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.