Volume 11 (2013) Article 3

by R. Klöcking, Y. Felber, M. Guhr, G. Meyer, R. Schubert and J.I. Schoenherr

Published online: 24.04.2013

Summary

Humic acids (HA) are known for their antiviral and UV-B protecting effects, and are considered promising as ingredients for a UV-protective lipstick which is being developed to minimise or even prevent recurrences of UV- induced herpes. In this study, the UV/Vis spectra of three natural HA and three synthetic HA-like substances are analysed to determine the appropriateness of their UV-absorbing characteristics for the product under development. The contribution of a matrix component (castor oil) to the total UV absorption of the lipstick is also assessed. The results confirm the expected high UV-B absorption of the individual test substances, but reveal considerable differences in the UV-A wavelength range. Castor oil absorbs only UV-B radiation; and when mixed with HA it enhances total absorption in the UV-B range, but reduces it in the UV-A range. This is probably due to molecular interactions between castor oil and HA. Preliminary results from cultures of human U937 cells assayed for survival 24 hours after exposure to UV-B radiation show that both HA and castor oil exert a significant concentration-dependent UV-B protective filter effect similar to that of the UV-B absorbing reference substance p-aminobenzoic acid (PABA).

Citation

Klöcking, R., Felber, Y., Guhr, M., Meyer,G., Schubert, R. & Schoenherr, J.I. (2013): Development of an innovative peat lipstick based on the UV-B protective effect of humic substances. Mires and Peat 11: Art. 3. (Online: http://www.mires-and-peat.net/pages/volumes/map11/map1103.php)

Reviewers

IMCG and IPS acknowledge the work of the reviewers.