Weijie Zhao

Rapid discrimination and quantification of alkaloids in Corydalis Tuber by near-infrared spectroscopy.

With the application of near-infrared spectroscopy (NIRS), a convenient and rapid method for determination of alkaloids in Corydalis Tuber extract and classification for samples from different locations have been developed. Five different samples were collected according to their geographical origin, 2-Der with smoothing point of 17 was applied as the spectral pre-treatment, and the 1st to scaling range algorithm was adjusted to be optimal approach, classification model was constructed over the wavelength range of 4582-4270 cm⁻¹, 5562-4976 cm⁻¹ and 7000-7467 cm⁻¹ with a great recognition rate. For prediction model, partial least squares (PLS) algorithm was utilized referring to HPLC-UV reference method, the optimum models were obtained after adjustment. Pre-processing methods of calibration models were COE for protopine and min-max normalization for palmatine and MSC for tetrahydropalmatine, respectively. The root mean square errors of cross-validation (RMSECV) for protopine, palmatine, tetrahydropalmatine were 0.884, 1.83, 3.23 mg/g. The correlation coefficients (R²) were 99.75, 98.41 and 97.34%. T test was applied, in the model of tetrahydropalmatine; there is no significant difference between NIR prediction and HPLC reference method at 95% confidence interval with t=0.746

Rapid quantification of flavonoids in propolis and previous study for classification of propolis from different origins by using near infrared spectroscopy

A fast, simple and accurate near infrared spectroscopy (NIRs) method was investigated for the geographical origin discrimination and main flavonoid content determination of Chinese propolis. 180 propolis samples from four provinces of China were collected for establishing partial least squares (PLS) models of rutin, myricetin, quercetin, kaempferol, apigenin, izapinin, pinocembrin, chrysin, galangin and total flavonoids. The root mean square error of prediction (RMSEP) and correlation coefficient (R2) in the test set of the optimum models were 0.479 to 1.332% and 76.23 to 96.68%. The residual prediction deviation (RPD) values were all larger than 2.93. A paired t-test result showed that there was no significant difference between NIRs and HPLC methods at a 95% confidence interval. A principal component analysis (PCA)–Mahalanobis distance (MD) method was applied to classify the geographical origin of propolis samples, and 100% accuracy was obtained. Finally, a quality assessment was performed, and the propolis samples from Zhejiang and Liaoning province were classified as good quality. The developed NIRs method was a suitable tool for the rapid analysis of Chinese propolis, and might be also extended to the on-line quality control of propolis raw material in pharmaceutical industries, or monitoring industrial natural products extraction processes.

Discrimination and content analysis of fritillaria using near infrared spectroscopy.

Fritillaria is a traditional Chinese herbal medicine which can be used to moisten the lungs. The objective of this study is to develop simple, accurate, and solvent-free methods to discriminate and quantify Fritillaria herbs from seven different origins. Near infrared spectroscopy (NIRS) methods are established for the rapid discrimination of seven different Fritillaria samples and quantitative analysis of their total alkaloids. The scaling to first range method and the partial least square (PLS) method are used for the establishment of qualitative and quantitative analysis models. As a result of evaluation for the qualitative NIR model, the selectivity values between groups are always above 2, and the mistaken judgment rate of fifteen samples in prediction sets was zero. This means that the NIR model can be used to distinguish different species of Fritillaria herbs. The established quantitative NIR model can accurately predict the content of total alkaloids from Fritillaria samples.

Syntheses of new chlorin derivatives containing maleimide functional group and their photodynamic activity evaluation

Nine new chlorin derivatives containing maleimide functional group and amino acid residue with chlorin e6 scaffold (compounds 1-6) or pheophorbide a scaffold (compounds 7-9) were synthesised from chlorophyll a. The all nine derivatives demonstrated increased photo cytotoxic activity in HepG2 cell (IC50 3.2-20.5 μM) comparing with chlorin e6 and its trimethyl ester. Their photo cytotoxicities were approximately dependent on their abilities to produce singlet oxygen ((1)O2) in the cells.

Purification of bufadienolides from the skin of Bufo bufo gargarizans Cantor with positively charged C18 column.

As a kind of promising anticancer compounds, the preparation of bufadienolides is a hot study spot. However, due to the complexity of biological sample, the purification of bufadienolides from a crude sample (toad skin) is a tough work. In this paper, we reported a new way based on positively charged C18 material (XCharge C18) to quickly separate and purify bufadienolides from toad skin. By this method, the different ionic feature of the amino acid conjugated bufadienolides (AACBs) and the free form bufadienolides (AAUBs) was firstly utilized to obtain distinct separation selectivity on the XCharge C18 column. Additionally, the peak tailing problem of AACBs on conventional C18 was resolved and better resolutions were achieved on the XCharge C18, thus, two kinds of bufadienolides on one column were successfully purified respectively. Taking F13 as an example, the method was validated by liquid chromatography-mass spectrometry (LC-MS), and then 4 AACBs as well as 4 AAUBs were simultaneously purified by preparative XCharge C18. In addition, the application of this method in other fractions was also validated. The results suggested that the developed method is a practical and promising tool for efficient separation and purification of bufadienolides from toad skin.

Chemiluminescence diminishment on a paper-based analytical device: high throughput determination of β-agonists in swine hair

beta-Agonists are a group of illegal but widely used feed additives in the stockbreeding industry. In order to achieve simple-to-use, fast and high-throughput testing of this banned chemical, herein we suggest a paper-based analytical device on which a chemiluminescence diminishment method was performed. In this approach, extracts from swine hair samples as well as luminescent reagents, such as luminol and potassium periodate solution, in a low volume were applied to our device. It was found that the light emission was diminished by the beta-agonists extracted from the swine hair samples. The degree of diminishment is proportional to the concentration of the beta-agonists from 1.0 x 10(-5) to 1.0 x 10(-8) mol L-1. Also, the concentrations of solutions for chemiluminescence were optimized. The mechanism and reaction kinetics of chemiluminescence were discussed as well. The detection limit was obtained as 1.0 x 10(-9) mol L-1, and recoveries from 96% to 110% were achieved, both of which suggested that our method will be favourable in field applications for swine hair samples.

Efficient purification of low molecular weight nitrogen polar compounds from the skin of Bufo bufo gargarizans Cantor by reversed-phase high performance liquid chromatography with a polar-copolymerized C18 stationary phase

Cinobufacini (Huachansu) injections have been widely used for the treatment of various cancers in clinical applications in China. As an aqueous extract of the skin of Bufo bufo gargarizans Cantor (toad skin), cinobufacini contains many polar compounds; however the chemical profile of these polar compounds is still unclear, which increases the risk of pharmacological safety. There are very few studies on the separation and purification of polar components from toad skin, especially in the preparative scale. In this study, a unique method based on a homemade polar-modified C18 stationary phase was developed and successfully applied to separate polar compounds from toad skin. Compared with previous purification systems based on the C18 stationary phase, the poor retention problem of polar compounds was well resolved through the use of the polar-modified C18 column and good resolutions were also achieved. Seven compounds were purified and five of them (uracil, hypoxanthine, 3-hydroxy-4H-pyrazolo[4,5-d]pyridazin-7(1H)-one, thymine and bufothionine) were identified by MS, 1H NMR and 13C NMR. In addition, 3-hydroxy-4H-pyrazolo[4,5-d]pyridazin-7(1H)-one was identified as a new compound and hypoxanthine was found from the skin of Bufo bufo gargarizans Cantor for the first time. These results indicate that this method shows promise for the separation of polar compounds in toad skin.

Easy-to-fabricate thin-film coating on PDMS substrate with super hydrophilicity and stability

With the fast expansion of microfluidic applications, stable, and easy‐to‐fabricate PDMS surface coating with super hydrophilicity is highly desirable. In this study, we introduce a new kind of copolymer‐based, single‐layer thin‐film coating for PDMS. The coating can exist in air at room temperature for at least 6 months without any noticeable deterioration in the super hydrophilicity (water contact angle ∼7°), resistance of protein adsorption, or inhibition of the EOF. In addition, this coating enables arbitrary patterning of cells on planar surfaces.

Direct measurement of beta‐agonists in swine hair extract in multiplexed mode by surface‐enhanced Raman spectroscopy and microfluidic paper

Bare gold nanoparticles selectively enhance the Raman signal of beta‐agnonists in swine hair extract at 780 nm, which enables analysis of beta‐agonists in swine hair extract without chemical labeling, purification, or separation. The analysis is multiplexable and the LOD of beta‐agonists is around ng/mL in the assistance of microfluidic paper.

Screening and identification of natural ligands of tyrosinase from Pueraria lobata Ohwi by a combination of ultrafiltration and LC-MS

Ultrafiltration combined with liquid chromatography-mass spectrometry (UF-LC-MS) is an efficient affinity-based method to screen potential ligands of biomacromolecules from natural sources. In order to investigate the effects of constituents from Pueraria labta Ohwi on tyrosinase, a UF-LC-MS method for screening tyrosinase ligands was established. Seven constituents were screened as tyrosinase ligands with high affinity and their structures were elucidated as isoflavones and isoflavone glycosides by mass spectrum analysis, among which puerarin exhibited much stronger inhibitory activity in vitro than arbutin against tyrosinase. An in silico docking study indicates that the interaction between puerarin and tyrosinase mainly derived from hydrogen bonds and π–cation interaction.