Abstract:

Considering the growing evidence that microbial fermentation, as an optimum processing method, can improve the biological activity of herbal extracts in food and cosmetic additives fields. In recent years, owing to the unique aroma and pharmacological activity, lotus petals extract has been utilized in the preparation of cosmetic and food. However, none is available on the improvement of anti-melanogenic activity in the microorganism-fermented lotus petals extract （LPE）. Thus, in this study, it is hoped to enhance anti-melanogenic properties of lotus petals extract by using fermentation technology and clarify its mechanism of action. We screened five probiotics （L.plantarum CGMCC 1.124, L.fermentum DSMZ 20052, Bacillus subtilis CGMCC 1.943, B.natto CGMCC NO. 19463 and B.natto CGMCC NO. 19462） to ferment LPE with evaluating for their anti-melanogenic activity by mushroom tyrosinase and melanin formation inhibition assays, hoping to establish a new method to improve the anti-melanogenic activity of LPE. The results indicate that LPE fermented with L.plantarum CGMCC 1.124 （FLPE）, shows enhancement on anti-mushroom tyrosinase and anti-melanogenic activity in A-MSH-stimulated B16F10 melanocytes. In particular, compared with A-MSH incubation alone, co-incubation with 50 μg/mL FLPE reduces the melanin production to 86%±4.6%. To determine the main effectors of the anti-melanogenesis of FLPE, primary flavonoids from LPE and FLPE were isolated and determined by high performance liquid chromatography （HPLC）, nuclear magnetic resonance （¹H NMR, ¹³C NMR） and liquid chromatography mass spectrometry （LC-MS） analyses. The results of structure analysis and bioactivity evaluation show that flavonoid glycosides kaempferol-3-O-β-D-glucopyranoside （49.8%, 94.22 mg/g） and quercetin-3-O-β-D-glucuronide （13.6%） are bio-transformed to two bioactive aglycones, quercetin （14.4%, 26.43 mg/g） and kaempferol （60.9%, 70.76 mg/g）. Among these monomers, quercetin and kaempferol decrease the mushroom tyrosinase activity, but only quercetin shows anti-melanogenic activity by suppressing tyrosinase activity in B16F10 cells, regulating the mRNA expressions of melanogenesis-related enzymes （TYR, TRP-1 and TRP-2） and microphthalmia-associated transcription factor （MITF） and reducing the protein contents of TYR, TRP-1 and MITF in a dose-dependent manner. These data suggest that FLPE has a potential for skin whitening with quercetin as a functional compound. These results maybe contribute to developing healthy food and cosmetic, and expand the range of application of lotus petals.

Key words: lotus petals, fermentation, anti-melanogenesis, Lactobacillus plantarum, quercetin