Acerola (Malpighia emarginata DC.) Juice Intake Suppresses UVB-Induced Skin Pigmentation in SMP30/GNL Knockout Hairless Mice.

Acerola (Malpighia emarginata DC.) is a fruit that is known to contain high amounts of ascorbic acid (AA) and various phytochemicals. We have previously reported that AA deficiency leads to ultraviolet B (UVB)-induced skin pigmentation in senescence marker protein 30 (SMP30)/gluconolactonase (GNL) knockout (KO) hairless mice. The present study was undertaken to investigate the effects of acerola juice (AJ) intake on the skin of UVB-irradiated SMP30/GNL KO mice.Five-week old hairless mice were given drinking water containing physiologically sufficient AA (1.5 g/L) [AA (+)], no AA [AA (-)] or 1.67% acerola juice [AJ]. All mice were exposed to UVB irradiation for 6 weeks. UVB irradiation was performed three times per week. The dorsal skin color and stratum corneum water content were measured every weekly, and finally, the AA contents of the skin was determined. The skin AA and stratum corneum water content was similar between the AA (+) and AJ groups. The L* value of the AA (+) group was significantly decreased by UVB irradiation, whereas AJ intake suppressed the decrease in the L* value throughout the experiment. Moreover, in the AJ group, there was a significant decrease in the expression level of dopachrome tautomerase, an enzyme that is involved in melanin biosynthesis.These results indicate that AJ intake is effective in suppressing UVB-induced skin pigmentation by inhibiting melanogenesis-related genes

The effect of acerola juice intake on the stratum corneum water content.

<p>The stratum corneum water content was measured every week for 6 weeks as described in the Materials and Methods. The values are expressed as the means ± the SEMs of five animals. ANOVA analysis: F_{2, 12} = 4.6, <i>P</i> < 0.05 at 5 weeks and F_{2, 12} = 25.2, <i>P</i> < 0.001 at 6 weeks. The asterisks indicate significant differences (*<i>P</i> < 0.05, **<i>P</i> < 0.01) compared with the AA (-) group by Tukey’s HSD post hoc comparisons. AA, ascorbic acid; AJ, acerola juice.</p

Body weight change.

<p>Body weight change.</p

The effect of acerola juice intake on epidermal morphology and thickness.

<p>(A) High magnifications of the epidermis from the skins of the AA (-), AA (+) and AJ groups are shown. The white arrows indicate the skin pigment. (B) The epidermal thicknesses in the HE-stained sections were measured as the distance between the top of the basement membrane and the bottom of the stratum corneum in five fields randomly selected from each animal. The values are expressed as the means ± the SEMs of five animals. ANOVA analysis: F_{2, 12} = 20.6, <i>P</i> < 0.001. The asterisk indicates a significant difference (**<i>P</i> < 0.01) compared with the AA (-) group by Tukey’s HSD post hoc comparisons. AA, ascorbic acid; AJ, acerola juice; Der., dermis; Epi., epidermis. Bar = 10 μm.</p

AA and DHA contents.

<p>The AA content (yellow bar) was determined by HPLC coupled with ECD, as described in the Materials and Methods section. The total AA (total bar height) content was determined by the reduction of DHA with TCEP. The DHA content (red bar) was calculated by subtracting the AA content from the total AA content determined in a different chromatographic run. N.D. indicates not detected. The values are expressed as the means ± the SEMs of five animals. ANOVA analysis: F_{2, 12} = 104.3, <i>P</i> < 0.001 for the AA content and F_{2, 12} = 90.9, <i>P</i> < 0.001 for the DHA content. The error bars represent the SEMs for the DHA and AA. AA, ascorbic acid; AJ, acerola juice.</p

The effect of acerola juice intake on gene expression in the skin.

<p>(A) Melanogenesis-related enzyme genes <i>Tyr</i>, <i>Tyrp1</i> and <i>Dct</i>. (B) Cytokine genes <i>Tnf-a</i> and <i>Edn1</i>. (C) Cell cycle progression gene <i>Ccnd1</i>. Quantifications of the mRNA are illustrated relative to the <i>Rplp1</i> mRNA. The mRNA levels of the AA (+) group were designated as 1.0. The values are expressed as the means ± the SEMs of five animals. ANOVA analysis: F_{2, 12} = 1.1, <i>P</i> = 0.369 for the <i>Tyr</i> gene, F_{2, 12} = 1.1, <i>P</i> = 0.372 for the <i>Tyrp1</i> gene, F_{2, 12} = 4.1, <i>P</i> < <i>0</i>.<i>05</i> for the <i>Dct</i> gene, F_{2, 12} = 6.3, <i>P</i> < <i>0</i>.<i>05</i> for the <i>Tnf-a</i> gene, F_{2, 12} = 2.3, <i>P</i> = 0.147 for the <i>Edn1</i> gene, and F_{2, 12} = 4.7, <i>P</i> < <i>0</i>.<i>05</i> for the <i>Ccnd1</i> gene. The asterisks indicate significant differences (*<i>P</i> < 0.05) compared with the AA (-) group by ANOVA followed by Tukey HSD post hoc comparisons. The daggers indicate significant differences (^†<i>P</i> < 0.05) compared with the AA (+) group by ANOVA followed by Tukey’s HSD post hoc comparisons. AA, ascorbic acid; AJ, acerola juice.</p

Primer sets used for qPCR analysis.

<p>Primer sets used for qPCR analysis.</p

Total AA, AA, and DHA concentrations in acerola juice.

<p>Total AA, AA, and DHA concentrations in acerola juice.</p

The effects of acerola juice intake on L* value and back skin colors.

<p>(A) The time course of the L* value (a measure of skin lightness). (B) Representative photographs of UVB-irradiated areas at 6 weeks. The values are expressed as the means ± the SEMs of five animals. ANOVA analysis: F_{6, 28} = 17.4, <i>P</i> < 0.0001 for the AA (-) group, F_{6, 28} = 4.4, <i>P</i> < 0.01 for the AA (+) group, and F_{6, 28} = 1.1, <i>P</i> = 0.39 for the AJ group. Sharps indicate significant differences (^#<i>P</i> < 0.05, ^##<i>P</i> < 0.01) compared with the start date by Dunnett's test for post hoc comparisons. ANOVA analysis: F_{2, 12} = 4.1, <i>P</i> < 0.05 at 2 weeks, F_{2, 12} = 6.7, <i>P</i> < 0.01 at 3 weeks, F_{2, 12} = 3.8, <i>P</i> = 0.053 at 4 weeks, F_{2, 12} = 24.2, <i>P</i> < 0.0001 at 5 weeks, and F_{2, 12} = 10.5, <i>P</i> < 0.01 at 6 weeks. The asterisks indicate significant differences (*<i>P</i> < 0.05, **<i>P</i> < 0.01) compared with the AA (-) group by Tukey’s HSD post hoc comparisons. The double daggers indicate significant differences (^††<i>P</i> < 0.01) compared with the AA (+) group by Tukey’s HSD post hoc comparisons. AA, ascorbic acid; AJ, acerola juice.</p