Lamalbid, Chlorogenic Acid, and Verbascoside as Tools for Standardization of Lamium album Flowers-Development and Validation of HPLC-DAD Method

Abstract

Preparations from the flowers or herb of the white dead nettle (Lamium album L.) are recommended for the treatment of upper respiratory tract disorders or as a topical medication for mild inflammation of the throat, mouth, and skin. Taking into consideration the significance of L. album in traditional medicines across Europe, as well as the lack of studies describing the quantities of their most abundant constituents, we aimed to design a high-performance liquid chromatography coupled with diode-array detection (HPLC-DAD) method for potential standardization procedures of extracts from flowers of L. album. The HPLC-DAD method was developed and validated for quantification of iridoids (lamalbid), phenolic acids/depsides (chlorogenic acid), phenylpropanoids (verbascoside), and flavonoids (rutin; quercetin malonylhexoside; tiliroside) in aqueous and ethanolic-aqueous extracts of Lamii albi flos. The method was specific, accurate, and precise. Lamalbid was the most abundant compound both in aqueous (39.09 ± 1.02 m/g dry weight) and ethanolic-aqueous (26.66 ± 0.64 m/g dry weight) extracts. The quantities of selected compounds, except for chlorogenic acid and tiliroside, were higher in the aqueous extract than in the ethanolic-aqueous one. In conclusion, the method developed allowed for quantitation of compounds from different classes. In particular, chlorogenic acid and verbascoside have been proposed as reference compounds for routine quantitative control of Lamii albi flos.

Keywords: HPLC–DAD; Lamiaceae; iridoids; phenolic acids; phenylpropanoids.

Figure 1

Structures of compounds selected for quantitation with high-performance liquid chromatography coupled with diode-array detection (HPLC–DAD) method.

Figure 2

HPLC–DAD chromatograms of ethanolic-aqueous extract detected at: 240 nm (a), 320 nm (b), 350 nm (c); 1—lamalbid, 2—caryoptoside, 3—chlorogenic acid, 4—rutin, 5—lamiuside A, 6—verbascoside, 7—quercetin malonylhexoside, 8—tiliroside.