Introduction
The recently discovered olfactory receptors on skin cells paved the way to develop cosmetic active ingredients which stimulate those receptors and drive keratinocyte differentiation and maturation. It is therefore easy to understand, how fragrances and scents can not only stimulate the brain but also the skin. However, the subset of olfactory receptors on the skin seems to be limited. Some scents do not activate olfactory receptors in keratinocytes but bitter taste receptors, a closely related receptor class. We developed a scenting cosmetic active ingredient from the resurrection bush Myrothamnus flabellifolia (INCI: Caprylic/Capric Triglyceride, Myrothamnus Flabellifolia Leaf/Stem Extract) which reduces cortisol levels of stressed persons by activating olfactory receptors in the nose at subconcious levels and improves the skin condition by activating bitter taste receptors on keratinocytes.

Methods
Characterisation of the scent profile has been done with a panel of 12 trained people. The composition of the essential oil fraction was determined by HPLC / GC-MSD.
To stress study participants, a negative OASIS image set was used. Stress levels were investigated by use of a positive and negative affect schedule (PANAS) and measurement of stress hormones (cortisol and alpha-amylase). In addition, an electro encephalogram was recorded to determine the fraction of alpha-waves which represent a relaxed mood.
Skin parameters were assessed with corresponding instruments (cutometer, corneometer, glossymeter, colorimeter). Skin hydration was measured by assessing 53 spots on the face and a computer-matched moisturization map was created, showing the moisture distribution on the whole face.
Investigation of olfactory or bitter taste receptor activation on keratinocytes was assessed by measuring the calcium influx and the cAMP level.

Results
The active ingredient has a characteristic odour profile with pine, herbal and citrus notes. It was able to destress stressed people as judged by the PANAS questionnaire and the stress hormone level. The skin's moisture was increased and showed a more even distribution. Additionally, the overall aspect of the skin improved, leading to an improved skin radiance and complexion. The in-vitro experiments suggests that the activation of the keratinocytes is not driven by olfactory receptors but by bitter taste receptors as the cAMP level was not elevated.

Discussion / Conclusion
It has long been known that scents have a positive effect on people's state of mind. Scent therapies can have a relaxing or invigorating effect. In recent years, more and more olfactory and bitter taste receptors have been detected on the surfaces of skin cells, especially in keratinocytes. We have shown that a cosmetic ingredient with a pine, herbal and citrus fragrance profile can calm the mind as well as the skin. The level of stress hormones was immediately reduced and the skin became more even and radiant. Interestingly, the keratinocytes are not activated via olfactory receptors, but via bitter taste receptors. Thus, the cosmetic active ingredient can unfold its full potential via olfactory receptors in the nose as well as via bitter taste receptors on the skin and appeals to people with all their senses.