702 Rice ferment filtrate increases the production of hyaluronic acid, natural moisturizing factors, and ceramides by keratinocytes and improves the barrier function of the skin

Rice ferment filtrate is a fermented product of rice with microorganisms such as Aspergillus oryzae, yeasts, and Lactobacillus. Its beneficial effect for the skin conditions has been proposed for a long time. However, its precise role and the mechanism remain elusive. We demonstrated that daily topical treatment of a cosmetic ingredient of the rice ferment filtrate (Rice PowerTM No.11α lotion) improved the barrier function of the skin in a placebo-controlled study. After 4-week treatment to the inner forearm skin, the increase in the water content of stratum corneum was higher (10.1 vs 0.3μS, p<0.01), transepidermal water loss was lower (0.58 vs 1.34g/m2h, p<0.05), and water-holding capacity was 1.4-fold higher in the treated group than in the placebo group (N=15). The Ministry of Health, Labour and Welfare in Japan approved our product as the "Quasi-drug active ingredient." Next, we aimed to reveal the precise mechanism in vitro and in vivo. We found that the production of hyaluronic acid (HA) in 3D-cultured human epidermis treated with Rice PowerTM No.11α was 1.9-fold higher than in the control (p<0.001). In addition, the production of natural moisturizing factors (NMFs) was 1.2-fold higher in the treated group (p<0.05). It was not attributed to the amino acid ingredients of Rice PowerTM No.11α, but to the higher gene expression levels of FLG and BLMH. Furthermore, the ceramide synthesis gene expression levels were higher in the treated group. Moreover, in the placebo-controlled study of twice daily treatment of Rice PowerTM No.11α lotion to the inner forearm skin for 4 weeks, the ceramide production was 1.3-fold higher in the treated group than in the placebo group (p<0.05, N=13). Our results propose that Rice PowerTMNo.11α activates the production of HA, NMFs and ceramides by keratinocytes, and improves the barrier function of healthy skin.