FOOD CHEMISTRY
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2013
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IF 3.334
Guobin Xia,Shan Hong,Songbai Liu
Simultaneous preparation of naturally rare catechins , EGC and EC , has been realized by tannase-mediated biotransformation combining high speed counter current chromatography. In addition, simultaneous preparation of the four catechins, EGCG, ECG, EGC, and EC in green tea extract has also been achieved by HSCCC under the normal phase and the reversed phase modes. The identity of the catechins was determined by HPLC-DAD-ESI-MS and quantification of the catechins was performed by HPLC-DAD. In a typical HSCCC separation, 27.2 mg 98.8% EGCG, 14.1 mg 94.7% EGC, and 9.3 mg 97.5% EC were obtained. This new method is efficient, time-saving and valuable for biological studies.
研究领域:
植物化学
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生物技术
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分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICO-BIOLOGICAL INTERACTIONS
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2023
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IF 5.1
Xiaoting Luo,Feifei Lu,Zhiyue Yin,Zhiyun Zhou,Zhongmin Wang,Hongjian Zhang
Carboxylesterase 1 (CES1) is a hydrolytic enzyme that plays an important role in the activation or deactivation of many therapeutic agents, thus affecting their pharmacokinetic and pharmacodynamic outcomes. Using rat liver S9 as an enzyme source and enalapril as a CES1 substrate, the present study examined effects of a number of flavonoids on the formation of enalaprilat (the active form of enalapril) produced by CES1-mediated hydrolysis. While a majority of flavonoids tested showed inhibition on CES1, an unexpected hormetic effect was observed for epigallocatechin (EGC) and epigallocatechin gallate (EGCG), i.e., stimulatory effect at low concentrations and enzyme inhibition at high concentrations. Further experiments revealed that oxidative stress caused by hydrogen peroxide, arachidonic acid plus iron, and oxidized low density lipoproteins (oxLOL) reduced CES1 activity in rat liver S9 and the loss of CES1 enzyme activity could be rescued largely by EGC or EGCG. In contrast, such effects were minimal in human liver S9, probably due to the presence of a higher ratio of reduced vs oxidized forms of glutathione . The above findings suggest that the polyphenolic nature of EGC or EGCG might be responsible for rescuing CES1 activity under oxidative stress. Because of the importance of CES1 in drug activation or deactivation and rat liver S9 as a versatile in vitro system used for drug metabolism studies and drug safety assessment , caution should be exercised to avoid potential biases for data interpretation and decision making when CES1 activity in rat liver S9 is evaluated with dependency on experimental conditions.
研究领域:
药理学
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毒理学
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生物化学
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药物代谢
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酶学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
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2024
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IF 4
Xiaoyan Shen,Xiaofen Wu,Hui Qi,Dongning Wei,Ming Deng,Keqin Wang,An Liu,Liang Chen
This study focused on the efficiency of enzymatic synthesis for theaflavins (TFs) and SII types of thearubigins (SII-TRs) in suspended fermentation of different varieties of tea leaves. The results showed that the content of catechins in tea variety-Xiaoxianghong 21-3 (XXH21-3) was the highest among the five kinds of fresh tea leaves, and it had the strongest ability of transforming catechins to TFs and SII-TRs. The total amount of catechins for XXH 21-3 decreased rapidly and the conversion ratio of TFs reached the highest level of 13.96% after 20 min, the residual catechins was the lowest (3.08%) and the conversion rate of SII-TRs was the highest (13.02%) after 120 min during the suspended fermentation of five varieties tea leaves. Among the six catechin types, epicatechin gallate (ECG), epigallocatechin gallate (EGCG) and epigallocatechin (EGC) were consumed in large quantities, and the residues were all less than 5% in the final stage of fermentation, of which ECG consumption was the fastest, followed by EGCG. These results demonstrated that the concentration of catechins and PPO activities were positively correlated with the formation of TFs and SII-TRs, POD activity was positive correlation with synthesis of SII-TRs and negative correlation with TFs.
研究领域:
食品科学
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茶叶化学
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酶学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2024
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IF 13.3
Zhipeng Ni,Haiying Zhou,Haojie Yu,Li Wang,Chenguang Ouyang,Jian Yang,Yanzhao Dong,Ahmad Alhaskawi,Tian Tu,Hui Lu
The bidirectional regulations of antiadhesion and regeneration are crucial for Achilles tendon injuries. However, the precise prevention and treatments of peritendinous adhesions both in time and space are still great challenges. Here, a series of time–space regulating prodrug (tannic acid (TA), epigallocatechin (EGC) and epigallocatechin gallate (EGCG)) hydrogels are designed for the prevention of peritendinous adhesion in Achilles tendon contusion and rupture injuries. In the term of space, the self-healing and deformable hydrogels prepared by crosslinking phenylboric acid (PBA) functionalized polyphosphazene (PZBA) with guar gum (GG) through ROS-responsive phenylborate ester (PBAE) can specifically aggregate to the high ROS sites via the ROS-responsive degradation and recombination of PBAE. Thus, providing support and acting as barriers to inhibit fibroblast proliferation. In the term of time, the prodrug strategy using ROS-responsive PBAE as bridging linker can achieve long-term anti-inflammatory effect over 2 weeks. Furthermore, the degradation time of hydrogels matched the course of peritendinous adhesion, thus achieved bidirectional regulations (decrease the gene expression of TGF-β1, COL-1 and COL-3 to antiadhesion in the early stage but increase them to promote regeneration in the late stage). This study presents a promising approach employing smart prodrug hydrogels with time–space regulating properties for prevention of peritendinous adhesion.
研究领域:
生物医学工程
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药剂学
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材料科学
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组织工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）