In situ antioxidation-assisted matrix solid-phase dispersion microextraction and discrimination of chiral flavonoids from citrus fruit via ion mobility quadrupole time-of-flight high-resolution mass spectrometry

A simple and sensitive in situ antioxidation process assisted with a matrix solid-phase dispersion method for extracting chiral flavonoids in citrus fruit was established, and samples were further analyzed using ion mobility quadrupole time-of-flight high-resolution mass spectrometry. The collision cross-sections of the target compounds were studied using single-field and stepped-field methods. The optimal conditions were obtained using 30 mg of C₁₈ as a dispersant, methanol as an elution solvent and 0.6 mM 1,1-diphenyl-2-picrylhydrazyl (DPPH) as a radical solution. Additionally, the method showed satisfactory limits of detection (3.70-6.52 ng/mL) and good recoveries (96.78-104.67%) for four flavonoids in citrus fruit. The IC₅₀ values of DPPH radical-scavenging activities ranged from 817.8 to 981.55 μg/mL for tested samples. The method was a good alternative for the microextraction and determination of antioxidant capacity and chiral differentiation of narirutin, naringin, hesperidin and neohesperidin in citrus fruit.

"Quantity-effect" research strategy for comparison of antioxidant activity and quality of Rehmanniae Radix and Rehmannia Radix Praeparata by on-line HPLC-UV-ABTS assay

Background

Quantitation analysis and chromatographic fingerprint of multi-components are frequently used to evaluate quality of herbal medicines but fail to reveal activity of the components. It is necessary to develop a rational approach of chromatography coupled with activity detection for quality assessment of herbal medicines.

Methods

An on-line HPLC-ultraviolet detection-2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radical scavenging (HPLC-UV-ABTS) method was developed to obtain the chromatographic fingerprints and ABTS^+• inhibition profiles (active fingerprints) of Rehmanniae Radix (Dihuang) and Rehmannia Radix Praeparata (Shu Dihuang). Eighteen compounds showing ABTS^+• inhibition activity were identified by HPLC-fourier-transform mass spectrometry (HPLC-FTMS). Verbascoside was used as a positive control to evaluate the total activities of the samples and the contribution rate of each compound. The similarities of the chromatographic and active fingerprints were estimated by the vectorial angle cosine method.

Results

The results showed that the HPLC-UV-ABTS method could efficiently detect antioxidant activity of the herbal medicine samples. The antioxidants were different between the two herbs and several new antioxidants were identified in Shu Dihuang. A function equation was generated in terms of the negative peak area (x) and the concentrations of verbascoside (y, μg/mL), y = 2E-07 × ⁴ - 8E-05 × ³ + 0.0079 × ² + 0.5755x + 1.4754, R² = 1. Iridoid glycosides were identified as main antioxidants and showed their higher contributions to the total activity of the samples. The total contributions of the three main active components in the Dihuang and Shu Dihuang samples to the total activity, such as echinacoside, verbascoside and an unknown compound, were 39.2–58.1% and 55.9–69.4%, respectively. The potencies of the main active components in the Shu Dihuang samples were two to ten times those in the Dihuang samples. Similarity values for S12 in the chromatographic fingerprints and S03, S12 and P03 in the active fingerprints were less than 0.9. The three batches of samples might show their different quality with the other samples.

Conclusions

The results suggested that the combination of “quantity-effect” research strategy and the HPLC-UV-ABTS analysis method could comprehensively evaluate the active components and quality of Dihuang and Shu Dhuang.

Antagonistic Effect of Cuscuta chinensis on a Rat Model with Unilateral Cryptorchidism

BACKGROUND The aim of this study was to investigate the effect of Cuscuta chinensis Lam. on germ cell apoptosis in a rat model of unilateral cryptorchidism. MATERIAL AND METHODS Thirty male SD rats were randomly and equally divided into a control group, a model group, and a Cuscuta group (5.0 g/kg/d) (n=10). The rat model of unilateral cryptorchidism in the model and Cuscuta groups was established by removal of the right gubernaculum, while rats in the control group received no treatment. After modeling, rats in the Cuscuta chinensis group were intragastrically administered Cuscuta chinensis extract (5.0 g/kg/d), while rats in the control group and model group were administered an equal volume of normal saline. After 90 days, all the rats were sacrificed and the testicles were separated and weighed, followed by TUNEL staining to detect germ cell apoptosis, flow cytometry to measure JC-1, ROS, and MDA, and Western blot analysis to evaluate the expression of Bax, Bcl-2, and cleaved caspase3. RESULTS Ninety days after the operation, Cuscuta chinensis Lam significantly minimized the damage caused by modeling by increasing weight of testis, reducing the germ cell apoptosis, and enhancing the mitochondrial membrane potential of testicles, as shown by levels of JC-1, ROS, and MDA, as well as elevating the level of Bcl-2/Bax and reducing the level of cleaved caspase3 (P<0.05). CONCLUSIONS Treatment with Cuscuta chinensis Lam reduced the germ cell apoptosis in rats with unilateral cryptorchidism, which provides new insight for the development of cryptorchidism therapy in the future.

The in-capillary- 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)-sweeping micellar electrokinetic chromatography - Diode array detector method for screening and quantifying trace natural antioxidants from Schisandra chinensis

An in-capillary 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)-sweeping micellar electrokinetic chromatography-diode array detector (ABTS⁺-sweeping MEKC-DAD) method was developed and successfully applied to screening and quantifying antioxidative ingredients from natural products. The parameters affecting sweeping and separation were optimized including components of background electrolyte and sample matrix. Comparing with previously reported MEKC, the sensitivity enhancement factors of trace natural antioxidants obtained by this proposed method were from 17 to 167. The limit of detection was as low as 6 ng·mL^-1. The results of other validation parameters including linearity, reproducibility, accuracy and recovery were satisfactory. Seven compounds including schizandrin, schisandrol B, schisantherin B, schisantherin A, schisanhenol, deoxyschizandrin, schisandrin B were identified as the main antioxidants in Schisandra chinensis. It was demonstrated that this developed in-capillary ABTS⁺-sweeping MEKC-DAD is simple, sensitive, reliable and rapid method for screening and quantifying trace antioxidants from natural products.

On-line high-performance liquid chromatography coupled with biochemical detection method for screening of α-glucosidase inhibitors in green tea

An on-line high-performance liquid chromatography-biochemical detection (HPLC-BCD) method, in which compounds separated by HPLC were on-line reacted with enzyme and substrate solutions delivered by flow injection and the enzyme inhibition signal was collected by UV detection, was developed to rapidly screen α-glucosidase inhibitors from green tea extracts in this study. The chromatographic fingerprints and enzyme inhibition profiles of the different brands of green tea could be simultaneously detected by the on-line HPLC-BCD method. Enzyme inhibition profiles were detected by the UV detector at 415 nm based on the reaction of α-glucosidase and p-nitrophenyl α-d-glucopyranoside (PNPG). PNPG (1.25 mm), α-glucosidase (0.4 U/mL) and the flow rate 0.07 mL/min were applied as optimized parameters to detect α-glucosidase inhibitors in green tea. Four components in green tea showed α-glucosidase inhibition action and three of them were identified as HHDP-galloyl glucose, (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate by HPLC-fourier-transform mass spectrometry (HPLC-FTMS). Two brands of green tea derived from Mengding and Enshi mountainous areas might be superior to the other samples in the prevention and treatment of diabetes owing to their stronger activities of enzyme inhibitors. The proposed on-line HPLC-BCD method could be used to rapidly identify the potential enzyme inhibitors in complex matrixes.

A powerful on line ABTS+-CE-DAD method to screen and quantify major antioxidants for quality control of Shuxuening Injection

A novel method of on-line 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate)-Capillary Electrophoresis-Diode Array Detector (on-line ABTS⁺-CE-DAD) was developed to screen the major antioxidants from complex herbal medicines. ABTS⁺, one of well-known oxygen free radicals was firstly integrated into the capillary. For simultaneously detecting and separating ABTS⁺ and chemical components of herb medicines, some conditions were optimized. The on-line ABTS⁺-CE-DAD method has successfully been used to screen the main antioxidants from Shuxuening injection (SI), an herbal medicines injection. Under the optimum conditions, nine ingredients of SI including clitorin, rutin, isoquercitrin, Quercetin-3-O-D-glucosyl]-(1-2)-L-rhamnoside, kaempferol-3-O-rutinoside, kaempferol-7-O-β-D-glucopyranoside, apigenin-7-O-Glucoside, quercetin-3-O-[2-O-(6-O-p-hydroxyl-E-coumaroyl)-D-glucosyl]-(1-2)-L-rhamnoside, 3-O-{2-O-[6-O-(p-hydroxyl-E-coumaroyl)-glucosyl]}-(1-2) rhamnosyl kaempfero were separated and identified as the major antioxidants. There is a linear relationship between the total amount of major antioxidants and total antioxidative activity of SI with a linear correlation coefficient of 0.9456. All the Relative standard deviations of recovery, precision and stability were below 7.5%. Based on these results, these nine ingredients could be selected as combinatorial markers to evaluate quality control of SI. It was concluded that on-line ABTS⁺-CE-DAD method was a simple, reliable and powerful tool to screen and quantify active ingredients for evaluating quality of herbal medicines.

Quantitative Analysis of Phenolic Acids and Flavonoids in Cuscuta chinensis Lam. by Synchronous Ultrasonic-Assisted Extraction with Response Surface Methodology

An effective ultrasonic-assisted extraction method for the separation of phenolic acids and flavonoids in Cuscuta chinensis Lam. was conducted by combining uniform design (UD) coupled with response surface methodology (RSM) and orthogonal design (OD) experiment. A sensitive and selective high-performance liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (HPLC-ESI-MS/MS) method was applied to quantify the sixteen active ingredients (chlorogenic acid, cryptochlorogenic acid, neochlorogenic acid, isochlorogenic acid A, isochlorogenic acid B, isochlorogenic acid C, caffeic acid, hyperin, isoquercitrin, quercetin, campherol, p-coumaric acid, isorhamnetin, rutin, astragalin, and apigenin). The extraction method was optimized with respect to concentration of extraction solvent, extraction time, and ratio of liquid to solid as a consequence of getting a high sensitive and feasible method for simultaneous determination of contents of multiple components and evaluation of quality control of Cuscuta chinensis Lam. from different origins. It was also considered useful and valuable in the further study for quality control of Cuscuta chinensis Lam.