Wu Jiumn-Yih, Ding Hsiou-Yu, Wang Tzi-Yuan, Tsai Yu-Li, Ting Huei-Ju, Chang Te-Sheng
Department of Food Science, National Quemoy University, Kinmen County 892, Taiwan.
Department of Cosmetic Science, Chia Nan University of Pharmacy and Science, No. 60 Erh-Jen Rd., Sec. 1, Jen-Te District, Tainan 71710, Taiwan.
Antioxidants (Basel). 2021 Nov 16;10(11):1817. doi: 10.3390/antiox10111817.
Mangiferin is a natural antioxidant -glucosidic xanthone originally isolated from the (mango) plant. Mangiferin exhibits a wide range of pharmaceutical activities. However, mangiferin's poor solubility limits its applications. To resolve this limitation of mangiferin, enzymatic glycosylation of mangiferin to produce more soluble mangiferin glucosides was evaluated. Herein, the recombinant maltogenic amylase (MA; E.C. 3.2.1.133) from a thermophile DSM 18751 (MA) was cloned into BL21 (DE3) via the expression plasmid pET-Duet-1. The recombinant MA was purified via Ni affinity chromatography. To evaluate its transglycosylation activity, 17 molecules, including mangiferin (as sugar acceptors), belonging to triterpenoids, saponins, flavonoids, and polyphenol glycosides, were assayed with β-CD (as the sugar donor). The results showed that puerarin and mangiferin are suitable sugar acceptors in the transglycosylation reaction. The glycosylation products from mangiferin by MA were isolated using preparative high-performance liquid chromatography. Their chemical structures were glucosyl--(1→6)-mangiferin and maltosyl--(1→6)-mangiferin, determined by mass and nucleic magnetic resonance spectral analysis. The newly identified maltosyl--(1→6)-mangiferin showed 5500-fold higher aqueous solubility than that of mangiferin, and both mangiferin glucosides exhibited similar 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activities compared to mangiferin. MA is the first MA with glycosylation activity toward mangiferin, meaning mangiferin glucosides have potential future applications.
芒果苷是一种天然抗氧化剂——葡糖苷黄酮，最初从芒果植物中分离得到。芒果苷具有广泛的药理活性。然而，芒果苷的低溶解度限制了其应用。为了解决芒果苷的这一局限性，对芒果苷进行酶促糖基化以生产更易溶的芒果苷葡糖苷进行了评估。在此，将来自嗜热栖热放线菌DSM 18751的重组麦芽糖生成淀粉酶（MA；E.C. 3.2.1.133）通过表达质粒pET-Duet-1克隆到大肠杆菌BL21（DE3）中。重组MA通过镍亲和色谱法纯化。为了评估其转糖基化活性，以β-环糊精（作为糖供体）对包括芒果苷（作为糖受体）在内的17种属于三萜类、皂苷类、黄酮类和多酚苷类的分子进行了测定。结果表明，葛根素和芒果苷是转糖基化反应中合适的糖受体。通过制备型高效液相色谱法分离了MA作用于芒果苷的糖基化产物。通过质谱和核磁共振光谱分析确定其化学结构为葡糖基-α-(1→6)-芒果苷和麦芽基-α-(1→6)-芒果苷。新鉴定的麦芽基-α-(1→6)-芒果苷的水溶性比芒果苷高5500倍，并且与芒果苷相比，两种芒果苷葡糖苷表现出相似的1,1-二苯基-2-苦基肼自由基清除活性。MA是首个对芒果苷具有糖基化活性的麦芽糖生成淀粉酶，这意味着芒果苷葡糖苷具有潜在的未来应用前景。
