Effects of Korean ginseng berry on skin antipigmentation and antiaging via FoxO3a activation

Abstract

Background: The ginseng berry has various bioactivities, including antidiabetic, anticancer, antiinflammatory, and antioxidative properties. Moreover, we have revealed that the active antiaging component of the ginseng berry, syringaresinol, has the ability to stimulate longevity via gene activation. Despite the many known beneficial effects of ginseng, its effects on skin aging are poorly understood. In this study, we investigated the effects of ginseng and the ginseng berry on one of the skin aging processes, melanogenesis, and age-related pigment lipofuscin accumulation, to elucidate the mechanism of action with respect to antiaging.

Methods: The human melanoma MNT1 cell line was treated with ginseng root extract, ginseng berry extract, or syringaresinol. Then, the cells were analyzed using a melanin assay, and the tyrosinase activity was estimated. The Caenorhabditis elegans wild type N2 strain was used for the life span assay to analyze the antiaging effects of the samples. A lipofuscin fluorescence assay was performed during 10 passages with the syringaresinol treatment.

Results: A 7-d treatment with ginseng berry extract reduced melanin accumulation and tyrosinase activity more than ginseng root extract. These results may be due to the active compound of the ginseng berry, syringaresinol. The antimelanogenic activity was strongly coordinated with the activation of the longevity gene foxo3a. Moreover, the ginseng berry extract had more potent antiaging effects, caused a life span extension, and reduced lipofuscin accumulation.

Conclusion: Taken together, our results suggest that these antimelanogenic effects and antiaging effects of ginseng berry mediate the activation of antioxidation-FoxO3a signaling.

Keywords: Caenorhabditis elegans; Ginseng berry; antiaging; lipofuscin; skin pigmentation.

Fig. 1

Ginseng root and ginseng berry extracts inhibit melanin accumulation by lowering tyrosinase activity. (A) MNT1 cells were treated with the ginseng root extract or the ginseng berry extract for 48 h, and the melanin levels were visualized after dissolving the cell pellets in 1N NaOH. (B) The melanin levels were quantified in the dissolved cell pellets by measuring the absorbance at 490 nm with a UV-vis spectrometer (Molecular Devices, Sunnyvale, CA, USA) and normalized to the protein input. (C) The tyrosinase activity was measured at 490 nm using a UV-vis spectrometer with melanin synthesized from L-dihydroxyphenylalanine (L-DOPA) by the tyrosinase present in the equal amounts of cell lysates (10 μg). Data are presented as mean ± standard deviation. * p < 0.05 by two–tailed Student t test.

Fig. 2

Ginseng berry extract reduces melanogenesis by inhibiting tyrosinase activity, and this effect is mainly derived from its effective component, syringaresinol. (A) The amount of syringaresinol in ginseng root or ginseng berry extract. The mean value (ug/mL) is presented. The melanin levels were visualized after dissolving the cell pellets in 1N NaOH (B) and quantified (C). The tyrosinase activity was also measured (D). Ginseng root, ginseng berry extract, or syringaresinol were used to treat MNT1 cells for 48 h. Data are presented as mean ± standard deviation. * p < 0.05 by two-tailed Student t test.

Fig. 3

Ginseng components have antioxidative activities. Ginseng root, ginseng berry, and syringaresinol have DPPH radical-scavenging activity (A) and H₂O₂ scavenging activity (B). Data are presented are the mean ± SD. * p < 0.05 by two-tailed Student t test.

Fig. 4

Ginseng root, ginseng berry, and syringaresinol induce the nuclear translocation of forkhead box-O3a (FoxO3a). (A) The indicated ginseng components were added to MNT1 cells for 48 h. The cells were stained with an antiFoxO3a antibody (FoxO3a; red) and 4′,6–diamidino–2–phenylindole (DAPI) (nucleus; blue). Representative images were obtained using a confocal laser scanning microscope (LSM7, Carl Zeiss, NY, USA) and merged. (B) Cells with FoxO3a localization were counted and depicted by the means of a confocal laser scanning microscope. Data are presented as mean ± standard deviation. Scale Bar = 100 μm. Ph, phase-contrast image.

Fig. 5

Ginseng components have potent antiaging activity. Ginseng root, ginseng berry, and syringaresinol induce a life span extension in the Caenorhabditis elegans wild type N2 strain. The survival curves (A) and the mean life span (B) are presented. The data were analyzed via a Kaplan–Meier survival analysis. The mean adult life span of each condition is (mean ± standard deviation) as follows: N2 control, 16.2 ± 3.0 d; GR 10 μg/mL, 17.4 ± 3.3 d; GR 50 μg/mL, 19.1 ± 4.5 d; GB 10 μg/ml, 19.0 ± 4.1 d; GB 50 μg/mL, 20.1 ± 4.0 d; SYR 250nM, 20.8 ± 3.9 d; and SYR 500nM, 22.4 ± 4.1 d. * p < 0.05 by Peto's log–rank test. The data represent one experiment with two additional repeats. (C, D) Ginseng components decrease lipofuscin accumulation in passaged human dermal fibroblasts. Dermal fibroblasts from a 28-yr-old female and a 56-yr-old male were treated with 100–500nM of syringaresinol for 10 passages, and the accumulated age-related lipofuscin was measured (C) and visualized (D). The accumulated lipofuscin levels were detected using a confocal laser scanning microscope (Ex: 350 nm; Em: 420 nm). The fluorescence intensities of the cells were calculated densitometrically by measuring the average pixel intensity in each cell. The data are presented as the mean ± standard deviation of three independent experiments. * p < 0.05 by two-tailed Student t test. Em, Emission; Ex, Excitation; GB, ginseng berry extract; GR, ginseng root extract; SYR, syringaresinol.