Assessment of the cytoprotective effect of Vitex negundo ethanol extract on ultraviolet-C induced oxidative stress in human corneal epithelial cells

Human cornea is more susceptible to ultraviolet-C radiation during occupational injuries, and artificial sources such as welding arc, germicidal lamps, etc and continuous exposure leads to various ocular surface diseases. The cytoprotective role of plant extracts against oxidative damages induced by UVC irradiation is less studied in corneal epithelial cells.To investigate the protective of Vitex negundo ethanol (VNE) extract on ultraviolet-C (UVC) radiation induced oxidative stress in human corneal epithelial (HCE) cells. UVC radiation of wavelength (254 nm) and energy density 200 J/m2 was used to irradiate HCE, and cell viability was assessed by trypan blue assay. The reactive oxygen species (ROS) production was analyzed using 2’,7’-dichlorodihydrofluorescein diacetate (DCF-DA) method. Cell cycle analysis was done to check the effects of UVC irradiation and VN extract on the cell growth cycle of HCE cells. The mitochondrial membrane potential (Δψm) was checked by 5,5′,6,6'-tetrachloro-1,1',3,3′-tetrathylbenzimidazol carbocyanine iodide (JC-1) staining method. The HCE cell viability was diminished after UVC irradiation which was improved after VNE extract treatment. The morphological analysis revealed that UVC irradiated HCE cells lost membrane permeability which led to cell death thereby having decreased confluency. VNE extract effectively decreased UVC- induced ROS production and reduced the G1 phase arrest of the cell cycle analysis in HCE cells. The changes or loss in Δψm after UVC treatment was restored after VNE extract treated cells.VNE extract showed strong protective effect against UVC light induced injury in HCE cells which suggests the therapeutic use of these extracts in ocular surface injuries.