Clinical effect of Pediococcus acidilactici PMC48 on hyperpigmented skin

BACKGROUND: The excessive production and accumulation of melanin in the epidermal skin layer can result in skin hyperpigmentation and darkening. Current technologies for regulating melanin are based on inhibiting melanin biosynthesis. They have low effectiveness and safety issues. AIMS: This study aimed to evaluate the potential role of Pediococcus acidilactici PMC48 as a probiotic strain in medicines and cosmetics for skin treatment. MATERIALS AND METHODS: Meanwhile, our research team has reported that P. acidilactici PMC48 strain isolated from sesame leaf kimchi can directly decompose the already synthesized melanin. It can also inhibit melanin biosynthesis. In the present study, we investigated the skin-whitening effect of this strain by arranging an 8-week clinical trial with 22 participants. PMC48 was applied to each participant's artificially UV-induced tanned skin in the clinical trial. Its whitening effect was investigated based on visual evaluation, skin brightness, and melanin index. RESULTS: PMC48 showed a significant effect on the artificially induced pigmented skin. The color intensity of the tanned skin was decreased by 47.647%, and skin brightness was increased by 8.098% after the treatment period. PMC48 also significantly decreased the melanin index by 11.818%, indicating its tyrosinase inhibition capacity. Also, PMC48 improved skin moisture content level by 20.943%. Additionally, 16S rRNA-based amplicon sequencing analysis showed a distinct increase in Lactobacillaceae in the skin by up to 11.2% at the family level without affecting other skin microbiota. Furthermore, it showed no toxicity in in vitro or in vivo analyses. DISCUSSION: These results indicate that P. acidilactici PMC48 is a promising probiotic strain that can be used to develop medicines and cosmetic products to solve skin-related problems. CONCLUSIONS: These results demonstrate that P. acidilactici PMC48 can be a potential probiotic for the cosmetic industry against different skin disorders.