-resistant 3T3-L1 adipocytes by reactivating Akt and AMPK. Finally, isoorientin improved mitochondrial dysfunction induced by dexamethasone in 3T3-L1 adipocytes. Isoorientin also reversed dexamethasone-induced decrease in mitochondrial membrane potential (MMP) and intracellular ATP production, reduced accumulation of intracellular reactive oxygen species (ROS), and protected mitochondrial DNA (mtDNA) from oxidative damage. At the same time, mitochondrial biogenesis is promoted. Therefore, isoorientin may be an attractive candidate as a glucose-lowering and insulin-resistance-improving agent for the treatment of diabetes.

Amino acids are indispensable components of living organisms. The high amino acid content in Nitraria tangutorum Bobr. fruit distinguishes it from other berry plants and is of great significance to its nutritional value. Herein, using 10-ethyl-acridine-3-sulfonyl chloride as a fluorescent pre-column labeling reagent, a method for the efficient and rapid determination of amino acid content in N. tangutorum by pre-column fluorescence derivatization and on-line mass spectrometry was established and further validated. The limits of detection (signal-to-noise ratio = 3) were between 0.13 and 1.13 nmol/L, with a linear coefficient greater than 0.997 and a relative standard deviation between 1.37% and 2.64%. In addition, the method required a short analysis time, separating 19 amino acids within 20 min. Subsequently, the method was used to analyze the amino acid content of Nitraria tangutorum Bobr. from tissues retrieved from seven regions of the Qinghai-Tibet Plateau. Nitraria tangutorum Bobr. was shown to contain a large amount of amino acids, with the total content and main amino acid varying between the different tissues. This research supports the nutritional evaluation, quality control, and development and utilization of Nitraria tangutorum Bobr.