Improving Aqueous Solubility of Natural Antioxidant Mangiferin through Glycosylation by Maltogenic Amylase from Parageobacillus galactosidasius DSM 18751

Mangiferin is a natural antioxidant C-glucosidic xanthone originally isolated from the Mangifera indica (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 Parageobacillus galactosidasius DSM 18751T (PgMA) was cloned into Escherichia coli BL21 (DE3) via the expression plasmid pET-Duet-1. The recombinant PgMA was purified via Ni2+ 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 PgMA were isolated using preparative high-performance liquid chromatography. Their chemical structures were glucosyl-α-(1→6)-mangiferin and maltosyl-α-(1→6)-mangiferin, determined by mass and nucleic magnetic resonance spectral analysis. The newly identified maltosyl-α-(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. PgMA is the first MA with glycosylation activity toward mangiferin, meaning mangiferin glucosides have potential future applications.

Fresh bread to the last piece

The use of technological solutions based on enzyme preparations of maltogenic amylase of the Novamyl® Boost series and Novamyl® 3D BG by Novozymes company allows to prolong the freshness and softness of high-prescription products.

The structures of the GH13_36 amylases from Eubacterium rectale and Ruminococcus bromii reveal subsite architectures that favor maltose production

Bacteria in the human gut including Ruminococcus bromii and Eubacterium rectale encode starch-active enzymes that dictate how these bacteria interact with starch to initiate a metabolic cascade that leads to increased butyrate. Here, we determined the structures of two predicted secreted glycoside hydrolase 13 subfamily 36 (GH13_36) enzymes: ErAmy13B complexed with maltotetraose from E. rectale and RbAmy5 from R. bromii. The structures show a limited binding pocket extending from –2 through +2 subsites with limited possibilities for substrate interaction beyond this, which contributes to the propensity for members of this family to produce maltose as their main product. The enzyme structures reveal subtle differences in the +1/+2 subsites that may restrict the recognition of larger starch polymers by ErAmy13B. Our bioinformatic analysis of the biochemically characterized members of the GH13_36 subfamily, which includes the cell-surface GH13 SusG from Bacteroides thetaiotaomicron, suggests that these maltogenic amylases (EC 3.2.1.133) are usually localized to the outside of the cell, display a range of substrate preferences, and most likely contribute to maltose liberation at the cell surface during growth on starch. A broader comparison between GH13_36 and other maltogenic amylase subfamilies explain how the activity profiles of these enzymes are influenced by their structures.