Gentiana lutea is a herbal bitter drug that is used to enhance gastrointestinal motility and secretion. Recently we have shown that amarogentin, a characteristic bitter compound of Gentiana lutea extract (GE), binds to the bitter taste receptors TAS2R1 and TAS2R38 in human keratinocytes, and stimulates the synthesis of epidermal barrier proteins. Here, we wondered if GE also modulates lipid synthesis in human keratinocytes. To address this issue, human primary keratinocytes were incubated for 6 days with GE. Nile Red labeling revealed that GE significantly increased lipid synthesis in keratinocytes. Similarly, gas chromatography with flame ionization detector indicated that GE increases the amount of triglycerides in keratinocytes. GE induced the expression of epidermal ceramide synthase 3, but not sphingomyelinase. Lipid synthesis, as well as ceramide synthase 3 expression, could be specifically blocked by inhibitors of the p38 MAPK and PPARγ signaling pathway. To assess if GE also modulates lipid synthesis in vivo, we performed a proof of concept half side comparison on the volar forearms of 33 volunteers. In comparison to placebo, GE significantly increased the lipid content of the treated skin areas, as measured with a sebumeter. Thus, GE enhances lipid synthesis in human keratinocytes that is essential for building an intact epidermal barrier. Therefore, GE might be used to improve skin disorders with an impaired epidermal barrier, e.g., very dry skin and atopic eczema.

The anti-inflammatory properties of the topical herbal composition VEL-091604 with gentian root, licorice root, and willow bark extract were assessed in a randomized, prospective, placebo-controlled, double-blind ultraviolet (UV)-erythema test study with 42 healthy volunteers in comparison to 1% hydrocortisone acetate. The efficacy and tolerability of VEL-091604 cream 2 times daily over 2 wk was evaluated in an open-label, prospective proof of concept study in 10 subjects with atopic dermatitis using a lesional SCORAD severity score. In the UV-erythema test VEL-091604 cream significantly reduced inflammation compared to placebo and was as effective as 1% hydrocortisone acetate. The clinical study with atopic subjects revealed a significant and rapid reduction of the lesional SCORAD severity score in the test areas after 1 and 2 wk. No adverse events were recorded. It is concluded that the herbal cream VEL-091604 with licorice root, willow bark, and gentian root extract display anti-inflammatory properties in vivo. It is a promising new treatment option for atopic dermatitis that warrants further investigation in controlled studies.