Enzyme-Catalyzed Glycosylation of Curcumin and Its Analogues by Glycosyltransferases from Bacillus subtilis ATCC 6633

Abstract

Curcumin is a naturally occurring polyphenolic compound that is commonly used in both medicine and food additives, but its low aqueous solubility and poor bioavailability hinder further clinical applications. For assessing the effect of the glycosylation of curcumin on its aqueous solubility, two glycosyltransferase genes (BsGT1 and BsGT2) were cloned from the genome of the strain Bacillus subtilis ATCC 6633 and over-expressed in Escherichia coli. Then, the two glycosyltransferases were purified, and their glycosylation capacity toward curcumin and its two analogues was verified. The results showed that both BsGT1 and BsGT2 could convert curcumin and its two analogues into their glucosidic derivatives. Then, the structures of the derivatives were characterized as curcumin 4 -O-β-D-glucoside and two new curcumin analogue monoglucosides namely, curcumoid-O-α-D-glucoside (2a) and 3-pentadienone-O-α-D-glucoside (3a) by nuclear magnetic resonance (NMR) spectroscopy. Subsequently, the dissolvability of curcumin 4 -O-β-D-glucoside was measured to be 18.78 mg/L, while its aglycone could not be determined. Furthermore, the optimal catalyzing conditions and kinetic parameters of BsGT1 and BsGT2 toward curcumin were determined, which showed that the Kcat value of BsGT1 was about 2.6-fold higher than that of BsGT2, indicating that curcumin is more favored for BsGT2. Our findings effectively apply the enzymatic approach to obtain glucoside derivatives with enhanced solubility.

Biosynthesis of Three Chalcone β-D-glucosides by Glycosyltransferase from Bacillus subtilis ATCC 6633

“…SDS-PAGE analysis showed that the molecular weight of the protein was about 44 kDa (Fig. 1) determined by protein marker, which was the same as our previous verification [9].…”

“…Compared with GTs from plants, microbial GTs generally exhibit remarkable substrate universality [13,14]. Our previous study has proved that BsGT1 from B. subtilis ATCC 6633 had excellent glycosylation ability toward curcumin and analogs [9]. The glycosylation of three chalcone derivatives demonstrated its substrate promiscuity again.…”

“…In our previous study, BsGT1 from Bacillus subtilis ATCC 6633 was identified to catalyze the glycosylation of curcumin and analogs [9] and in this study three chalcone glycosides with methoxy, methyl, and hydroxyl groups substituted on the benzene ring were employed as the substrates to explore its catalytic capability on chalcones. Furthermore, we overexpressed two key enzymes, phosphoglucomutase (PGM) and uridine diphosphate glucose pyrophosphorylase (GalU), involved in the pathway of uridine diphosphate glucose (UDP-Glc) synthesis in E. coli and successfully improved the efficiency of biosynthesis of chalcone glycosides by BsGT1 in the whole-cell system.…”

Biocatalytic Synthesis of a Novel Bioactive Ginsenoside Using UDP-Glycosyltransferase from Bacillus subtilis 168

“…Despite both PPD and PPT skeletons containing the C12 hydroxyl group, ginsenosides with sugar moieties attached to the C12 hydroxyl group have never been identified from Panax species. Compared with plant-derived UGTs, microbial UGTs generally exhibit remarkable aglycone flexibility and poor regiospecificity [13][14][15][16][17][18]. These promiscuous UGTs could be exploited as robust biocatalysts for glycodiversification of natural and unnatural products for new drug discovery [19,20].…”

Synthesis of N-Glycosyl-2-oxindoles by Pd-Catalyzed N-Arylation of 1-Amidosugars

“…Other 2-oxindole derivatives are also under clinical trials against various diseases. 3 The incorporation of a sugar moiety in bioactive molecules may have several benefits such has enhancing their bioavailability, 4 their solubility 5 or their biological activity by targeting for example, selectively cancer tissues through the Warburg effect. 6 Such a transformation was achieved in the 2-oxindole series, by chemical synthesis, 7 and recently by biotransformation using Streptomyces sp.…”