Issue 23 — November 2000

Issue 23
Category		Title		Author
Congress Report		Quantification of Photon Emission Processes in Cells Influenced by Cosmetic Ingredients		Stefan Benard

Figure: Correlation of UV irradiation - oxidative stress - cell damage and ICL-S (Induced Chemiluminescence of human skin)

In the quantification of interactions between the skin and ultraviolet irradiation, the so-called "oxidative stress", the main cause of premature skin aging (photoaging) caused by "reactive oxygen species" (ROS) has to be mentioned next to erytheme formation, namely acute damage caused by UV rays.

As defense mechanism all cells dispose of enzymatic and non-enzymatic mechanisms to deactivate the increased formation of ROS in so far that the cellular homeostasis is maintained under normal conditions.

Suberythemal doses of UV rays are, however, capable of weakening this endogenous antioxidative system. The excessive energy which is released in these oxidative processes is released in the form of protons (chemiluminescence) and correlates with the extent of the damage.

By using a newly developed Single-Photon-Counting-System it is possible to measure the induced chemiluminescence of human skin (ICL-S) immediately after sun exposure and to test the influence of cosmetic ingredients.

Main emphasis in research lies in the application of sunscreens which either avoid the penetration of damaging sun rays into the skin or have a supportive effect on the endogenous pool of antioxidants. First results show a close correlation between the ICL-S measured on the one hand and various sun protection factors (SPF) as well as the UV doses applied on the other.

In addition to the direct in-vivo measurement in the skin of test subjects and the fast and simple test arrangement, a further major point is that the UV dosis applied for the SPF measurement is far below the minimal erytheme barrier.

This project (AiF-FV 11881 N) is sponsored by the Arbeitsgemeinschaft industrieller Forschungsvereinigungen "Otto von Guericke e.V.", a leading research association for the cosmetic industries in Germany.

Author

Dr. rer. nat. Stefan Benard



Dr. Stefan Benard studied Biology and Technical Biology and Bionics. 1996-1999: scientific assistant at the Institut für Medizinische Physik und Biophysik at the University of Leipzig. Since Mai 1999 he has been scientific assistant at the Institut Dr. Schrader Creachem. His activities includes the development and realization of research projects in the field of photo biophysics. In November 1999, the first forum of the leading research association for the cosmetic industry, FKI, took place at the Institute Dr. Schrader in Holzminden, Germany. The Institute Dr. Schrader Creachem is the research location of the FKI. Dr. Stefan Benard reported on his current project of the association.