Ultrasound-promoted enzymatic synthesis of troxerutin esters in nonaqueous solvents.
Comparative studies of enzymatic acylation of troxerutin by the alkaline protease from Bacillus subtilis under ultrasound and shaking were carried out in nonaqueous media. Using divinyl dicarboxylates (CH(2)CH-OOC-(CH(2))(n)-COO-CHCH(2), n=2, 3, 4, 7, 8, 11) featuring different chain length as acyl donors, troxerutin was regioselectively acylated at B ethoxyl group, whether under ultrasound or shaking. Ultrasonic treatment increased the reaction rate and led to high conversion. Several factors, such as pre-irradiation on the enzyme, the power and frequency of the ultrasound, operation manner, as well as the length of the acyl donors were investigated. Using enzyme pre-irradiated for 8 h, the conversion of troxerutin was increased to 87.3% compared with 56.3% obtained from the untreated enzyme. Experimental results also showed that continual ultrasound caused greater rate acceleration than interval ultrasound. Powers of 100, 150 and 200 W, frequencies of 40, 80 and 100 kHz all showed significant improvement on the transesterification, with the greatest effect observed at 150 W, 80 kHz. The acceleration effect increased as the chain length of the acyl donors decreased from C(13) to C(4).
Xiao
Yongmei
Y
College of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, People's Republic of China. henangongda@yahoo.com
Yang
Liangru
L
Mao
Pu
P
Zhao
Zhen
Z
Lin
Xianfu
X
D001412:Bacillus subtilis / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D004952:Esters / Q000138:chemical synthesis* / Q000737:chemistry; D006896:Hydroxyethylrutoside / Q000031:analogs & derivatives* / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D014465:Ultrasonics
D001426:Bacterial Proteins; D004952:Esters; D006896:Hydroxyethylrutoside; D012997:Solvents; C005865:troxerutin; D010450:Endopeptidases; C087822:alkaline protease