Synthesis, Structural Characterization, and Biological Properties of Pentyl- and Isopentyl-α-D-Glucosides

The study was devoted to the synthesis of pentyl glucosides (PenGn) and isopentyl glucosides (IsoPenG(n)) by transglycosylation using recombinant cyclodextrin glycosyltransferase from Bacillus circulans A11, beta-cyclodextrin as a glucosyl donor and 1-pentanol and isopentanol as acceptors. TLC and MS analysis indicated at least 3 products which were in accordance with PenGn and IsoPenGn having glucose, maltose and maltotriose attached to the alkyl groups of both alcohols. Two products of each glucoside were purified by preparative TLC and their structures were identified by NMR technique to be pentyl-alpha-D-glucopyranoside (PenG(1)), pentyl-alpha-D-maltopyranoside (PenG(2)), isopentyl-alpha-D-glucopyranoside (IsoPenG(1)) and isopentyl-alpha-D-maltopyranoside (IsoPenG(2)). The effect of water-in-hexadecane emulsion on emulsion-forming properties showed that PenG(2) had the highest emulsifying activity. Adding PenG(2) to the insoluble Corynebacterium glutamicum amylomaltase from Escherichia coli transformants (A406R), helped to perform it to more soluble conformation. Moreover, it was found that PenG(1,2) exhibited a higher antibacterial activity against E. coli ATCC 25922 than that of IsoPenG(1,2). Hence, the biological properties of the synthesized products may be useful for their applications as emulsifying, solubilizing and antibacterial agents.