Anti-photoaging effect of fermented rice bran extract on UV-induced normal skin fibroblasts

Rice bran contains various polyphenolic compounds with anti-oxidative activities, and it has long been known to inhibit melanogenesis. Cofermentation of rice bran with Lactobacillus rhamnosus and Saccharomyces cerevisiae significantly reduced the melanin synthesis of the resulting extract to B16F1 melanoma cells. However, anti-aging and anti-inflammatory effects of these fermented rice bran extracts (FRBEs) were not investigated. The objective of this work was to investigate the ability of FRBE to protect fibroblast cultures against ultraviolet B (UV-B)-induced damage in vitro. To study the effect of FRBE on collagen synthesis, human fibroblasts were treated with 0.1, 0.5, or 1% of FRBE or 25 μM of As-2p over 3 days. The morphological change of fibroblasts, secretion of IL-1α, and pro-MMP-1 levels were evaluated. The rate of cell growth was reduced upon exposure of fibroblasts to UV-B radiation (30 mJ/cm²) and did not recover after FRBE treatment. FRBE did not induce morphological changes and necrosis in a dose-dependent manner. Immunohistochemistry confirmed increased collagen synthesis in a dose-dependent manner after UV-irradiated fibroblasts were treated with FRBE. FRBE treatment reduced the UV-B-induced release of IL-1α to levels found in non-irradiated controls. In fibroblasts subjected only to UV-B irradiation, the level of pro-MMP-1 increased approximately fourfold compared to non-irradiated cells. However, treatment with FRBE decreased the level of pro-MMP-1 to a level similar to that of As-2p treated cells; this result was confirmed by western blot analysis. This work indicates that FRBE can increase the synthesis of type I collagen, decrease the expression of MMP-1, and inhibit the production of IL-1α in UV-B irradiated human fibroblasts.