LC-UV-electrospray-MS-MS mass spectrometry analysis of plant constituents inhibiting xanthine oxidase.
OBJECTIVE
A previous screening showed that Amyema scandensi [corrected] Danser (Loranthaceae) efficiently inhibited XOD. The aim of this study was to identify the compounds with anti-XOD properties. For this purpose, Electrospray Tandem Mass Spectrometry (ESI-MS-MS) coupled with UV and Diode Array LC techniques were employed.


METHODS
Leaves were delipidized with petroleum ether and extracted with acetone:water 70:30, v:v. The extract was fractionated into the ethyl acetate and water soluble phases. Chemical investigation was performed following the bioactivity guided fractionation. Two fractions with anti-XOD activity were isolated by silica gel column chromatography of the ethyl acetate phase and analyzed by LC-UV-ESI-MS-MS.


RESULTS
The compounds identified with authentic standards were: catechin, epicatechin, epicatechin-3-gallate, quercetin-3-O-glucoside, quercetin-3-O-rhamnoside, and isorhamnetin-3-O-glucoside. Other constituents, only partially characterized, were a procyanidin dimer, a procyanidin trimer, three dimers epi/catechine-epi/catechine gallate and isorhamnetin-O-deoxyhexose. The anti-XOD activity was mainly due to galloyl-containing oligomeric proanthocyanidins.


CONCLUSIONS
The coupling of UV Diode Array-HPLC with ESI-MS-MS represents a versatile tool for the rapid characterization of compounds in complex mixtures, avoiding time-consuming previous isolation.
Gariboldi
E
E
Institute of Pharmacological Sciences, Faculty of Pharmacy, University of Milan, Italy.
Mascetti
D
D
Galli
G
G
Caballion
P
P
Bosisio
E
E
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004791:Enzyme Inhibitors / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D010944:Plants / Q000737:chemistry*; D012015:Reference Standards; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors*
D004791:Enzyme Inhibitors; D014969:Xanthine Oxidase