Protective effects of Phytohustil^® on primary human keratinocytes in vitro

Introduction Althaea officinalis L. (A. officinalis, common name marshmallow) has been known from ancient times for the treatment of diseases such as dry cough caused by irritation of the oral and pharyngeal mucosa [1].

Extracts of marshmallow root form a protective film on the inflamed mucosa. Although, limiting the effects only to the mucilaginous effects of polysaccharides is not enough to explain the properties of A. officinalis [1]. Non-keratinized stratified squamous epithelium covers the oropharyngeal mucosa. Keratinocytes act as the major barrier to external environmental irritants or their metabolites directly and/or indirectly driving the production of pro-inflammatory, reactive oxygen species (ROS) [3].

Aim and Methods The aim of this project is to investigate the anti-inflammatory, anti-oxidative properties of Phytohustil^® cough syrup (STW 42) on undifferentiated normal human epidermal keratinocytes (NHEK).

Results Treatment of NHEK with Phytohustil^® or root extract of A. officinalis with 50 to 1000 µg/ml for either 24 h or 48 h revealed no significant loss of viability by PrestoBlue^® (PB) assay. Pro-inflammatory stimulation of NHEK with LPS (50 μg/ml) induced a significantly increased IL-1β release quantified by ELISA by 67.4 % compared to the negative control. Pre-treatment with Phytohustil^® significantly inhibited the LPS-induced IL-1β release by 21.9 % (100 μg/ml), 35.3 % (200 μg/ml) and 18.1 % (400 μg/ml) in comparison with LPS-stimulated NHEK. Pre-treatment with root extract of A. officinalis at a concentration of 100 μg/ml significantly inhibited the IL-1β release by 34.9 % compared to the negative control. A. officinalis root extract significantly inhibited the amount of H₂O₂-induced ROS production in NHEK treated with 400 μM H₂O₂.

Discussion and Conclusion Our results indicate that Phytohustil^® and the root extract of A. officinalis protect NHEK against the cytotoxic effects of H₂O₂ and against the LPS-pro-inflammatorily induced IL-1β-release. The root extract of A. officinalis could be identified as a strong antioxidant by inhibition of the ROS production after pro-oxidative treatment of NHEK with H₂O₂. These reparative/protective properties may support the positive influence of Phytohustil^® used for therapy of irritated and inflamed throat tissue and cough.

Disclosure J.M. ist Mitarbeiter der Steigerwald Arzneimittelwerk GmbH, Darmstadt. Die Studie wurde von der Steigerwald Arzneimittelwerk GmbH, Darmstadt, unterstützt.

Publication History

Article published online:
22 June 2021

• References

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