COMPARISON OF THE UV-B PROTECTIVE EFFECT OF NATURAL PEAT HUMIC ACIDS AND PARA-AMINOBENZOIC ACID (PABA)

摘要

The UV-B protective effect of naturally occurring peat humic acids (HA) arid p-aminobenzoic acid (PABA), a well-known photoprotective agent, was investigated in human promonocytic U937 cells. Using Cytomorph~o-b microtest plates as cell cultivation and test devices, test substances were allowed to interact with the cells either directly or indirectly (as UV-filter). As a measure of cell viability XTT reduction was determined 24,48 and 72 h after irradiation. The results demonstrate a remarkable UV-B protective effect for HA and PABA, which is rather caused by UV-B absorption than by pharmacological effects. Due to the broad UV absorption spectrum of HA substances of the HA type may considered promising sunscreen agents for application in medicine and cosmetics.