**4. Conclusions**

The recombinant *Pg*MA from *P. galactosidasius* DSM 18751<sup>T</sup> was confirmed to exhibit the bifunctions of hydrolysis and transglycosylation activities. The recombinant *Pg*MA can glycosylate mangiferin and produce glucosyl-*α*-(1→6)-mangiferin and maltosyl-*α*- (1→6)-mangiferin with a high maltodextrin concentration. The novel maltosyl-*α*-(1→6) mangiferin showed much higher aqueous solubility than that of mangiferin. The two mangiferin glucosides exhibited similar DPPH antioxidative activity compared to mangiferin. To our knowledge, *Pg*MA is the first MA identified with glycosylation activity toward mangiferin. With higher water solubility and compatible antioxidant activity, the two mangiferin glucoside derivatives have better pharmaceutical applicability.

**Supplementary Materials:** The following materials are available online at https://www.mdpi.com/ article/10.3390/antiox10111817/s1. Table S1: Top five candidates with best-hit of *Bs*MA from NCBI GenBank. Table S2. The list of the tested molecules in the transglycosylation reaction of *Pg*MA. Table S3: 1H and 13C NMR assignments in DMSO-*d6* at 700 and 175 MHz for compounds (**1**) and (**2**). Figure S1: Mass–mass analysis of glucosyl-*α*-(1→6)-mangiferin (**1**) in the negative mode. Figure S2: Mass–mass analysis of maltosyl-*α*-(1→6)-mangiferin (**2**) in the negative mode. Figure S3: Onedimensional NMR spectrum (1H-NMR, 700 MHz, DMSO-*d6*) of the glucosyl-*α*-(1→6)-mangiferin (**1**). Figure S4: One-dimensional NMR spectrum (13C-NMR, 175 MHz, DMSO- *d6*) of the glucosyl-*α*- (1→6)-mangiferin (**1**). Figure S5: One-dimensional NMR spectrum (DEPT-135, 175 MHz, DMSO-*d6*) of the glucosyl-*α*-(1→6)-mangiferin (**1**). Figure S6: Two-dimensional NMR spectrum (1H-13C HSQC, 700 MHz, DMSO-*d6*) of the glucosyl-*α*-(1→6)-mangiferin (**1**). Figure S7: Two-dimensional NMR spectrum (1H-13C HMBC, 700 MHz, DMSO-*d6*) of the glucosyl-*α*-(1→6)-mangiferin (**1**). Figure S8: Two-dimensional NMR spectrum (1H-1H COSY, 700 MHz, DMSO-*d6*) of the glucosyl-*α*-(1→6) mangiferin (**1**). Figure S9: Two-dimensional NMR spectrum (1H-1H NOESY, 700 MHz, DMSO-*d6*) of the glucosyl-*α*-(1→6)-mangiferin (**1**). Figure S10: One-dimensional NMR spectrum (1H-NMR, 700 MHz, DMSO-*d6*) of the maltosyl-*α*-(1→6)-mangiferin (**2**). Figure S11: One-dimensional NMR spectrum (13C-NMR, 175 MHz, DMSO-*d6*) of the maltosyl-*α*-(1→6)-mangiferin (**2**). Figure S12: Onedimensional NMR spectrum (DEPT-135, 175 MHz, DMSO-*d6*) of the maltosyl-*α*-(1→6)-mangiferin (**2**). Figure S13: Two-dimensional NMR spectrum (1H-13C HSQC, 700 MHz, DMSO-*d6*) of the maltosyl*<sup>α</sup>*-(1→6)-mangiferin (**2**). Figure S14: Two-dimensional NMR spectrum (1H-13C HMBC, 700 MHz, DMSO-*d6*) of the maltosyl-*α*-(1→6)-mangiferin (**2**). Figure S15: Two-dimensional NMR spectrum (1H- 1H COSY, 700 MHz, DMSO-*d6*) of the maltosyl-*α*-(1→6)-mangiferin (**2**). Figure S16: Two-dimensional NMR spectrum (1H-1H NOESY, 700 MHz, DMSO-*d6*) of the maltosyl-*α*-(1→6)-mangiferin (**2**).

**Author Contributions:** Conceptualization: T.-S.C.; data curation and methodology: Y.-L.T., T.-S.C. and H.-Y.D.; project administration: T.-S.C. and J.-Y.W.; writing—original draft, review, and editing: T.-S.C., T.-Y.W., J.-Y.W., H.-J.T. and H.-Y.D. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Ministry of Science and Technology of Taiwan under grant number MOST 110-2221-E-024-002 to T.-S.C. and grant number MOST 110-2221-E-507-002 to J.-Y.W.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available in the article or supplementary material.

**Conflicts of Interest:** The authors declare no conflict of interest.
