Quality control, phenolic content and in vitro antioxidant potential of orange mullein flower and leaf

Verbascum species are traditionally used in the treatment of respiratory
disorders. Orange mullein (Verbascum phlomoides L.) is one of three species
that are the official source of drug mullein flower (Verbasci flos). Our study aimed
to determine the overall quality of the V. phlomoides flos and V. phlomoides
folium, the contents of polyphenols, tannins, flavonoids, and phenylpropanoid
derivatives alongside the antioxidant capacity of their ethanolic extracts.
Quality control tests were conducted according to monographs of Ph. Eur.
10.0, secondary plant metabolites were quantified spectrophotometrically
while the antioxidant potential was estimated by two complementary methods
(DPPH free radical scavenging and β-carotene bleaching assay). The higher
contents of examined compounds were determined in flower extract although
the leaf extract showed a stronger antioxidant capacity. We can conclude that
Verbascum phlomoides is a rich source of biologically valuable phenolics,
it possesses considerable antioxidant capacity and investigated herbal drugs
fulfill pharmacopeia’s quality requirements.