Abstract: Objective To investigate the protective effect of aloin on inducible nitric oxide synthase (iNOS) and nuclear factor kappa B (NF-kB) synthesis of HaCat cells induced by ultraviolet B (UVB) irradiation. Methods The proliferation of HaCat cells was measured by MTT method. iNOS mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR). NO production was assessed by spectrophotometric method, and expression of NF-kB P65 was measured by immunofluorescent staining. Results After irradiation with 30 mJ/cm² of UVB, proliferation of HaCat cells was decreased, and NO generation and iNOS mRNA synthesis in HaCat cells were increased. UVB irradiation could also activate the expression of NF-kB P65 and promote its translocation into nucleus. NO generation and iNOS mRNA synthesis were markedly down-regulated in a dose-dependent manner by pre-treatment with different concentrations of aloin. The activation of NF-kB P65 was inhibited while the proliferation of HaCat cells was increased. All the difference reached statistical significance (P<0.01). Conclusions Our Results confirm that aloin treatment could inhibit NF-kB P65 activation, and down-regulate iNOS mRNA expression and NO generation induced by UVB irradiation. Aloin might play an important role in the treatment of skin inflammatory diseases, especially ultraviolet irradiation injury.

Key words: Ultraviolet rays, Cells, cultured, Nitric-oxide synthase, NF-kappa B, Aloin