RESULTS
The Q-TOF-LC/MS analysis of the Paulownia Clon in Vitro 112 leaf extract
shows that the main metabolite, was the verbascoside (acteoside) which
belongs to the phenylethanoid glycosides. Also, iridoids such as
catalpol, 7-hydroxytomentoside and aucubin, as well as flavonoids:
glycosides of luteolin, kaempferol and apigenin, were found (figure 1).
Multi-step chromatographic separation led to the isolation of several
polyphenolic constituents - derivatives of a disaccharide
α-L-rhamnopyranosyl(1→3)-D-glucopyranose – verbascoside
[1 ], verbascoside [2 ] and cistanoside F
[3 ], and a glycosylated flavone clerodendrin – apigenin
7-O-[β-D-glucuronopyranosyl(1→2)-β-D-glucuronopyranoside]
[4 ], but also 2 iridoid glycosides – catalpol
[5 ](as a mixture) and 7-hydroxytomentoside [6 ]
(figure 2). Their identity was confirmed by means of accurate mass
measurements, MS/MS fragmentation patterns, ultraviolet-visible (UV-vis)
spectra, 1D and 2D NMR (nuclear magnetic resonance) spectroscopy, and by
comparison with existing literature data. The data are in the
Supplementary Material.
The UHPLC-ESI-MS/MS method was used to determine the content of
individual compounds in leaves, twigs, flowers and fruits of Paulownia
Clon in Vitro. All verbascoside derivatives, including cistanoside F,
were determined as equivalent of verbascoside, while all flavonoids were
determined to be
apigenin-7-O-glucuronopyranosyl(1→2)-glucuronopyranoside equivalent
(table 1). The concentrations of the individual compounds were
determined according to the calibration curves of standards (Table 1),
and classes of the individual compounds in Table 2 were created by
summing up the concentrations of individual compounds.