The active constituents of Lamium album as inhibitors of cytokines secretion in human neutrophils

Preparations from Lamium album aerial parts were traditionally used in the treatment of chronic bronchitis, skin and vaginal inflammations. The plant material has been reported to be the valuable source of phenylpropanoids, such as lamiusides, which have not been identified in this species to date [1]. Phenylpropanoids are considered to possess anti-inflammatory activity as well as antithrombotic, wound healing and cardioprotective properties [2]. The aim of the study was a determination of inhibitory potential of constituents from L. album against the secretion of inflammatory mediators, such as cytokines (IL-8, TNF-α) and reactive oxygen species (ROS) by human neutrophils, which are the cells of immune system involved in the inflammation. The compounds were isolated from L. album as it was previously described [1]. Isolated compounds were identified based on UV-Vis, MS and NMR spectra. The inhibition of ROS production was analyzed after f-MLP (formyl-met-leu-phenylalanine) stimulation, using luminol-dependent chemiluminescence. The effect of extracts on cytokines, such as IL-8 and TNF-α, secretion after LPS-induced stimulation was established using ELISA tests. Among identified compounds from the groups of phenylpropanoids (lamiusides, phlinoside D, verbascoside), iridoids (caryoptoside, lamiridoside) and flavonoids (tiliroside), in particular phenylpropanoids with methyl groups in a caffeoyl moiety exerted efficacy in the inhibition of IL-8 secretion by neutrophils. The cells treated with glucomartynoside, phlinoside D and lamiuside B produced 29.5 ± 7.1%, 52.4 ± 3.9% and 64.7 ± 5.2% of IL-8, respectively, compared to not treated control, whereas they did not inhibit the secretion of TNF-α. Simultaneously, the inhibition of ROS production by identified compounds was determined. In conclusion, the cytokine-release inhibitory activity of the methylated phenylpropanoids is proposed as a potential anti-inflammatory mode of their action.

[1] Czerwińska et al, Planta Med. 2017, DOI: 10.1055/s-0043 – 107031

[2] Di Paola et al, Biochem Pharmacol. 2009, 77: 845 – 857