DunaIiella salina, a halotolerent unicellular green alga, can accurmulate a Iarge amount of β-caroteneunder environmental conditions. The isorners of β-carotene extIacted from D. salina culturedin medium with differ...DunaIiella salina, a halotolerent unicellular green alga, can accurmulate a Iarge amount of β-caroteneunder environmental conditions. The isorners of β-carotene extIacted from D. salina culturedin medium with different nitrate and phosphate concentrations were analysed by HPLC with Alox-Talumins column. At least six isomers were found in different proportions depending on the culture me-dia’s nitrate and/or phosphate concentrations. Nitrate and/or phosphae defidency was conducive tothe accumulation of totaI cis isomers but not of al1 trans isomer. lt is sUggeSted that 1 mmol/L KNO<sub>3</sub>and 0.1 mmol/L KH<sub>2</sub>, PO<sub>4</sub> are favourable for accumulation of total cis β-carotene.展开更多
A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiol...A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiolane lactol 5 by SOCl2/DMF, followed by coupling with silylated N^4- acetylcytosine and deprotection. The overall yield was 42.6 % and 20,1%, respectively.展开更多
All-trans spheroidene was extracted from the cells of Rhodobacer sphaeroides 2.4.1 and a set of cis-trans isomers were isolated from an isomeric mixture obtained by iodine-sensitized photo-isomerization of the all-tra...All-trans spheroidene was extracted from the cells of Rhodobacer sphaeroides 2.4.1 and a set of cis-trans isomers were isolated from an isomeric mixture obtained by iodine-sensitized photo-isomerization of the all-trans isomer by high-pressure liquid chromatography (HPLC). On the basis of assignment of the 1H-NMR spectra (COSY, long-range COSY, rekyed COSY, ROESY and NOESY) of the all-trans isomer, the configurations of cis isomers were determined by the isomerization shifts of the olefinic 1H signals. The peaks of HPLC could be assigned as follows: A: 9,13’-cis, B1: 5,13-cis, B2: 13,9’-cis, C: 13-cis, E: 9-cis, F: 13’-cis, G: 5,9’-cis, H: 9’-cis, I: all-trans.展开更多
基金This project was supported by the National Natural Science Foundation of China,Grant No.38970587.
文摘DunaIiella salina, a halotolerent unicellular green alga, can accurmulate a Iarge amount of β-caroteneunder environmental conditions. The isorners of β-carotene extIacted from D. salina culturedin medium with different nitrate and phosphate concentrations were analysed by HPLC with Alox-Talumins column. At least six isomers were found in different proportions depending on the culture me-dia’s nitrate and/or phosphate concentrations. Nitrate and/or phosphae defidency was conducive tothe accumulation of totaI cis isomers but not of al1 trans isomer. lt is sUggeSted that 1 mmol/L KNO<sub>3</sub>and 0.1 mmol/L KH<sub>2</sub>, PO<sub>4</sub> are favourable for accumulation of total cis β-carotene.
文摘A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiolane lactol 5 by SOCl2/DMF, followed by coupling with silylated N^4- acetylcytosine and deprotection. The overall yield was 42.6 % and 20,1%, respectively.
文摘All-trans spheroidene was extracted from the cells of Rhodobacer sphaeroides 2.4.1 and a set of cis-trans isomers were isolated from an isomeric mixture obtained by iodine-sensitized photo-isomerization of the all-trans isomer by high-pressure liquid chromatography (HPLC). On the basis of assignment of the 1H-NMR spectra (COSY, long-range COSY, rekyed COSY, ROESY and NOESY) of the all-trans isomer, the configurations of cis isomers were determined by the isomerization shifts of the olefinic 1H signals. The peaks of HPLC could be assigned as follows: A: 9,13’-cis, B1: 5,13-cis, B2: 13,9’-cis, C: 13-cis, E: 9-cis, F: 13’-cis, G: 5,9’-cis, H: 9’-cis, I: all-trans.
