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【期刊论文】Reversal of Cancer Multidrug Resistance by Tea Polyphenol in KB Cells
魏东芝, Y. MEI
Journal of hemotherapy Vol. 15,-0001,():
-1年11月30日
Tea polyphenols, (-)-epigallocatechin galate in pariticular, were examined for their modulating effects on the drung resistance KB-A-1 cells and drug ensitive KB-3-1 cells. Both KB3-1 and KB-A-1 cells were queally sensitive to tea polyphoenol and (-)-epigallocatechin gallate. When 10μg/ml (-)-epigalllocatechin gallate or 40μg/ml tea polyphenol were persent simultaneously iwth doxorubicin, the IC50 of doxorubicin on KB-A-1 cells decreased form 10.3±0.9μg/ml to 4.2±0.2 or 2.0±0.1μg/ml. Tea polyphenol and (-)-epigalloctechin gallate enhancedthe cytotoxicity of doxorubicin on KB-A-1 cells by 5.2 and 2.5 times, respectively, but did not show a mdulating effct on KB-3-1 cells. Both tea polyphenol and (-)-epigallocatechin gallate showed reversal effects on the multidrug resistance phenotype.
Multidrug resistance,, doxroubicin,, tea polyphenol,, (, -), -eigalloctechia gallate,, modulation
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魏东芝, Wu Su, † Zhiyuan Chang, † Keliang Gao and Dongzhi Wei*
Tetrabedron: Asmmetry 15(2004)1275-1277,-0001,():
-1年11月30日
Ghiconobacter oxydans DSM 2003 was firstly used in the production of (R)-2-hydroxy-proionic acid through microbial oxidation of recemic 1,2-propanediol. The biotransformation was processed with high enantionmeric excess (>99%) and near theoretical lyicld (48% of racemic 1,2-propanediol) when the substrate concentration was lower than 20g/L. When the substrate concentration was increased. maintaining the pH at 6.0 helped to improve the enantionselectivity.
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【期刊论文】Enzymatic Synthesis of Ethyl-glucoside Mondooleate with Lipase in Solvent-free Medium
魏东芝, DONGZHI WEI*, YING YU, QINGXUN SONG AND WU SU
Biocatalysis and Biotrnsformation, 2003, Vol. 23 (3). Pp. 135-139,-0001,():
-1年11月30日
Ethylglucoside monooleate was synthesized by esteriication between ethylglucoside and oleic acid with immobilized lipase from Candida antarctica in a solvent-free system. It was shouwn that a stirred tnk reactor was suitable for the enzymatic reaction process involving substrates with low miscibiligy, in which the biocatalyst was recycled five times without signiicant activity loss. Removal of the co-product, water, from thereactin medium by carrying out the reaction under reduced pressure benefited the esterification reaction and increased the monooleate yield up to 97% within 8 hours.
Enzymatic synthesis, Ethylglucoside morooleate, Solvent-free medium, Lipase, Esterification, Reduced pressure
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【期刊论文】Effect of temperature on the enzymatic synthesis of cefaclor with in situ product removal
魏东芝, Dongzhai Wei*, Liu Yang, Qingxun Song
Journal of Molecular Catalysis B: Enzymatic 26(2003)99-104,-0001,():
-1年11月30日
An integrated process of cefaclor synthesis from phenylglycine methyl ester (PGME) and 7-aminodesacetoxymethyl-3-chlorocephalosporanic acid (7-ACCA) catalyzd by penicilin G acylase (PGA) with in situ product removal (ISRP) was estbilshd. The ntegrted process was more significantly influenced by temperature than the separate synthesis process as without ISPR. The difference between the overall yields with and without ISPR was minfied as reaction temperanres rose. For instance, the maximum 7-ACCA comversions was 86 and 68%, respectively, in the process with and without ISPR at 5℃. Both the maximum conversions. however, decreased to around 45% at 40℃. The effect of substrate concentration on the overall converion was also obviously dependent on the reaction temperiature. Te product cefaclor inhibited PGME hydroplysis in the enzymatic syathesis. ISPR stimulated cefacor synthesis at lower temperatures, but was not useful at hight temperatures which accelerated PGME hydrolysis.
Cefactor, Enzymatic systhesis, Tempermatre, In situ product removal
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【期刊论文】Enzymatic estrification for glycoside lactate synthesis in organic solvent
魏东芝, Dongzhi Wei*, Chunang Gu, Qingxun Song, Wu Su
Eazyme and Microbial Tochaology 33(2003)508-512,-0001,():
-1年11月30日
Propyl-glycoside lacter, a new α-hydroxy acids derivative, was synthesized byesterification between lactic acid and propl-glycoside, instead oftransesteritication as reported previously, in a non-aqeous medium using immobilxed lipase as biocatalyst. A con ersion of 66% was achieved by the optimixation o the reaction conditions. Lipase activitywas found to be reduced when exposed to high conccentration mechanism of the enzymtic esterfication reaction. Additon of molecular sieves eliminated hydrolysis of the produced ester and allowed glycoside conversion rising to 75%
Propyl-glycoside lactate, Lactic acid, Propyl-glycoside, Lipae, Eazmatic synthesis
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