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Fan Ouyang

Publications and source records attributed to Fan Ouyang.

21 records · Page 2Linked to original sources

[Purification and fingerprinting development of Salvia miltiorrhiza Bunge by high-speed counter-current chromatography].

In an attempt to apply high-speed counter-current chromatography HSCCC for TCM fingerprints, the separation and purification of the Chinese medicinal plant Salvia miltiorrhiza Bunge of different localities was realized using the technique. The equipments used include a HSCCC (TBE-300) of Shenzhen Tauto Biotech containing three connected preparative coils (diameter of tube = 2.6mm, total volume = 300mL) and a 20mL sample loop and a HPLC from Shimadzu of Japan with a Ultrasphere C18 column (150 x 4.6mm ID, 5microm) and a 20microL sample loop. Salvia miltiorrhiza Bunge samples from 3 locations were separated by HSCCC in a Step-wise elution program with solvent systems A (hexane:ethanol: water = 10:5.5:4.5) and B (hexane:ethanol: water = 10:7:3) at a speed of 900 r/min and a flow-rate of 2mL/min. All the 12 peak fractions were eluted within 13 hours. The contents of each component varied greatly in different samples, which confirmed previous observation that the locations and climates have a great impact on the TCM quality and also indicated a quality control system is necessary to safeguard the quality of the herb. The retention times of the 12 peak fractions from crude extracts of the samples were collected by HPLC and the absorption spectrums of the corresponding peaks were identified. The 12 components of the three crude samples were readily distinguishable and can be used as fingerprints of S. miltiorrhiza Bunge. The relative standard deviation of the HSCCC retention times was less than 3%, which satisfies the requirement of the national standard reference index. The components 7, 8 and 11 from the standards were identified to be crypototanshinone, tanshinone I and tanshinone II A respectively. This study demonstrates that if it is possible to apply HSCCC for TCM fingerprinting, especially with samples of high viscosity and highly absorptive components. The precision and the run time of fingerprinting can be further improved if larger volume and a temperature control system is used. With these and other improvements, HSCCC is expected to play an important role in TCM development.

Abietanes↗

Effect of Amorphophallus Konjac oligosaccharides on STZ-induced diabetes model of isolated islets.

Three oligosaccharide fractions from the root of Amorphophallus Konjac, which was reported with hypoglycemic effects on diabetes subjects, were isolated and studied using the STZ-treated diabetes model. Among them, one fraction named as KOS-A, was found with nitric oxide (NO(*)) free radical regulation effect, while the other two were not. At concentrations less than 1.5 mM, KOS-A positively decreased STZ-induced NO(*) level of islets, but normal NO(*) release for non-STZ-treated islets was not affected within the range. At 15 mM, KOS-A played a contrary role and increased NO(*) level for islets both with and without STZ-treatment. Islets insulin secretion changed corresponding to NO(*) level in the assay. Increased insulin secretion appeared parallel to the decrease of NO(*), and normal insulin release was not affected by KOS-A less than 1.5 mM. Structure determination of KOS-A shows that it is a tetrasaccharide with Mw of 666 Da and reductive end of alpha-D-mannose. These results indicate that low dosage of KOS-A, with its function on attenuating STZ-induced NO(*) level, doesn't alter normal NO(*) and insulin secretion pathways of isolated islets. The NO(*) attenuation function of KOS-A on the diabetes model is mainly resulted from environmental free radical scavenging by the oligosaccharide. Present results also imply the mechanism of clinical Amorphophallus Konjac hypoglycemic function maybe related with free radical attenuation and lower risks of islets damage from NO(*) radical.

Amorphophallus↗

Optimization of a cultural medium for bacteriocin production by Lactococcus lactis using response surface methodology.

The medium composition for bacteriocin production by Lactococcus lactis ATCC 11454 was optimized using response surface methodology. The selected six factors based on CM medium were sucrose, soybean peptone, yeast extract, KH(2)PO(4), NaCl, and MgSO(4).7H(2)O. Fractional factorial designs (FFD) and the path of steepest ascent were effective in searching for the main factors and approaching the optimum region of the response. By a 2(6-2) FFD, sucrose, soybean peptone, yeast extract, KH(2)PO(4) were found to be significant factors and had positive effects on cell growth, however, only soybean peptone and KH(2)PO(4) were shown to be the two significant factors for bacteriocin production and had negative and positive effects, respectively. The effects of the two main factors on bacteriocin production were further investigated by a central composite design and the optimum composition was found to be 1% sucrose, 0.45% soybean peptone, 1% yeast extract, 2.84% KH(2)PO(4), 0.2% NaCl, and 0.02% MgSO(4) x 7H(2)O. The optimal medium allowed bacteriocin yield to be doubled compared to CM medium.

Bacteriocins↗