From bench to counter: Discovery and validation of a peony extract as tyrosinase inhibiting cosmeceutical.

The anti-melanogenic principle of peony (Paeonia officinalis subsp. officinalis) seeds was elucidated via activity-guided isolation. Resveratroloside (trans-resveratrol-4'-O-beta-d-glucopyranoside) was found to be the main metabolite of P. officinalis subsp. officinalis seeds and its tyrosinase inhibiting activity was confirmed via an enzymatic assay. Furthermore, the in vitro activity and the therapeutic window were studied employing the murine melanoma cell line B16F10. The results from the conducted stability assay and the high content of resveratroloside in the seeds (i.e. 10.4% dw) motivated us to push the extract forward to an in vivo tolerance assay. A clinical study with forty Caucasian participants proofed a good skin-tolerance with high moisture effect and reduction of pores.

Identification of the NADPH Oxidase 4 Inhibiting Principle of Lycopus europaeus.

NADPH oxidase 4 (Nox4) has recently been implicated as driving force in cellular senescence. Thus, there is growing interest to develop Nox4 inhibitors, which might be valuable agents for cosmeceutical applications. Alpine plants represent a valuable source for the identification of novel bioactive natural products with anti-ageing effects, especially substances that protect plants against UV radiation, which is also known to contribute to the ageing of human skin. Therefore, the aim of this study was to identify novel Nox4 inhibitors from alpine plants. Within an initial screening of extracts of alpine plants on their ability to inhibit Nox4 activity in HEK cells, the methanolic extract of the subaerial parts of Lycopus europaeus showed a strong inhibition of Nox4 (81% chemiluminescence quenching) and a simultaneously high cell viability (91% vitality). Rosmarinic acid was isolated and identified as the major compound in this bioactive extract. It showed a dose dependent inhibitory activity on Nox4 with an IC50 of 1 µM. Moreover, it also showed a significant inhibitory activity on Nox2 in the low micromolar range, whereas no inhibition of Nox5 was detected. Further investigations confirmed that the observed effects of rosmarinic acid on Nox2 and Nox4 are real inhibitory activities, and not due to ROS scavenging effects. Therefore, L. europaeus, which we demonstrated to be a good source of rosmarinic acid, has great potential for usage in cosmeceutical products with anti-ageing activity.