Using ion mobility 2D separation and specificity as a routine strategy to enhance profiling of complex medicinal plant extracts

Several Passiflora (Passifloraceae) species are utilized as phytomedicines (sedative/tranquillising), due to their flavonoids, mainly C-glycosylflavones (apigenin and luteolin derivatives; frequently occurring as isomers), but only a few species are commercially exploited [1]. A non targeted screening strategy comprising the combined peak capacity of UPLC/ion mobility and collision cross section (CCS) measurements has been investigated as a strategy to produce routine unequivocal identification of marker flavonoid isomers in complex medicinal plant extracts. The phytochemical screening of Passiflora alata, P. edulis, P. incarnata and P. caerulea leaf extracts using ion mobility mass spectrometry has enabled generation of a “known” and “known unknowns” reference CCS speciation finger print profile, which has been incorporated into a MS/CCS library. Utilising standards, reference CCS of 6-C/8-C-glycosylflavone isomer pairs orientin/isoorientin (187.7 Ǻ²/198.1 Ǻ²) and vitexin/isovitexin (188.8 Ǻ²/195.5Ǻ²) have been generated. The isomer CCS specificity has enabled unique deconvoluted isomeric quantitation of chromatographically coeluting isomers to be performed. The individual calculated concentrations of coeluting isoorientin and orientin in Passiflora extracts have been determined and compared to a conventional mass spectrometry approach. The enhanced peak capacity ([Fig. 1 ]) enabled more information to be extracted from fragmentation studies and the individual fragmentation spectra have been obtained for flavonoid isomers which are co-eluting with structurally related compounds.

The screening approach investigated illustrates the potential to enhance specificity when profiling phytochemical make-up in medicinal plants, where CCS values for knowns/ known unknowns and highly specific ion mobility product ions can be generated for all analytes in a single acquistion.

Fig.1 Retention time (Rt) vs ion mobility separation (Dt)

• References

• 1 Zeraik ML, Yariwake JH. Quantification of isoorientin and total flavonoids in Passiflora edulis fruit pulp by HPLC-UV/DAD. Microchem J 2010; 96: 86-91