Submerged fermentation with Lactobacillus brevis significantly improved the physiological activities of Citrus aurantium flower extract

The physiological activity of the 50% ethanolic extract of Citrus aurantium flower before and after fermentation was investigated in this study. C. aurantium flowers grown in Taiwan were extracted using 100% methanol or 50% ethanol and then fermented by one of six microbes: four species of lactic acid bacteria (Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus brevis) anaerobically cultivated in MRS broth and two species of mold (Aspergillus oryzae and Aspergillus niger) aerobically cultivated in potato dextrose broth. The 50% ethanolic extract of C. aurantium flowers exhibited higher tyrosinase inhibition (IC50: 200.8 ± 11.6 mg/L) and antioxidative activity than did a 100% methanolic extract (IC50: 274.1 ± 15.7 mg/L). The 50% ethanolic extract fermented by L. brevis (L. brevis–fermented extract) exhibited the highest yield (86.2% ± 1.2%) and physiological activity. The L. brevis–fermented extract exhibited over 5.2-, 13.5-, 12.5-, 3.17-, and 4.29-fold higher antityrosinase activity, antioxidative activity, antibacterial activity, total flavonoid content, and antiwrinkle activity than did the unfermented extract. The L. brevis–fermented extract can be considered safe because it exerted no toxic effect on CCD-966SK or HEMn cells at concentrations of 400 and 200 mg/L, respectively. The fermented extract (40 mg/L) inhibited melanin formation, reducing it to 50.8% ± 2.3%. Furthermore, the L. brevis–fermented extract exhibited excellent antiaging and antiwrinkle activity, as determined from MMP-1, MMP-2, elastase, and collagenase activity. The improvement in physiological characteristics, especially the considerable formation of neohesperidin, is mainly attributable to biosynthesis or biotransformation by L. brevis during fermentation. In conclusion, the 50% ethanolic extract of C. aurantium flowers fermented with L. brevis can be used in cosmetics applications aiming for skin-whitening or antiwrinkle properties.