Abstract

DO.05.10

Influence of humic acids and related compounds on UV-B effects in lens epithelial cells

Wegener A.¹, Klöcking H.-P.², Klöcking R.², John S.^1
1Augenklinik der Rheinischen Friedrich-Wilhelms Universität, Bonn; ²Institut für Pharmakologie und Toxikologie, Friedrich-Schiller Universität Jena, Erfurt

Objective: Changes in the ozone concentration of the atmosphere caused an increased UV-B irradiation of the terrestrial surface leading to dermal and ocular tissue damage. Up to now, appropriate sun glasses provided ocular protection, but there has been little effort in developing chemical compounds for UV protection. This paper presents data investigating the UV-protective effect of 2 humic acids and a comparative compound in lens epithelial cell culture.
Methods: Human lens epithelial cell cultures from a spontaneously transformed cell line were cultivated under standard conditions to determine cytotoxicity of 1 natural and 1 synthetic humic acid and a reference compounds (para-aminobenzoic acid, PABA) in various concentrations. Cytotoxicity as well as UV-protective effects were studied microscopically, with the neutral red test and with Mitotracker^®. Radiation of the cell cultures was performed with a Waldmann dermal irradiation device (lmax = 315 nm; 2,96mJ/cm²; 5,92mJ/cm², 11,84mJ/cm²) in the absence of incubation medium.
Results: The reference compound PABA demonstrated a low cytotoxicity and a good UV-protective effect. The synthetic humic acid showed a much better relation between cytotoxicity and UV-protective effect than the natural compound. It was even better than PABA in long-term culture conditions. The 3 test procedures provide a detailed insight into UV-effects in human lens epithelial cells.
Conclusions: Synthetic humic acids could be useful for UV-protection of the ocular tissues, provided they are incorporated into appropriate ointments, like gel formulations.

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