Effect of the Fructus Ligustri Lucidi extract and its monomers quercetin and oleanolic acid on the adhesion and migration of melanocytes and intracellular actin.

The present study aimed to investigate the effects of the Fructus Ligustri Lucidi (FLL) extract and its monomers quercetin and oleanolic acid on the adhesion and migration of human epidermal melanocytes (MCs) and intracellular actin. The human epidermal MCs were cultured and identified. The cells were treated with different concentrations of FLL extract, quercetin and oleanolic acid. The adhesion and migration abilities of the cells were determined by the fibronectin-coated culture experiment and Transwell assay, respectively. The structure and distribution of intracellular actin were observed by confocal laser microscopy, with semi-quantitative analysis. Results showed that compared with the control group, 0.0375-0.3 mg/ml of the FLL extract and 40 µM quercetin significantly improved the adhesion rate of MCs (P<0.05). The numbers of MCs permeating the microporous membrane in the 0.15 mg/ml FLL extract and 12 µM oleanolic acid groups were 43.7 and 30.3, respectively, significantly higher compared to the control group (P<0.01). In the control group, the intracellular actin was less, and the stress fiber structure was not clear. In the 0.15 mg/ml FLL extract, 12 µM oleanolic acid and 40 µM quercetin groups, there were numerous bunched stress fibers, indicating the aggregation of filamentous fibrous actin. The mean optical densities of actin expression in the 0.15 mg/ml FLL extract, 12 µM oleanolic acid and 40 µM quercetin groups were significantly higher compared to the control group (P<0.05). The FLL extract has a significant stimulatory effect on the adhesion and migration of human epidermal MCs. The mechanism may be associated with the promotion of intracellular actin cytoskeleton aggregation.