LC-MS/MS ANALYSIS OF SUGARCANE EXTRACTS AND DIFFERENTIATION OF MONOSACCHARIDES MOIETIES OF FLAVONE C-GLYCOSIDES

Abstract

LC-MS/MS data of the flavones from extracts of nonmodified and transgenic sugarcane (“Bowman-Birk” and “Kunitz”) led to the proposition of characteristic fragmentations that can be applied to identify the monosaccharides glucose, arabinose, and rhamnose in C-glycosylflavones. Collision-induced dissociation (CID) MS/MS generated diagnostic ions for different linked sugars in C-glycosylflavone–O-glycoside and C-glycosylflavone–O-acid derivatives, and the combination of MS data with postcolumn derivatization using UV shift reagents (which provide complementary information to determine the substitution patterns in the flavone skeleton) allowed for the identification of seven flavones not previously reported in sugarcane: 6-methoxyluteolin-8-C-arabinosyl-7-O-glucoside; diosmetin-8-C-arabinosyl-7-O-arabinoside; vitexin-7-O-rhamnoside; diosmetin-8-C-rhamnosyl-7-O-glucoside; tricetin-8–C-(6‴-O-sinapoylglucoside); 7,4′ di-O-methylapigenin-8-C-arabinosyl-rhamnoside; and luteolin-8-C-rhamnosyl-7-O-rhamnoside.

Keywords:

• CID-MS/MS
• flavonoids
• LC-UV-MS
• postcolumn derivatization
• sugarcane
• transgenic plants

ACKNOWLEDGMENT

The authors wish to thank Prof. Dr. Márcio de Castro Silva-Filho (ESALQ-USP) for furnishing transgenic sugarcane samples. This work was supported by Brazilian agencies FAPESP (Proc. 00/11645-2, 02/00493-2, and 06/59457-6) and CNPq and also by The Swiss National Science Foundation.

Notes

sh = shoulder.