Ariya Nanetoe, Jirarut Wongkongkatep, Pranee Inprakhon, and Nisa Patikarnmonthon
Dextran is homopolysaccharide produced by microorganism. It is soluble in water and polar organic solvents. Dextran have been widely used in medical applications such as blood plasma extenders, hypovolemia, and drug carrier, according to its low cytotoxicity and biodegradability.
The aim of this study is to prepare the amphiphilic dextran by addition of hydrophobic group to dextran for further use as drug carrier. Modification of dextranwas done through transesterification process by lipase AY from Candida rugosa that was treated with 18-crown-6 ether to enhance the enzyme stability. The result showed that the enzyme activity of treated lipase is increased from 5299.6±202 µmol of fatty acid/h to 28971±858 µmol of fatty acid/h. The modified dextran was enzymatically prepared, by adding vinyl laurate onto dextran in DMSO at 50oC with presence of treated lipase. The degree of substitution (%DS) of the modified dextran was determined by 1H-NMR spectroscopy. The %DS are 49.97% and 66.84% in the reactions performed at the ratio of dextran to vinyl laurate as 1:2 and 1:4, respectively. This suggests the optimal ratio of dextran to vinyl laurate of this study is 1:4. In addition, %DS is slightly increased from 66.84% to 71.55% by stepwise addition of lipase enzyme.
Keyword : Dextran, Lipase, Hydrophobicity, Transesterification