Potent bacterial neuraminidase inhibitors, anthraquinone glucosides from Polygonum cuspidatum and their inhibitory mechanism

International Conference and Exhibition on Marine Drugs and Natural Products

July 25-27, 2016 Melbourne, Australia

Zuopeng Li, Zia Uddin and Ki Hun Park

Gyeongsang National University, Republic of Korea

Posters & Accepted Abstracts: J Pharmacogn Nat Prod

Abstract :

The roots of P. cuspidatum are used as popular food stuff for inflammation that has deep relation with bacterial neuraminidase (BNA). Methanol extract showed significant BNA inhibition (50 �¼g per ml) and mainly consisted of chromophoric polyphenols, which are analyzed by chromatographic isolation and UPLC-PDA-Q-TOF/MS. The principal BNA inhibitory compounds (2-6) were identified as emodin (2), physcion-8-O-�²-D-glucopyranoside (3), emodin-8-O-�²-D-glucopyranoside (4), emodin-1-O-�²-Dglucopyranoside (5) and 2-methoxy-6-acetyl-7-methyljuglone (6). Interesting facets was that anthraquinone glucosides (3-5) showed 10-fold more potent inhibition than the corresponding aglycones (1 and 2). For example emodine (2) showed 5.4 �¼M of IC50, while its glucosides (4 and 5) had IC50 values of 0.85 �¼M and 0.43 �¼M respectively. Similar trend was observed on physcion (1, IC50>200 �¼M) and its glucoside (3, IC50=6.2 �¼M). Kinetic behaviors were fully characterized with the changes of Km and Vmax, the ratios of KI/KIS and Kik/Kiv, and fluorescence quenching effect. The anthraquinone (2) was mixed type I inhibitor, while its glucosides (3 and 5) were noncompetitive ones. The affinity constants (KSA) of inhibitors increased in proportion to their inhibitory potencies. Furthermore the most active neuraminidase inhibitors were proven to be present in higher quantities in the native roots.

Biography :

Zuopeng Li is currently a PhD student in the Division of Applied Life Science, Gyeongsang National University, Republic of Korea.

Email: dameng2010@126.com