Catechins in green tea are well‐known to be effective in reducing the risk of obesity. The purpose of this study was to elucidate the effects of catechins present in green tea on adipocyte differentiation and mature adipocyte metabolism. Treatment of 3T3‐L1 mouse adipocyte during differentiation adipocytes with (−)‐epigallocatechin (EGC) and gallic acid (GA) resulted in dose‐dependent inhibition of adipogenesis. Specifically, EGC increased adiponectin and uncoupling protein 1 (UCP1) transcription in mature adipocytes. Transcription levels of adipose triglyceride lipase (ATGL) and hormone‐sensitive lipase (HSL) were not significantly impacted by either of the compounds. These results suggest that the EGC is the most effective catechin having anti‐obesity activity. Finally, EGC is an attractive candidate component for remodeling obesity.
Rebaudioside A was modified via glucosylation by recombinant dextransucrase of Leuconostoc lactis EG001 in Escherichia coli BL21 (DE3), forming single O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A with yield of 86%. O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A was purified using HPLC and Diaion HP‐20 and its properties were characterized for possible use as a food ingredient. Almost 98% of O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A was dissolved after 15 days of storage at room temperature, compared to only 11% for rebaudioside A. Compared to rebaudioside A, O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A showed similar or improved acidic or thermal stability in commercial drinks. Thus, O‐α‐D‐glucosyl‐(1″→6′) rebaudioside A could be used as a highly pure and improved sweetener with high stability in commercial drinks.
Practical Application
The proposed method can be used to generate glucosyl rebaudioside A by enzymatic glucosylation. Simple glucosyl rebaudioside A exhibited high acid/thermal stability and improved sweetener in commercialized drinks. This method can be applied to obtain high value‐added bioactive compounds by enzymatic modification.
Cycloisomaltooligosaccharide glucanotransferase (CITase) was isolated from alkaliphilic Paenibacillus daejeonensis via an amino acid homology search for the reported CITase. The recombinant alkaliphilic CITase (PDCITase) from P. daejeonensis was expressed in an Escherichia coli expression system and purified as a single protein band of 111 kDa. PDCITase showed optimum activity at pH 8.0 and retained 100% of activity within a broad pH range (7.0-11.5) after 18 h, indicating alkaliphilic or alkalistable CITase properties. In addition, PDCITase produced CI-7 to CI-17, CI-18, and CI-19, which are relatively large cycloisomaltooligosaccharides yet to be reported. Therefore, these large cycloisomaltooligosaccharides can be applied to the improvement of water solubility of pharmaceutical biomaterials.
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