Carteolol hydrochloride protects human corneal epithelial cells from UVB-induced damage in vitro

Purpose: To investigate whether carteolol hydrochloride has protective effects against ultraviolet B (UVB)-induced damage in human corneal epithelial cells (HCECs).

Methods: Cultured HCECs were exposed to a single dose of UVB 300 mJ/cm, and the cell viability was measured 12 hours after the UVB irradiation using a cell-counting kit. Test samples at 0.01-1.0 mmol/L (carteolol hydrochloride, timolol maleate, betaxolol hydrochloride, levobunolol hydrochloride, or nipradilol) were added to the HCECs before, during, or after UVB irradiation. UV absorption spectra for each drug sample were determined using a spectrophotometer. Hydrogen peroxide (H2O2) and carteolol hydrochloride were simultaneously added to the HCECs for 10 minutes, and the cell viability was measured 12 hours later. The ability of carteolol hydrochloride to scavenge superoxide anion (O2) and singlet oxygen (O2) was investigated using the MCLA chemiluminescence method.

Results: UVB irradiation decreased the number of viable HCECs in a dose-dependent manner. Carteolol hydrochloride at 1 mmol/L attenuated the UVB-induced cell damage when added before, during, or after UVB irradiation (P<0.01). Levobunolol hydrochloride at 1 mmol/L (P<0.01) added during or after irradiation and timolol maleate at 0.1 mmol/L or higher (P<0.05) added during irradiation attenuated the UVB-induced cell damage. Betaxolol hydrochloride and nipradilol had no effect. The UV absorption spectra of timolol maleate and levobunolol hydrochloride overlapped with the UVB wavelength spectrum, while carteolol hydrochloride, betaxolol hydrochloride, and nipradilol showed a partial overlap. Carteolol hydrochloride at 1 mmol/L (P<0.05) significantly inhibited H2O2-induced cell damage and was able to scavenge O2 (EC50 value: 48 mmol/L).

Conclusions: These data strongly suggest that carteolol hydrochloride has a protective action against UVB-induced HCEC damage, and its radical scavenging ability may be an important basis for this effect.