K-085. Preferential Glycosylation of 7-Hydroxyl Group of Puerarin by Microbacterium oxydans CGMCC 1788

S. Yuan1, J-R. Jiang1, J-F. Ding1, S-C. Zhu1, H-D. Xu1, W-P. Xu1, H. Ye1, Y-J. Dai1, X-D. Cong2;
1Nanjing Normal Univ., Nanjing, CHINA, 2Jiangsu Lianchuang Meditech Co.,Ltd, Nanjing, CHINA.

Background: Puerarin, the most abundant isoflavone in Puerariae radix, is prescribed to treat coronary heart diseases, angina pectoris, cardiac infarction, problems in ocular blood flow. However, puerarin’s solubility is too low to be given by injection. Therefore, we tried to find some microbes for modification of puerarin to develop new, highly soluble and bioactive puerarin derivatives. Methods: Transformation of puerarin was done by resting cells. The structure of procucts was identified by IR, ESI-TOF-MS, 1H, 13C NMR, 2D-NMR spectroscopic. Results: Puerarin was glycosylated by Microbacterium oxydans CGMCC 1788 to its two novel O-glycosides in which the hydrolysable sugar is attached preferentially to a phenolic hydroxy group via an unreported O-glucosylation of 7-hydroxyl group of puerarin. The structures of the glycosides were characterized as puerarin-7-O-glucopyranoside and puerarin-7-O-isomaltoside by electrospray ionization time-of -flight mass spectrometry and nuclear magnetic resonance techniques. The apparent solubility of Puerarin-7-O-glucopyranoside and Puerarin-7-O-isomaltoside were 0.21M and1.21M, respectively, and about 18 and 100 times that of natural puerarin. The plasma concentration-time curve, pharmacokinetic parameters of puerarin-7-O-glucoside in rat by intravenous injection showed that the half time (t1/2) and mean repair time (MRT) of puerarin-7-O-glucoside were 13.40±2.70min and 31.50±3.60min, respectively,whereas the half time (t1/2) and mean repair time (MRT) of puratin were 4.70± 1.13min and 16.42±2.37min. The endothelium-independent vasorelaxant effect of puerarin-7-O-glucoside on rat thoracic aorta was similar to effect of natural puerarin in vitro. Conclusion: The presented novel puerarin O-glycosides derivatives show better potential for development of new pharmaceutical to treat heart diseases in the future.