Application of amylomaltase for the synthesis of salicin-α-glucosides as efficient anticoagulant and anti-inflammatory agents

• An enzymatic process has been developed for the synthesis of salicin-α-glucosides.
• Amylomaltase can synthesize salicin-α-glucosides with long-chain oligosaccharides.
• The main products are salicin-α-D-glucopyranoside, salicin-α-D-maltopyranoside and salicin-α-D-maltotriopyranoside.
• The glucosylated salicin derivatives exhibited biological activities.

The focus of this study was the synthesis of α-glucosyl derivatives of salicin by a transglucosylation reaction. The reaction was catalyzed by recombinant amylomaltase using tapioca starch as a glucosyl donor. Several reaction parameters, such as the enzyme-substrate concentrations, pH, temperature and incubation time, were optimized. Using the optimum conditions, at least three products with retention times (Rt) of 6.2, 9.2 and 14.1 were observed. The maximum yield of glucosylated salicin derivatives was 63% (w/w) of the total products. The structures of the glucosylated salicin derivatives were confirmed to be salicin-α-D-glucopyranoside, salicin-α-D-maltopyranoside and salicin-α-D-maltotriopyranoside through a combination of enzyme treatments, mass spectrometry and NMR analyses. The glycosidic bond between glucose units consisted of an α-1,4-configuration. The water solubility of salicin-α-D-glucopyranoside, salicin-α-D-maltopyranoside and salicin-α-D-maltotriopyranoside was 3-, 5- and 8-fold higher, respectively, than that of salicin, whereas their relative sweetness values were lower than that of sucrose. Interestingly, the long-chain salicin-α-D-glucosides showed greater anticoagulant and anti-inflammatory activities than salicin. In addition, the synthesized salicin-α-D-glucosides were able to tolerate acidic and high temperature conditions, but not α-glucosidase or human digestive enzymes. Therefore, these salicin-α-D-glucosides should be applied by the injection route to achieve greater bioavailability than is possible by the oral route.

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