Effects of ethanol extract of glossy privet fruit and its monomer tyrosol on the adhesion and migration of human epidermal melanocytes

Abstract

Objective To study the regulatory effect of ethanol extract of glossy privet fruit and its monomer tyrosol on the adhesion and migration of human epidermal melanocytes.Methods Epidermal melanocytes were isolated from human foreskin,and subjected to a primary culture.Mter 3-5 passages,the melanocytes were treated with various concentrations of ethanol extract of glossy privet fruit (0.0375-0.6 mg/ml)and tyrosol (0.125-2 mmol/L) for 24-72 hours.The XTT colorimetric assay was carried out to evaluate the proliferation of melanocytes,fibronectin (FN)-coated culture plates were used to evaluate the adhesion activity of melanocytes,and Transwell assay was conducted to assess the migration activity of melanocytes.Confocal laser microscopy was utilized to observe the structure and distribution of actin cytoskeleton in melanocytes,and cellular fluorescence intensity was determined by a semi-quantitative analysis.Statistical analysis was carried out by using unpaired t test.Results The adhesion activity of melanocytes to FN was significantly enhanced by the ethanol extract of 0.0375-0.6 mg/ml from glossy privet fruit (P ＜ 0.05 or 0.01),and by tyrosol of 0.5-2 mmol/L (P ＜ 0.05 or 0.01).As XTT assay showed,neither the ethanol extract of 0.15 mg/ml nor tyrosol of 2 mmol/L had cytotoxicity or promotive effect on cell proliferation.Hence,0.15 mg/ml and 2 mmol/L were determined as the working concentrations of ethanol extract and tyrosol respectively.The number of cells migrating through micropore membranes per high-power field (× 200) was 43.7 and 51.0 in melanocytes treated with the ethanol extract of 0.15 mg/ml and tyrosol of 2 mmol/L,respectively,significantly higher than that in untreated melanocytes (20.3,both P ＜ 0.01).Compared with untreated melanocytes,those treated with the ethanol extract of 0.15 mg/ml and those with tyrosol of 2 mmol/L showed higher intracellular fluorescence intensity (P ＜ 0.01) and more stress fiber bundles which congregated inside the cell membrane and around the nuclei.Conclusions The ethanol extract of glossy privet fruit and its monomer tyrosol can promote the adhesion and migration of human melanocytes in vitro,likely by promoting the congregation of actin cytoskeleton in melanocytes. Key words: Fructus ligustri lucidi; Melanocytes; Cell adhesion; Cell movement; Actins