Assessment of eyebright (euphrasia officinalis L.) extract activity in relation to human corneal cells using in vitro tests.

BACKGROUND Euphrasia officinalis L. is an herb traditionally used in folk medicine, mainly in the treatment of eye disorders. AIMS The present study analyzed the activity of three extracts of E. officinalis L. (ethanol, ethyl acetate and heptane) on cultured human corneal epithelial cells (10.014 pRSV-T). STUDY DESIGN In vitro study. METHODS Toxicity, free radical scavenging activity and the immunomodulatory effects of the extracts were tested using the thiazolyl blue tetrazolium bromide (MTT) or Neutral Red, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ELISA tests, respectively. Moreover, nitric oxide levels and cytoskeleton architecture were analyzed after corneal cell incubation with the plant extracts. RESULTS We show that the biological effect depended on both the concentration and the extraction solvent used. Heptane extracts, distinct from those in ethanol and ethyl acetate, were toxic to 10.014 pRSV-T cells at low concentrations (25 μg/mL) and did not demonstrate free radical scavenging effects. All tested extracts decreased pro-inflammatory cytokine expression (IL-1β, IL-6 and TNF-α) and also anti-inflammatory IL-10 expression by human corneal cells when the extracts were added to the cell culture medium for 24 h. CONCLUSION In conclusion, we show that the promising effects of the application of E. officinalis L. preparations as a supplementary therapy for eye disorders are associated with the ethanol and ethyl acetate extracts, not the heptane extract.