For treatment,
cells were maintained in culture media without FBS overnight. The
cells were pretreated with EO and ascorbic acid for 24 h, washed
with phosphate buffer saline (PBS; Sigma, St. Louis, MO, USA) and
irradiated under UVB radiation. After UVB irradiation, cells were
again rinsed twice with PBS and immediately, incubated in fresh
culture media without serum, in the presence of EO and ascorbic
acid materials for further 24 h. All UVB irradiations were performed
under a thin layer of PBS.