Spectroscopy and molecular docking analysis reveal structural specificity of flavonoids in the inhibition of α-glucosidase activity.

The inhibition of α-glucosidase activity is a prospective approach to prevent postprandial hyperglycemia. As two flavonoids extracted from citrus fruits, eriocitrin and eriodictyol have similar structures and show multiple pharmacological activities. In order to investigate the effects of flavonoids structure on enzyme inhibition, spectroscopy and molecular docking analysis were used. Saccharomyces cerevisiae α-glucosidase (GH13) was used for studying the inhibitory mechanism by multi-spectroscopic analysis. Results indicated that they could quench the intrinsic fluorescence of α-glucosidase, the binding constants at 298 K were (7.02 ± 0.22) × 104 and (4.57 ± 0.16) × 104 L mol-1, respectively. The interaction between them with α-glucosidase were mainly driven by hydrophobic interaction, they induced conformational changes of α-glucosidase. The human α-glucosidase (C-terminal maltase-glucoamylase, GH31) was used in the molecular docking analysis to determine the interaction of eriocitrin and eriodictyol with the α-glucosidase. The results revealed that they could bind with α-glucosidase and might cause the decrease of α-glucosidase activity. The inhibitory effect of eriocitrin was stronger than that of eriodictyol, which might be due to the position and amount of hydroxyl groups. This work confirmed two novel α-glucosidase inhibitors and provided the structure-function relationship of flavonoids in inhibition of α-glucosidase activity.

[Fingerprinting of Panax notoginseng by high-performance liquid chromatography].

Fingerprinting of Panax notoginseng was performed by high-performance liquid chromatography using Agilent Hypersil C18 (250.0 mm x 4.0 mm, 5 microm) column with the mobile phase of acetonitrile and water and gradient elution. The detection wavelength was set at 203 nm. The method is simple and reliable to identify and evaluate the quality of Panax notoginseng.

[Content determination of S-citalopram by chiral high-performance liquid chromatography].

OBJECTIVE: To separate the enantiomers of citalopram and determine the content of S-citalopram using chiral high-performance liquid chromatography (HPLC). METHODS: The chiral column CHIROBIOTIC V was used with the mobile phase using methanol-acetic acid-triethylamine (100:0.1:0.1) at the detection wavelength of 240 nm, column temperature of 20 degrees Celsius and flow rate of 1.0 ml/min. RESULTS: Complete separation of the enantiomers of citalopram was achieved, and S-citalopram exhibited good linearity within the concentration range of 10 to 150 microg/ml (r=0.9991, n=5). CONCLUSION: This method allows accurate quantification of S- and R-citalopram and is well suited for drug interaction investigations.

One-pot synthesis of novel isoindoline-1,3-dione derivatives bearing 1,2,4-triazole moiety and their preliminary biological evaluation.

A series of novel isoindoline-1,3-diones containing 1,2,4-triazole moiety were synthesized via a one-pot reaction. Bioassay indicated that compounds 33, 35, 37 and 39 exhibited much higher activities against Botryodiplodia theobromae than commercial fungicide triadimefon at the dosage of 150 mg/L. Most interestingly, compounds 36, 37 and 45 displayed much stronger antitumor activities against four human cell lines than positive control Fluorouracil. Particularly, compound 37 had four-fold improvement compared to Fluorouracil in inhibiting A549 and HepG2 cell proliferation with IC(50) values of 6.76 and 9.44 µM, respectively. Further flow-activated cell sorting analysis revealed that compound 37 displayed apoptosis-inducing effect on HepG2 cells in a dose-dependent manner. These encouraging results could be helpful for the development of new antitumor compounds.

[Determination of organochlorine pesticide residue in nine Chinese herbs by gas chromatography].

OBJECTIVE: To determine organochlorine pesticide residue in 9 Chinese herbs. METHODS: The organochlorine pesticides were extracted from the herbs with mixed solvents of n-hexane and acetone by a solid-phase extraction cartridge Florisil. Capillary gas chromatography was used to separate the samples. RESULTS: Good linearities were obtained for 11 organochlorine pesticides. The average recoveries at two concentration levels ranged from 79.9% to 89.0%,and from 86.3% to 104.8%, with relative standard deviations of 1.8% to 7.1%, respectively and detection limit of 2 g/kg. The residues of the organic pesticides exceeded national standard in Pogostemon cablin and Panax notoginseng. CONCLUSION: Capillary gas chromatography combined with electron capture detection provides a practical means for detecting organic pesticide residue in Chinese herbal medicines, and the limits of pesticide residues should be formulated in Chinese pharmacopoeia.