Photo-protective and anti-melanogenic effect from phenolic compound of olive leaf (Olea europaea L. var. Kalamata) extracts on the immortalized human keratinocytes and B16F1 melanoma cells

Ethylacetate and butanol fractions of leaf extracts (OLE) showed the higher contents of total phenolic compounds than hexane and water fractions. Oleuropein contents were 4.21±0.57, 3.92±0.43, 0.32±0.03, 5.76±0.32, and 32.47±0.25 mg/ 100 g for ethanol extract, and hexane, chloroform, ethyl acetate, and butanol fraction, respectively. Treatment of ultraviolet-B (UVB) irradiated cells with 3 OLEs prepared by using ethylacetate and butanol at concentrations 0.001, 0.005, and 0.01% respectively showed significant recovery of cell viabilities. Treatment of dexametason 1 mM reduced tumor necrotic factor (TNF)-α secretion by about 40%. UVB irradiated immortalized human keratinocytes (HaCaT) cells were treated with 3 different OLEs at the same concentrations. Ethylacetate fraction showed the strongest inhibition activity with respect of reduction of the elevated TNF-α. Cytotoxicity of OLEs on the B16-F1 cells was evaluated through thiazolyl blue tetrazolium bromide (MTT) assay. Ethylacetate fraction has no cytotoxicity in the range of 0.005-0.01%. A slight cytotoxicity wasobserved at the concentration of 0.1% butanol fraction of OLE that caused 10% decrease in cell viability.