In this report, alpha-isosalicin, a potent anticoagulant and skin whitening agent, was synthesized by a highly efficient chemoselective and diastereoselective reaction, catalyzed by maltase from bakers' yeast (Saccharomyces cerevisiae). The highest yield of this one-step transglucosylation reaction was achieved with 50 mM of salicyl alcohol as a glucose acceptor. The key reaction factors were optimized using response surface methodology (RSM) with an enzyme concentration of 10 U/mL. The optimum temperature of the reaction was determined as 36.5 degrees C, the optimal maltose concentration was 40% (w/v), the optimal pH was 6.5, and the optimal reaction time was 16 h. Under these conditions 75% of alpha-isosalicin was obtained, with a yield of 10 g/L, and no by product formation was observed. (C) 2011 Elsevier Ltd. All rights reserved.