In Vitro Synthesis of Betaxanthins Using Recombinant DOPA 4,5-Dioxygenase and Evaluation of Their Radical-Scavenging Activities
详细信息 查看全文
- 作者：Hiroshi Sekiguchi ; Yoshihiro Ozeki ; Nobuhiro Sasaki
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2010
- 出版时间：December 8, 2010
- 年：2010
- 卷：58
- 期：23
- 页码：12504-12509
- 全文大小：780K
- 年卷期：v.58,no.23(December 8, 2010)
- ISSN：1520-5118
文摘
Betalamic acid, the chromophore of betaxanthins, was enzymatically synthesized on a large scale from l-dihydroxyphenylalanine (L-DOPA) using recombinant Mirabilis jalapa DOPA 4,5-dioxygenase. After synthesis, proline was directly added to the concentrated reaction mixture to generate proline-betaxanthin. The molecular mass and nuclear magnetic resonance spectrum of the purified product were identical to those previously reported for proline-betaxanthin. Twenty-four betaxanthin species were synthesized by the condensation reaction of purified betalamic acid and amino acids or amines. An HPLC protocol was established for identifying the different betaxanthin species. Proline-, dopamine-, and γ-aminobutyric acid (GABA)-betaxanthins were prepared as representative betaxanthins under large-scale conditions, and their 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activities were compared against those of known antioxidants. GABA-betaxanthin showed comparatively low activity, whereas dopamine-betaxanthin had similar activity to the red pigment betanin and the anthocyanin cyanidin 3-glucoside. Proline-betaxanthin had the highest activity of the three synthesized compounds and was similar to the flavonoid quercetin.