Enzymatic Synthesis of Novel Vitexin Glucosides

Abstract

Vitexin is a C-glucoside flavone that exhibits a wide range of pharmaceutical activities. However, the poor solubility of vitexin limits its applications. To resolve this limitation, two glycoside hydrolases (GHs) and four glycosyltransferases (GTs) were assayed for glycosylation activity toward vitexin. The results showed that BtGT_16345 from the Bacillus thuringiensis GA A07 strain possessed the highest glycosylation activity, catalyzing the conversion of vitexin into new compounds, vitexin-4′-O-β-glucoside (1) and vitexin-5-O-β-glucoside (2), which showed greater aqueous solubility than vitexin. To our knowledge, this is the first report of vitexin glycosylation. Based on the multiple bioactivities of vitexin, the two highly soluble vitexin derivatives might have high potential for pharmacological usage in the future.

Vitexin‐loaded poly(ethylene glycol) methyl ether‐grafted chitosan/alginate nanoparticles: preparation, physicochemical properties and in vitro release behaviors

“…While the visible swelling of vitexin‐loaded mPEG‐ g ‐CTS/ALG nanoparticles was less in the pH 11 buffer solution than in the pH 3 and 7 buffer solutions, their significantly faster vitexin release was mainly due to dissolution in high‐pH medium. Wu et al 13 . reported that vitexin's solubilities in pH 6 and 8 phosphate buffers and deionized water (pH 7) were 7.1, 157.3 and 37.2 mg L −1 , respectively.…”

“…Recently, it has received increasing attention due to its antioxidant, 1,6 anti‐inflammatory, 6,7 antinociceptive, 6 antimetastatic, 8 antitumor, 8 antibiofilm and antibacterial 9 properties. However, its poor water solubility, poor absorption in the gastrointestinal tract and low oral bioavailability limit its clinical and therapeutic applications 10‐15 …”

Enzymatic synthesis of vitexin glycosides and their activity

“…Glycosylation with glycosidases is under thermodynamic control using a non-activated sugar donor, which made these enzymes attractive in the low-cost synthesis of glycosides. 18 Enzymatic synthesis of vitexin glucosides has been reported by Chang; 19 two glycosidases and four glycosyltransferases were selected to glycosylate vitexin. The glycosyltransferase (BtGT_16345) from Bacillus thuringiensis showed glycosylation activity, catalyzing the conversion of vitexin-4′- O -β-glucoside (17.5% yield) and vitexin-5- O -β-glucoside (18.6% yield).…”

“…The glycosyltransferase (BtGT_16345) from Bacillus thuringiensis showed glycosylation activity, catalyzing the conversion of vitexin-4′- O -β-glucoside (17.5% yield) and vitexin-5- O -β-glucoside (18.6% yield). 19 However, the glycosidases (amylosucrase and maltogenic amylase) did not catalyze the glycosylation of vitexin. 19 The reported enzymatic glycosylation of vitexin is not efficient with lower yields mainly due to the poor solubility issue of the substrate.…”

“… 19 However, the glycosidases (amylosucrase and maltogenic amylase) did not catalyze the glycosylation of vitexin. 19 The reported enzymatic glycosylation of vitexin is not efficient with lower yields mainly due to the poor solubility issue of the substrate. The above results indicate that efficient glycosylation of vitexin is still more challenging for glycosyltransferases and glycosidases.…”